-
*TM 3-4240-346-20&PTM 09204A/09205A-20&P/2
UNIT MAINTENANCE MANUAL(INCLUDING REPAIR PARTS AND SPECIAL TOOLS
LIST)
FOR
CHEMICAL BIOLOGICAL MASK: FIELD M40A1
(4240-01-370-3821-SMALL)(4240-01-370-3822-MEDIUM)(4240-01-370-3823--LARGE)
CHEMICAL BIOLOGICAL MASK: COMBAT VEHICLE M42A2
(4240-01-413-4100-SMALL)(4240-01-413-4101-MEDIUM)(4240-01-413-4102--LARGE)
* This manual supersedes the M40A1 part of TM
3-4240-300-20&P / TM 09204A/09205A-20&P/2, 31 July96, and
the M42A2 part of TM 3-4240-343-20&P/TM
09204A/09205A-20&P/2, 31 July 96.
WARNING - This document contains export-controlled technical
data whose export is restricted by the Army ExportControl Act
(Title 22, U.S.S.S., Sec 2751 et seq.) or Executive order 12470.
Violation of these export laws is subject tosevere criminal
penalties.
DISTRIBUTION STATEMENT - Distribution authorized to U. S.
Government agencies and their contractors toprotect technical or
operational information This determination was made on 24 June
1987. Other requests for thisdocument will be referred to:
Technical Director, U.S. Army, Edgewood Research, Development &
Engineering Center,ATN: SCBRD-ENL-V, Aberdeen Proving Ground, MD
21010-5423.
DESTRUCTION NOTICE Destroy by any method that will prevent
disclosure of contents or reconstruction of thedocument.
HEADQUARTERS, DEPARTMENT OF THE ARMYAND, HEADQUARTERS, MARINE
CORPS
1 AUGUST 1998
PCN 182 092041 00
-
WARNINGS point out dangerous steps in the procedures in this
manual Your safety depends on following the instructionsincluded in
all WARNINGS. Several general WARNINGS are included below:
The mask will not be fully effective in confined spaces when the
oxygen content of the air is too low. The CB maskhas only been
tested and verified to protect against all known military
agents.
DO NOT touch your skin (or the soldier) with n-Amyl acetate
(banana oil). It could irritate the skin. Wear rubbergloves.
DO NOT smoke around n-Amyl acetate (banana oil), it is
flammable.
DO NOT test mask assembly with n-Amyl acetate (banana oil) in a
closed, poorly ventilated area. Test outdoors or ina well-aired
room, n-Amyl acetate may be toxic if inhaled in quantity.
DO NOT wear contact lenses (soft or hard) while wearing CB
Protective Masks. Inadequate oxygen supply to thecorneal surface,
exposure to dust, dirt, and smoke/gas may cause serious vision loss
or eye damage. Soldiersrequiring vision correction are provided
optical inserts for their protective masks.
HEALTH/ENVIRONMENTAL HAZARD
There are two Mask Filter Canisters, the C2 and the C2A1. The C2
canister contains Chromium VI and damaged orunusable canisters are
considered Hazardous Waste. (Chromium VI is a known carcinogen if
inhaled or swallowed.)
The C2A1 canister is chromium-free but must continue to be
disposed of in accordance with State and LocalEnvironmental
Laws.
DO NOT throw away damaged or unusable canisters as ordinary
trash.
DO turn in damaged or unusable canisters to your hazardous waste
management office or Defense Reutilization andMarketing Office
(DRMO).
FIRST AID
For first aid refers to FM 21-11.
SAFETY DATA SHEETS
http://www.apgea.army.mil/RDA/pmnbc/c2aldisp.html
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
TECHNICAL MANUAL
DEPARTMENT OF THE ARMYAND HEADQUARTERS, MARINE CORPS
Washington, D.C., 1 AUGUST 1998
UNIT MAINTENANCE MANUAL
(INCLUDING REPAIR PARTS AND SPECIAL TOOLS LIST)
FOR
CHEMICAL BIOLOGICAL MASK: FIELD M40A1
(4240-01-370-3821--SMALL)(4240-01-370-3822--MEDIUM)(4240-01-370-3823--LARGE)
CHEMICAL BIOLOGICAL MASK: COMBAT VEHICLE M42A2
(4240-01-413-4100--SMALL)(4240-01-413-4101--MEDIUM)(4240-01-413-4102--LARGE)
REPORTING ERRORS AND RECOMMENDING IMPROVEMENTS
You can help improve this manual. If you find any mistakes or if
you know of a way to improve the procedures, please let usknow.
Mail you letter, DA Form 2028 (Recommended Changes to Publications
and Blank Forms), or DA Form 2028-2located in the back of this
manual direct to: Technical Director, U.S. Army, Edgewood Research,
Development &Engineering Center, ATTN: SCBRD-ENL-V, Aberdeen
Proving Ground, MD 21010-5423.
Marine Corps Users - Submit NAVMC FORM 10772 directly to
Commander, Marine Corps Logistics Base (Code 850), 814Radford Blvd,
AIbany, GA 31704-5000. In addition, a copy of the NAVMC 10772 or
naval message should be sent toMARCORSYSCOM (Code CSLENBC), 2033
Barnett Ave., Suite 315, Quantico, VA 22134-5010.
In either case, a reply will be sent to you.
i
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
TABLE OF CONTENTS
HOW TO USE THIS MANUAL
..................................................................................................................
iii
CHAPTER 1
INTRODUCTION..................................................................................................................
1-1
SECTION I. GENERAL INFORMATION
..................................................................................................
1-1
SECTION II. EQUIPMENT DESCRIPTION AND DATA
............................................................................
1-2
SECTION III. PRINCIPLES OF OPERATION
...........................................................................................
1-12
CHAPTER 2 UNIT MAINTENANCE
INSTRUCTION.................................................................................
2-1
SECTION I. REPAIR PARTS, SPECIAL TOOLS, TMDE, AND SUPPORT
EQUIPMENT........................... 2-3
SECTION II. SERVICE UPON RECEIPT
..................................................................................................
2-3
SECTION III. EQUIPMENT/USER FITTING
INSTRUCTIONS...................................................................
2-19
SECTION IV. TROUBLESHOOTING
........................................................................................................
2-29
SECTION V. PREVENTIVE MAINTENANCE CHECKS AND
SERVICES.................................................. 2-39
SECTION VI. HOSE ASSEMBLY CONVERSION
.....................................................................................
2-45
SECTION VII. MAINTENANCE PROCEDURES
.......................................................................................
2-53
SECTION VIII. CLEANING AND
SANITIZING...........................................................................................
2-77
SECTION IX. PREPARATION FOR STORAGE OR SHIPMENT
..............................................................
2-95
APPENDIX A - REFERENCES
................................................................................................................
A-1
APPENDIX B - MAINTENANCE ALLOCATION CHART (MAC)
...............................................................
B-1
APPENDIX C - UNIT MAINTENANCE REPAIR PARTS AND SPECIAL TOOLSLIST
.........................................................................................................................
C-1
APPENDIX D - EXPENDABLE AND DURABLE ITEMS LIST
..................................................................
D-1
CROSS-REFERENCE INDEXES
.............................................................................................................
I-1
INDEX.......................................................................................................................................................
INDEX 1
ii
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
HOW TO USE THIS MANUAL
The safest, easiest, and best way to do maintenance on the
Chemical-Biological Mask, M40A1/M42A2 is to use this
manual.Learning to use this TM is as easy as reading through the
next few pages. Knowing what's in this manual and how to use itwill
save you time and work, and will help you avoid exposing yourself
to unnecessary hazards while you do your job.
ORGANIZATION
Page ii has a table of contents to provide easy access to the
manual. Pages are numbered consecutively within eachchapter; each
page number is prefixed with a chapter number or appendix letter.
For example, page 5 of Chapter 2 isnumbered 2-5 and page 3 of
appendix B is numbered B-3.
This manual is divided into two chapters, four appendixes, and
an alphabetical index. Chapter 2 has an index at thebeginning of
the chapter to provide easy access to its content. Each chapter is
divided into sections. Chapter 1 containsgeneral information
pertaining to location of forms, destruction of Army material, how
to store and ship the mask, proceduresfor reporting any improvement
recommendations you may have, as well as, corrosion prevention and
control. Chapter 2gives unit maintenance instructions and includes
four types of maintenance activities. These are: Service Upon
Receipt;Troubleshooting or location of faults by symptoms you can
detect; Preventive Maintenance Checks and Service (PMCS);and
Maintenance Procedures that are used to correct faults and replace
failed parts. Within the Troubleshooting andmaintenance portions of
this manual, you will find the material in functional group code
order like the Maintenance AllocationChart in Appendix B of this
TM. This allows the TM to be aligned with its applicable Repair
Parts and Special Tools List(RPSTL). For information on how to use
the RPSTL, refer to the introduction in Appendix C.
Each section in this manual is further divided into three parts.
The first addresses procedures which are the same regardlessof
which mask you are using. The second part addresses those tasks
which are peculiar to the M40A1 and the thirdaddresses those
peculiar to the M42A2. Therefore, depending on which mask you are
using, you must follow theinstructions in the general part and the
part which is peculiar to your mask.
For instance, if you have the M40A1 mask, you must do the Before
PMCS checks under COMMON and those checks listedunder M40A1
PECULIAR Those tasks listed under M42A2 PECULIAR are not
required.
Those tasks which are considered to be COMMON and apply to
either mask are illustrated using the M42A2.
However, the differences between the M40A1 and M42A2 do not
impact on the task, and, in many cases, you willnot be able to tell
from the illustration which mask is being illustrated.
HOW TO FIND PROCEDURES
If you're using the manual to perform Troubleshooting, go to
Section IV, and read TROUBLESHOOTING PROCEDURESand proceed
according to the instructions there. If you're going to do
Scheduled Maintenance, you can turn directly toPreventive
Maintenance Checks and Services (PMCS), Section V, and proceed
according to the instructions there.
If you are using the manual to perform repair or replacement of
a part that you already know is bad, you would start bylocating the
part to be replaced in the Alphabetical index located at the back
of this manual. Look in the Alphabetical Indexfor a key noun from
the mask system or part nomenclature. The Alphabetical Index lists
each task under one or moreheadings also giving the location for
the installation and removal of some part. For example, the
procedure for CLEANINGAND SANITIZING would be listed under "C" for
Cleaning.
Once you've located the correct procedure, read through it to
determine if you have everything you need to perform the job.Make
sure all the Equipment Conditions have been met. Familiarize
yourself with the potential hazards described by theWARNINGS and
CAUTIONS. You must familiarize yourself with the entire maintenance
procedure before beginning themaintenance task.
iii
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
HOW TO USE A MAINTENANCE PROCEDURE
The first page of a maintenance procedure lists everything you
will need to perform that procedure. The followingparagraphs
describe all the blocks of information you will find there.
TOOLS. Individual tools from your mechanic's tool kit will not
be listed under this heading. If any tools from this kit
arerequired, the tool kit itself will be listed as the first item.
Special tools, and tools from any other source will be listed with
areference to a specific item and appendix number. The referenced
appendix will provide you with the necessary informationto find or
make the tool.
SUPPLIES. If any expendable or consumable supplies are needed to
perform the task, they will be listed under this headingalong with
the quantity in parentheses and a reference to a figure item and
appendix in the back of the TM. The referencedappendix will give
you the detailed information necessary to requisition the supply if
you don't have it on hand. Replacementparts are not normally listed
under this heading. The inspection steps in the removal or
disassembly procedure will tell youwhich parts to replace.
Mandatory repair parts ( parts that are destroyed in disassembly or
not normally reused, such asgaskets and lock washers) are listed
under this heading by their nomenclature only. Refer to Repair
Parts and Special ToolsList (RPSTL), Appendix C for information you
need on repair parts.
iv (v blank)
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
CHEMICAL BIOLOGICAL MASKS
M40A1
M42A2
1-0
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
CHAPTER 1INTRODUCTION
SECTION I. GENERAL INFORMATION
1-1. SCOPE
a. Type of Manual. Unit maintenance.b. Model Numbers and
Equipment Name. Chemical-biological (CB ) mask: field M40AI, and CB
mask combat vehicle
M42A2.c. Purpose of Equipment. Protects the face, eyes, and
lungs from field concentrations of CB agents, toxins, and
radioactive fallout particles.
1-2. MAINTENANCE FORMS, RECORDS, AND REPORTS
a. Department of the Army forms and procedures used for
equipment maintenance will be those prescribed by DAPAM 738-750,
The Army Maintenance Management System (TAMMS), as contained in the
MaintenanceManagement update.
b. Marine Corps forms and procedures used for equipment
maintenance are prescribed in TM 4700-15/1_.
1-3. DESTRUCTION OF ARMY MATERIAL TO PREVENT ENEMY USE
Refer to TM 43-0002-31 for methods of destruction.
1-4. PREPARATION FOR STORAGE OR SHIPMENT
Refer to Chapter 2, Section IX, for preparation for storage or
shipment.
1-5. REPORTING EQUIPMENT IMPROVEMENT RECOMMENDATIONS (EIR)
a. If you have ideas on how the M40A 1 or the M42A2 masks can be
changed or maintained more effectively, let usknow. Send us an EIR.
You, the user, are the only one who can tell us what you don't like
about your equipment. Letus know why you don't like the design. Put
it on an SF 368 (Quality Deficiency Report). Mail it to us at
Director, USArmy Armament and Chemical Acquisition and Logistics
Activity, ATTN: AMSTA-AR-QAW-A (RI), Rock Island, IL61299-7630.
We'll send you a reply.
b. Marine Corps users shall submit a Standard Form 368 (SF368)
in accordance with MCO4855. 10 directly to:Commander, Marine Corps
Logistics Base (Code 856), 814 Radford Blvd., Albany, GA
31704-5000. We will sendyou a reply.
1-6. CORROSION PREVENTION AND CONTROL (CPC)
a. CPC of Army material is a continuing concern. It is important
that any corrosion problems with this item be reportedso that the
problem can be corrected and improvements can be made to prevent
the problem in future items.
b. While corrosion is typically associated with rusting of
metals, it can also include deterioration of other materials suchas
rubber and plastic. Unusual cracking, softening, swelling, or
breaking of these materials may be a corrosionproblem.
c. If a corrosion problem is identified, it can be reported
using a Quality Deficiency Report, SF 368. Use of key wordssuch as
"corrosion", "rust", "deterioration", or "cracking" will assure
that the information is identified as a CPCproblem.
d. The form should be submitted to Director, US Army Armament
and Chemical Acquisition and Logistics Activity,ATTN:
AMSTA-AR-QAW-A (RI), Rock Island, IL 61299-7630.
e. Marine Corps Units report CPC problems using SF 368 and
procedures prescribed in TM 4700-15/1_.
1-1
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
SECTION II. EQUIPMENT DESCRIPTION AND DATA1-7. EQUIPMENT
CHARACTERISTICS, CAPABILITIES, AND FEATURES.
COMMON
The lightweight, CB masks (M40A1 / M42A2 ) are easy to assemble
for transport and storage. The mask assembly is keptdry, when
required by climate and mission, by a waterproof bag and stored in
a carrier made of mildew-resistant, waterrepellent, coated
nylon.
The facepiece is made of silicone rubber with an inturned
sealing surface so it can provide protection to face, eyes,
andrespiratory tract from CB agents, toxins and radioactive
particles. The mask assembly is not intended for use in an
oxygendeficient environment. Nor is it intended to provide
protection against carbon monoxide or ammonia It forms a
comfortableseal on a soldier's face as it protects against adverse
elements. The mask assembly is equipped with both front and
sidevoicemitters for ease of communication and an outlet valve body
with a drinking system. To ensure a comfortable fit, themask
assembly is issued in three sizes: small, medium and large which
are marked with S, M and L on the forehead toshow sizing. It is
also equipped with clear and neutral gray outserts to protect the
eyelens from scratches, reduce sun glareand prevent fogging in cold
weather.
The masks have a second skin, universal second skin, or
universal second skin (USMC) which fits to the facepiece
andprotects the facepiece from liquid agents, and a quick doff hood
made of lightweight, butyl rubber-coated fabric, whichprovides
protection to the head and neck from liquid toxic chemical agents.
The second skin, universal second skin, oruniversal second skin
(USMC) is issued in two sizes: small and medium/large which are
marked S and M/L on the exteriorleft cheek.
M40A1 PECULIAR
The CB mask, M40A1, consists of a facepiece and filter
canister.
M42A2 PECULIAR
The CB mask, M42A2, consists of a facepiece, canister carrier
and hose assembly . The M42A2 masks has microphonecommunication
capability that can couple with on board communication systems,
through the Combat VehicleCommunications (CVC) helmet.
1-8. LOCATION AND DESCRIPTION OF MAJOR COMPONENTS
COMMON
a. FACE PIECE ASSEMBLY
FACEPIECE (1). The following components are molded/assembled
into the silicone rubber facepiece: buckle tabs,facepiece openings
for eyelens, nosecup, voicemitters, outlet valve, and filter
canister/hose connectors.
HEAD HARNESS (2). Constructed of elastic webbing sewn to a
rectangular head pad and buckled to facepiece.The ends of the head
harness straps have metal strap end clips to prevent fraying of the
elastic webbing. Ends ofthe head harness straps pass through
buckles at the two forehead, temple and cheek positions. Elastic
webbingconnects the two forehead straps and holds them in proper
alignment when the mask assembly is worn. Headharness straps
attached to buckles at the ends of the tabs permit adjustment to
obtain proper fit of the maskassembly.
1-2
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
NOSECUP ASSEMBLY (3). Made of soft rubber, fits over the
soldier's nose and mouth. Diverts exhaled air towardthe outlet
valve to reduce fogging of the eyelens.
NOSECUP VALVE SEATS (4). Each of two nosecup valve seats holds
silicone rubber NOSECUP VALVE DISK (5),which allows filtered air to
enter nosecup and prevent moist exhaled air from fogging the
eyelens in cold weather.
INTERNAL DRINK TUBE (6). Allows the soldier to drink while
wearing the mask assembly.
AIRFLOW DEFLECTOR (7), located inside the mask assembly, directs
inhaled air over eyelens to reduce fogging.The airflow deflector
also supports the inlet valve disk and the inlet valve body.
INLET VALVE BODY (8) and INLET VALVE DISK (9), fits into the
airflow deflector, allows filtered air to enter themask assembly
and prevent moist exhaled air from entering the filter
canister.
OUTLET VALVE COVER (10). Protects outlet valve disk and outlet
valve housing from damage.
RETAINER (11). Holds external drink tube quick disconnect
coupling.
OUTLET VALVE DISK (12) and OUTLET VALVE HOUSING (13). Located
behind outlet valve cover; releasesexhaled air and closes on
inhalation to prevent contaminated air from entering mask
assembly.
FRONT (14) AND SIDE VOICEMITTERS (15). Transmits the soldier's
voice outside the mask assembly.
EXTERNAL DRINK TUBE (16). The External Drink Tube is used to
connect the mask assembly to the M1 Canteencap for drinking. It
consists of a length of hose and a quick disconnect coupling half
(17) that fits into the externaldrink tube retainer.
DURABILITY ENHANCEMENT BAND (18). Band placed around outlet
valve housing to ensure seal is maintained.
1-3
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
1-8. LOCATION AND DESCRIPTION OF MAJOR COMPONENTS (CONT)
COMMON (CONT)
b. FILTER CANISTER (19) filters out CB agents and other
particles from contaminated air.
NOTEThe soldier may be issued either the one piece hood OR the
quick doff hood andsecond skin OR universal second skin and quick
doff hood or hooded over-garment OR the universal second skin
(USMC) and hooded overgarment. Theyare identical in function and
effectiveness. However, the one piece hood may notbe removed during
decon operations.
c. ONE PIECE HOOD (20). Provides protection to the head and neck
against liquid toxic chemical agents encounteredin field
operations. Made of lightweight butyl rubber-coated fabric. It is
attached to the mask assembly during useand stowed in mask
carrier.
1-4
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
d. QUICK DOFF HOOD.
QUICK DOFF HOOD (21). Is made of butyl rubber-coated fabric,
which protects area of neck and head that is notcovered by mask
assembly against CB agents, toxins, and radioactive fallout
particles.
ELASTIC AROUND OPENING (22). Attaches quick doff hood to the
second skin. It enables easy removal of thequick doff hood.
ELASTIC AROUND NECK (23). Draws quick doff hood close to the
neck to protect from CB agents.
UNDERARM STRAPS (24). Retain quick doff hood on the shoulders.
Plastic fasteners (25) are used to attach thestraps.
e. UNIVERSAL SECOND SKIN (26). Is made of butyl rubber and
covers the mask assembly. It provides additionalprotection against
liquid agents. (Rubber catches and ridges are no longer needed
because the universal secondskin is now larger.)
Interfaces with hooded overgarments.
Extends beyond the mask assembly.
Interfaces with QDH..
1-5
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
1-8. LOCATION AND DESCRIPTION OF MAJOR COMPONENTS--(CONT )
COMMON (CONT)
f. SECOND SKIN ( M40A 1/ M42A2).
SECOND SKIN (27). Is made of butyl rubber, and covers the mask
assembly. It provides additional protectionagainst liquid
agents.
RUBBER CATCHES (28). Used to retain the quick doff hood on the
mask assembly.
The RIDGE (29) is also used to retain the quick doff hood.
g. UNIVERSAL SECOND SKIN (USMC only) (30). Is made of butyl
rubber and covers the facepiece. It providesadditional protection
against liquid agents. (Rubber catches and ridges are no longer
needed because the universalsecond skin is now larger.)
Interfaces with hooded overgarments.
Extends beyond the mask facepiece.
Interfaces with the QDH.
h. Outserts have RUBBER RINGS (31) that fit over mask assembly
eyelens rings to secure outserts to maskassembly. The CLEAR
OUTSERTS (32) and NEUTRAL GRAY OUTSERTS (33) prevent scratching of
eyelensfrom scratches and reduce fogging of eyelens in cold
weather. The neutral gray outserts are used to reduce sunglare.
1-6
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
i. M1 WATERPROOF BAG (34). The folded waterproof bag and a small
envelope containing the RUBBER BANDS(35) are packed in carrier. The
waterproof bag keeps the mask dry when required by climate and
mission.Instructions for use are printed on the waterproof bag.
j. FACEFORM(36)
Holds mask assembly in proper shape when stored longer than 30
days.
M40A1 PECULIAR
NOTEThe soldier may be issued either mask carrier. Major
differencesare size and accessory stowage locations.
k. Mask Carrier is made of mildew-resistant, water-repellant
fabric. It has adjustable straps. It is closed with a flap heldby
hook and pile material.
IMPROVED FIELD MASK CARRIER (37) is designed to serve the field
mask only. It has a larger velcro closingsurface, the AQD opening
has been eliminated, the ID area is now camouflaged, the stiffeners
have been removed,it is wider and not as deep, and the interior
pockets are larger.
FIELD MASK CARRIER (38) was designed to serve field and combat
vehicle masks.
1-7
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
1-8. LOCATION AND DESCRIPTION OF MAJOR COMPONENTS--(CONT )
M42A2 PECULIAR
I. DETACHABLE MICROPHONE (39). Located in the recess of the
front voicemitter.
j. CANISTER CARRIER Improved (40) - Original (41)
NOTEYou may have been issued the original canister carrier or
theproduct improved model of the canister carrier. They
areinterchangeable.
The IMPROVED CANISTER CARRIER (40) is larger and interfaces with
the a C2/C2A1 filter canisters, as well as, avariety of North
Atlantic Treaty Organization (NATO) filter canisters. The cover now
screws on rather than attachingwith lug bolts, there is now a slip
ring within the cover and the AQD is detachable and rotates.
The ORIGINAL CANISTER CARRIER (41) interfaces with the C2/C2AI
filter canisters only.
ARMOR QUICK DISCONNECT (42). Attached to the canister cover (43)
and permits the filter canister to be coupledto a vehicle's Gas
Particulate Filter Unit (GPFU).
1-8
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
c. HOSE ASSEMBLY (44). The hose assembly connects the filter
canister and canister carrier to the mask assembly.
M42A2 - The hose assembly is attached to the mask assembly with
the STAR KNOB (45). The hose assembly isremovable and can be
relocated on left or right side of the mask assembly.
NOTEThe soldier may be issued either mask carrier. Major
differencesare size and accessory stowage locations.
d. Mask Carrier is made of mildew-resistant, water-repellant
fabric. It has adjustable straps. It is closed with a flap heldby
hook and pile material.
COMBAT VEHICLE MASK CARRIER (46). This mask carrier has been
redesigned. It is now shaped to aid instowing the filter canister
and hose, the velcro closing area has been enlarged to prevent dirt
from entering themask carrier, the exterior pouch has been removed,
the ID area is now camouflaged, the stiffeners have beenremoved and
the interior pockets are larger. It was designed to serve the
combat vehicle mask only.
FIELD MASK CARRIER (47) was designed to serve field and combat
vehicle masks.
1-9
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
1-9 DIFFERENCE BETWEEN MODELS
This chart shows major equipment and differences between the
M40A1 and M42A2.
Table 1-1. Differences Between Models
MASK FEATURESCHEMICAL
BIOLOGICAL MASK
M40A1 M42A2
Facepiece
Filter canister is connected to end coupling of hose
assembly
Detachable star knob hose assembly
Filter Canister attached directly to facepiece
Hood (One-Piece)
Quick Doff Hood
Second Skin
Universal Second Skin
Universal Second Skin (USMC only)
Clear/Neutral Outserts
Detachable Microphone (External)
Front and Side Voicemitter
Field Mask Carrier
Improved Field Mask Carrier
Combat Vehicle Mask Carrier
Operation Capabilities:
Combat Vehicle
Transportable and stored in carrier
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
1-10
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
1-10EQUIPMENT DATA
a. Tabulated Data
Weight (with carrier and accessories):
M40A1 mask. 3.8 lbs. (1.73 kg)
M42A2 mask. 4.5 lbs. (2.05 kg)
Dimensions:
M40A1 mask Mask with carrier...12 x 14 x4.5 in. (30.5 x 35.6 x
11.4 cm.)
M42A2 mask Mask with carrier...12x 14 x4.5 in. (30.5 x 35.6 x
11.4 cm.)
b. Shipping and Storage Data.
Shipping and Storage Data is identical for the M40A1 and M42A2
masks.
Number and type of pack: 10 per fiberboard container, 1 per
fiberboard box.
Fiberboard container:
Dimensions: 34.375 x 22 x 16.75 in. (87 x 55.9 x 425 cm)
1-11
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
SECTION III. PRINCIPLES OF OPERATION
1-11PRINCIPLES OF OPERATION
a. M40A1 PRINCIPLES OF OPERATION
(1).Air enters the FILTER CANISTER (1), which is screwed into
the side of the mask. The filter canister filters out CBagents,
toxins, and radioactive fallout particles from contaminated air.
Air then passes over the AIRFLOWDEFLECTOR (2) which is located
inside the facepiece and on the same side as the filter canister.
The air thenmoves into the eye area of the facepiece.
(2).From the eye area, air enters the NOSECUP (3) through
NOSECUP VALVES (4). Filtered air from the nosecup isinhaled by the
soldier. Exhaled air is passed through the nosecup area and out
through the OUTLET VALVE (5).The OUTLET VALVE COVER (6) protects
the outlet valve from contamination and damage, and provides a
retainerfor the external drink tube.
1-12
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
b. M42A2 PRINCIPLES OF OPERATION
(1). Air enters the filter canister, which is held in the
CANISTER CARRIER (7). The filter canister filters out CB
agents,toxins, and radioactive fallout particles from contaminated
air. Air then passes through the HOSE (8) andDEFLECTOR (9) which is
located inside the mask assembly and on the same side as the hose
assembly. The airthen moves into the eye area of the mask
assembly.
(2). From the eye area, air enters the NOSECUP (10) through
NOSECUP VALVES (11). Filtered air from the nosecup isinhaled by the
soldier. Exhaled air is passed through the nosecup area and out
through the OUTLET VALVE (12).The OUTLET VALVE COVER (13) protects
the outlet valve from contamination and damage, and provides
aretainer for the external drink tube.
1-13 (1-14 blank)
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
CHAPTER 2 UNIT MAINTENANCE INSTRUCTIONS
Table of Contents
Para. Page
SECTION I. REPAIR PARTS, SPECIAL TOOLS, TMDE, AND SUPPORT
EQUIPMENT ...............2-3
2-1. COMMON TOOLS AND
EQUIPMENT...................................................................................................................2-3
2-2. SPECIAL TOOLS, TMDE, AND SUPPORT
EQUIPMENT......................................................................................2-3
2-3. REPAIR
PARTS.....................................................................................................................................................2-3
SECTION II. SERVICE UPON RECEIPT
..........................................................................................2-3
2-4.
GENERAL..............................................................................................................................................................2-3
2-5. SERVICE UPON RECEIPT OF
MATERIAL............................................................................................................2-3
2-6. IDENTIFYING AN INDIVIDUAL'S
MASK..............................................................................................................2-18
SECTION III. EQUIPMENT/USER FITTING
INSTRUCTIONS........................................................2-19
2-7. ADJUSTING MASK ASSEMBLY AT INITIAL
FITTING..........................................................................................2-19
2-8. CHECKING MASK ASSEMBLY FOR PROPER
FUNCTION.................................................................................2-23
2-9. CHECKING DRINKING SYSTEM FOR PROPER
FUNCTION..............................................................................2-28
SECTION IV.
TROUBLESHOOTING..............................................................................................2-29
2-10. TROUBLESHOOTING
PROCEDURES..............................................................................................................2-29
SECTION V. PREVENTIVE MAINTENANCE CHECKS AND SERVICES (PMCS)
.......................2-39
2-11. INTRODUCTION TO PMCS
TABLE...................................................................................................................2-39
2-12. PMCS
PROCEDURES.......................................................................................................................................2-39
SECTION VI. CONVERSION
PROCEDURES................................................................................2-45
2-13. LEFT/RIGHT FILTER CANISTER/HOSE ASSEMBLY
CONVERSION................................................................2-45
2-14. M40A1 TO M42A2
CONVERSION.....................................................................................................................2-51
2-15. M42A2 TO M40A1
CONVERSION.....................................................................................................................2-52
2-1
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
Table of ContentsPara Page
SECTION VII. MAINTENANCE PROCEDURES
............................................................................2-53
2-16.
GENERAL..........................................................................................................................................................2-53
COMMON TASKS
2-17. INTERNAL DRINK
TUBE...................................................................................................................................2-54
2-18. QUICK DISCONNECT COUPLING, EXTERNAL
DRINKTUBE...........................................................................2-56
2-19. HEAD
HARNESS...............................................................................................................................................2-57
2-20. NOSECUP VALVE
DISKS..................................................................................................................................
2-58
2-21. AIRFLOW DEFLECTOR, INLET VALVE, AND VALVE
BODY............................................................................2-59
2-22. OUTLET VALVE COVER AND OUTLET VALVE
DISK.......................................................................................2-63
2-23. SIDE VOICEMITTER, VOICEMITTER RETAINER, AND
GASKET.....................................................................2-65
2-24. INTERNAL DRINKTUBE
NIPPLE.......................................................................................................................2-66
2-25. OPTICAL INSERT
KIT.......................................................................................................................................2-68
M40A1 PECULIAR TASKS
2-26. M40A1
FACEPIECE...........................................................................................................................................2-73
M42A2 PECULIAR TASKS
2-27. M42A2
FACEPIECE...........................................................................................................................................2-74
2-28. CLAMP
COVER.................................................................................................................................................2-75
2-29. PORT
GASKET..................................................................................................................................................2-76
SECTION VIII. CLEANING AND
SANITIZING...............................................................................2-77
2-30. CLEANING
M40A1.............................................................................................................................................2-77
2-31. SANITIZING
M40A.............................................................................................................................................2-81
2-32. CLEANING
M42A2.............................................................................................................................................2-85
2-33. SANITIZING
M42A2...........................................................................................................................................2-91
SECTION IX. PREPARATION FOR STORAGE OR SHIPMENT
...................................................2-95
2-34. PREPARATION FOR STORAGE OR
SHIPMENT..............................................................................................2-95
2-2
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
CHAPTER 2UNIT MAINTENANCE INSTRUCTIONS
SECTION I. REPAIR PARTS, SPECIAL TOOLS, TMDE, AND
SUPPORTEQUIPMENT
2-1. COMMON TOOLS AND EQUIPMENT
For authorized common tools and equipment, refer to the Modified
Table of Organization and Equipment(MTOE) applicable to your
unit.
2-2. SPECIAL TOOLS, TMDE, AND SUPPORT EQUIPMENT
Special tools, TMDE, and support equipment required are listed
in Appendix C-Repair Parts and Special ToolsList (RPSTL) and
Appendix B-Maintenance Allocation Chart (MAC).
2-3. REPAIR PARTS
Repair parts are listed and illustrated in Appendix C of this
manual.
SECTION II. SERVICE UPON RECEIPT
2-4. GENERAL
This section contains instructions and procedures for services
to be performed upon receipt of a new mask.These services include
unpacking and checking the mask.
2-5. SERVICE UPON RECEIPT OF MATERIAL
a. Table 2-1 contains instructions for performing the services
required upon receipt of the M40A 1 mask.b. Table 2-2 contains
instructions for performing the services required upon receipt of
the M42A2 mask.
2-3
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-5 SERVICE UPON RECEIPT OF MATERIAL
Table 2-1. Service upon receipt -- M40A1 Mask
LOCATION ITEM ACTION REMARKS
UNPACKING
1. OUTER BOX,FIBERBOARD OFWOOD, ASAPPLICABLE
2. INNERFIBER-BOARDBOX
Flaps (fiberboard box) ortop (wood box)
a. Facepiece/second skinassembly.
WARNINGAfter removing the top of a woodbox, remove nails or bend
nails toprevent injury.
NOTEIf possible, retain shipping boxesfor possible future
turn-ins.
Open box by cutting tape andbanding on fiberboard boxes orremove
top by cutting bandingand prying open top of woodboxes. Remove
nails or bendnails over to prevent injury.Remove inner fiberboard
boxes.Remove barrier bar aroundfacepiece folder.
NOTESecond skin is packaged on top ofthe facepiece in the
facepiece/second skin or universal secondskin assembly.
Open inner box (1). Remove thefacepiece/universal second skinor
second skin assembly (2). Takethe facepiece/universal secondskin or
second skin assembly outof the sealed bag and discard thebag.
Remove universal secondskin (3) or second skin (4).
NOTEMasks stored more than 30 daysshall be stored with faceform
infacepiece. Keep all faceforms. DoNot Discard.
Loosen head harness straps offacepiece (5) and removeclamshell
(6) and faceform (7).Cut tabs (8) where indicated.Store at
organization level.Discard clamshell.
2-4
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
Table 2-1. Service upon receipt -- M40A1 Mask
LOCATION ITEM ACTION REMARKS
UNPACKING (CONT)
2.INNER FIBER-BOARD BOX (CONT)
b. Fiberboard separator:hood assembly, filtercanister,
outserts.
Remove protective polycovering(9) from eyelenses (10) by
pullingcovering away from eyelens tostretch, then forward to
remove.Discard protective covering.
Remove fiberboard separator(11).
Take quick doff hood (12) out ofheat-sealed bag and discard
bag.
Store unopened canisters (13)until issued. Record lot number
ofcanister in accordance with unitSOP.
Take clear (14) and neutral gray(15) outserts out of
heat-sealedbags and discard bags.
2-5
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-5 SERVICE UPON RECEIPT OF MATERIAL (CONT)
Table 2-1. Service upon receipt -- M40A1 Mask
LOCATION ITEM ACTION REMARKS
UNPACKING (CONT
INSPECTION
c. Poly-bag Mask Carrier
d. Waterproof bag
e. Heat sealed bag-manual
Take improved field mask carrier(16) out of bag and discard
bag.Take field mask carrier (17) out ofbag and discard bag.
Remove waterproof bag (18) inself-sealing plastic bag. Checkthat
three rubber bands (19) areincluded.
Take manual (20) out of heat-sealed bag. Bag may be retainedto
protect manual.
Inspect equipment for damageincurred during shipment.
Ifequipment has been damaged,report the damage on SF 364,Report of
Discrepancy (ROD).Check equipment against packingslip to see if
shipment is complete.Report all discrepancies inaccordance with the
instructionsof DA PAM 738-750.
2-6
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
Table 2-1. Service upon receipt -- M40A1 Mask
LOCATION ITEM ACTION REMARKS
PREPARINGTO STOWTHE MASK CARRIER
a. Universal second skin orsecond skin
b. Clear outserts
c. Mask Assembly
d. Mask Assembly (22)(mask assembly, hood,head harness
andfaceform).
e. Mask Assembly (23)(mask assembly, headharness and faceform).
(Foruse with hoodedovergarments.) (USMConly)
Install universal second skin (3) orsecond skin (4) on facepiece
(seeOperator's Manual).
Install clear Outserts (15) onfacepiece (see
Operator'sManual).
Record alphanumeric number (21)in a property book or log IAW
unitSOP.
Place faceform (7) into maskassembly. Place neatly foldedquick
doff hood ( 12) into back offaceform. Tighten head harness tohold
quick doff hood.
Place faceform into maskassembly. Tighten head harnessto hold
facefom
2-7
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-5 SERVICE UPON RECEIPT OF MATERIAL (CONT)
Table 2-1. Service upon receipt -- M40A1 Mask
LOCATION ITEM ACTION REMARKS
STOWING IMPROVEDFIELDMASK CARRIER
a. Waterproof bag
b. Neutral gray outserts
c. Operator's manual
d. Mask Assembly
a. Install waterproof bag (18 )inside left end pocket.'
b. Install neutral gray outserts (14)in left back pocket.
c. Pack operator's manual (20) inthe right back pocket.
d. Store the mask assembly (22).
2-8
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
Table 2-1. Service upon receipt -- M40A1 Mask
LOCATION ITEM ACTION REMARKS
STOWINGFIELDMASKCARRIER
a. Waterproof bag
b. Neutral gray outserts
c. Operator's manual
d. Mask Assembly
a Install waterproof bag (18 )inside left back pocket.
b. Install neutral gray outserts (14)in back middle pocket.
c. Pack operator's manual (20) inthe right back pocket.
d. Store the mask assembly (22).
2-9
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-5. SERVICE UPON RECEIPT OF MATERIAL (CONT)
Table 2-2. Service upon receipt -- M42A2 Mask
LOCATION ITEM ACTION REMARKS
UNPACKING
1. OUTERBOX,FIBERBOARD ORWOOD, ASAPPLICABLE
2. INNER FIBER-BOARD BOX
Flaps (fiberboard box) ortop (wood box)
a. Facepiece fiberboardfolder, outserts, and secondskin or
universal secondskin.
WARNINGAfter removing the top of a woodbox, remove nails or bend
nails toprevent injury.
NOTEIf possible, retain some shippingboxes for possible future
turn-ins.Open box by cutting tape andbanding on fiberboard boxes
orremove top by cutting bandingand prying open top of woodboxes.
Remove nails or bendnails over to prevent injury.Remove inner
fiberboard boxes.Remove barrier bar aroundfacepiece folder.
NOTESecond skin, or universal secondskin is packaged on top of
thefacepiece in the facepiece holder.
Take clear (1) and neutral gray (2)outserts out of bags and
discardbags.
2-10
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P12
Table 2-2. Service upon receipt -- M42A2 Mask
LOCATION ITEM ACTION REMARKS
UNPACKING (CONT)
2. INNER FIBER-BOARDBOX (CONT)
a. Facepiece fiberboardfolder, outserts, and secondskin, or
universal secondskin. (Cont)
b. Facepiece and faceform.
c. Mask Carrier
NOTEMasks stored more than 30 daysshall be stored with faceform
inmask assembly. Keep allfaceforms. Do Not Discard.
Remove facepiece folder (3).Remove facepiece (4) anduniversal
second skin (5), orsecond skin (6) and discard bothfolder and
bag.
Loosen head harness straps offacepiece (7) and removeclamshell
(8) and faceform (9).Cut tabs (10) where indicated.Store faceform
at organizationlevel. Discard clamshell.
Remove protective poly-covering(11) from eyelenses (12)
bypulling covering away fromeyelens to stretch, then forward
toremove. Discard protectivecovering.
Take combat vehicle mask carrier(13) out of bag and discard
bag.
2-11
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-5. SERVICE UPON RECEIPT OF MATERIAL (CONT)
Table 2-2. Service upon receipt -- M42A2 Mask (Cont)
LOCATION ITEM ACTION REMARKS
UNPACKING (CONT) d. Mask Carrier.
e. Quick doff hood(M42AI/M42A2).
f. Detachable microphone(M42A2).
Take field mask carrier (14) out ofbag and discard bag.
Take quick doff hood (15) out ofbag and discard bag.
Take detachable microphone (16)out of bag and discard bag.
2-12
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
Table 2-2. Service upon receipt -- M42A2 Mask
LOCATION ITEM ACTION REMARKS
UNPACKING(CONT)
h. Canister Carrier
i. Vacuum sealed cancontaining filter canister.
j. Hose assembly
k. Waterproof bag
l. Heat sealed bag-manual
Take canister carrier (17) out ofbag and discard bag.
Store unopened can (18) until is-Sued. Record lot number of
filtercanister in accordance with unitSOP.
Take hose assembly (19) out ofbag and discard bag.
Remove waterproof bag (20) fromplastic bag and discard
plasticbag. Check that three rubberbands (21) are included.
Take manual (22) out of bag. Bagmay be retained to
protectmanual.
2-13
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/
2-5. SERVICE UPON RECEIPT OF MATERIAL (CONT)
Table 2-2. Service upon receipt -- M42A2 Mask (Cont)
LOCATION ITEM ACTION REMARKS
INSPECTION
PREPARING TO STOWTHE MASK CARRIER
a. Universal second skin orsecond skin
b. Clear outserts
c. Detachable Micro-phone (M42A2).
Inspect equipment for damageincurred during shipment.
Ifequipment has been damaged,report the damage on SF 364,Report of
Discrepancy (ROD).Check equipment against packingslip to see if
shipment is complete.Report all discrepancies inaccordance with the
instructionsof DA PAM 738-750.
Install universal second skin (5)(see Operator's Manual)
orsecond skin (6) (see Operator'sManual) on facepiece.
Install clear Outserts (1) onfacepiece (see
Operator'sManual).
Attach detachable microphone(16) to front voicemitter opening
offacepiece (see Operator'sManual).
2-14
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
Table 2-2. Service upon receipt -- M42A2 Mask
LOCATION ITEM ACTION REMARKS
PREPARING TO STOWTHE MASK CARRIER(CONT)
d. Mask assembly
e. Hose Assembly
f. Mask assembly (24)(mask assembly, hood,head harness and
face-form).
g. Mask assembly (25)(mask assembly, hood,head harness and
face-form). (For use with hoodedovergarments.)(USMC only)
Record 13 digit alphanumericnumber (23) in a property book orlog
IAW unit SOP.
Attach the hose assembly (19) tothe mask assembly (4)
(seeOperator's Manual).
Place faceform (9) into maskassembly. Place neatly foldedquick
doffhood (15) (M42A1/M42A2) into back of faceform.Tighten head
harness to holdquick doff hood.
Place faceform into maskassembly. Tighten head harnessto hold
faceform.
2-15
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-5. SERVICE UPON RECEIPT OF MATERIAL (CONT)
Table 2-2. Service upon receipt -- M42A2 Mask (Cont)
LOCATION ITEM ACTION REMARKS
STOWING THECOMBAT VEHICLEMASK CARRIER
a. Waterproof bag
b. Neutral gray outserts
c. Manual
d. Canister Carrier
e. Mask Assembly
Store waterproof bag (20) in rightpocket.
Store neutral gray outserts (2) inleft pocket.
Store operator's manual (22) inthe middle pocket.
Store the canister carrier (17).
Store the mask assembly (24).
2-16
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
Table 2-2. Service upon receipt -- M42A2 MaskLOCATION ITEM
ACTION REMARKS
STOWING THE FIELDMASK CARRIER
a. Waterproof bag
b. Neutral gray outserts
c. Manual
d. Canister Carrier
e. Mask Assembly
Store waterproof bag (20) ininside left end pocket.
Store neutral gray outserts (2) inleft back pocket.
Store operator's manual (22) inthe right back pocket.
Store the canister carrier (17).
Store the mask assembly (24).
2-17
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-6. IDENTIFYING AN INDIVIDUAL' S MASK
Although a mask will be used only by the soldier to whom it is
issued and fitted, do not make permanent identificationmarking on
either mask or mask carrier (AR 700-84). A card may be placed in
the exterior side pocket with the soldier'sname or a code number
for identification purposes. The date the mask was tested and
fitted to the soldier along with the IDcode will be recorded in
accordance with local SOP. Include the lot number of the canister
and the mask assembly.
Each unit will devise its own code to ensure operational
security. Take care not to include any designations that may
identifythe parent organization.
2-18
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
SECTION III. EQUIPMENT/USER FITTING INSTRUCTIONS
2-7. ADJUSTING MASK ASSEMBLY AT INITIAL FITTING
THIS TASK COVERS: a. Putting on mask assembly b. Adjusting mask
assembly c. Checking mask assembly for fit
INITIAL SETUP:
Personnel Required:NBC NCO or other trained personSoldier to be
fitted
Applicable Configurations:M40A1/M42A2
Materials/Parts:M41 Protection Assessment Test System (If
Available)ORn-Amyl acetate (banana oil) (item 11, app D)ORStannic
Chloride (tube smoke) (item 16, app D)
References:TC 3-41
WARNINGBefore putting on and adjusting mask assembly, soldiers
shallremove all hairpins, combs, hair knots, buns, or braids that
willinterfere with mask assembly seal. Soldiers must be cleanshaven
to prevent mask assembly leaks.
DO NOT wear contact lenses (soft or hard) while wearing
CBProtective Masks. Inadequate oxygen supply to the cornealsurface,
exposure to dust, dirt, and smoke/ gas may causeserious vision loss
or eye damage. Soldiers requiring visioncorrection are provided
optical inserts for their protective masks.
NOTEInitial mask assembly fitting should be performed by the
unit NBC NCO or other trained person.There is no special tool for
sizing with the M40A1/M42A2 masks. You will have to use
yourjudgement and the guidelines found in this paragraph on size
selection. Initial fitting is donewithout the hood installed.
The protective mask fit may be checked by the following
equipment/tests. The order of preferencefor mask fitting and
testing is the M41 Protection Assessment Test System (PATS) if
available, n-Amyl acetate (banana oil), or stannic chloride (tube
smoke).
Detailed instructions for checking the fit with the M41 PATS is
found in the M41 operator'smanual and in TC 3-41. Detailed
instructions for checking the fit with banana oil is in para 2-8
ofthis manual.
After initial fitting of soldier's mask, determine if soldier
fires from right or left. Convert maskaccordingly (para 2-13).
Determine if soldier requires vision correction and install as
required(para 2-25).
2-19
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-7. ADJUSTING MASK ASSEMBLY AT INITIAL FITTING (CONT)
a. PUTTING ON MASK ASSEMBLY
WARNINGEdges of open can are sharp.
1. Use attached key (1) to open canister can (2) and remove
filter canister (3).
NOTEOptical inserts should be installed, if required.
2. Install filter canister on mask assembly (4) (M40A1
only).
3. Feed hose end connector (5) through canister carrier (6)
(M42A2 only).
4. Install filter canister on hose connector and secure canister
carrier cover (7) (M42A2 only).
5. Loosen head harness (8) so that strap ends are approximately
1 in. (2.5 cm) from buckles.
6. Pull head harness over front of mask assembly (9).
7. Hold hair back from sealing area and place chin in the chin
pocket (10).
8. Have soldier slip head harness over head while holding mask
assembly against face.
2-20
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
b. ADJUSTING MASK ASSEMBLY
1. Have soldier hold mask assembly (9) tightly against chin.
2 (NBC NCO) Center head harness pad (11) on back of soldier's
head and have soldier hold in place.
3. (NBC NCO) Place finger or thumb under buckle (12) of forehead
strap (13). Then give strap end short, sharp tugsuntil buckle feels
snug. Adjust other forehead strap in same manner.
4. (NBC NCO) Place finger or thumb under buckle (14) of cheek
strap (15) and adjust cheek strap until it feels snug.Adjust other
cheek strap in same way.
5. Have soldier release mask assembly. Mask assembly should not
slip down. If mask assembly slips, readjustforehead straps and
cheek straps until mask assembly remains in place.
6. (NBC NCO) Place finger or thumb under buckle (16) of temple
strap (17) and adjust temple strap until buckle feelssnug against
finger. Repeat adjustment on other temple strap.
CAUTIONImproperly adjusted internal drink tube may irritate lips
if ittouches them while wearing mask assembly.
7. Ask if internal drink tube touches soldier's lips. Adjust
length of internal drink tube if necessary (para 2-17).
2-21
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-7. ADJUSTING MASK ASSEMBLY AT INITIAL FITTING (CONT)
c. CHECKING MASK ASSEMBLY FOR FIT
WARNINGSoldier's safety depends on proper fitting mask
assembly.
NOTEWhen doffing mask, only loosen the cheek straps.
1. Edge of mask assembly (9) comes up on forehead but not into
hairline and within 1 in. (2.5 cm) of ear.
2 Temple straps (17) and cheek straps (15) do not cut into
ears.
3. Soldier's pupils are within the center one-third area
(vertical) (18) of the eyelens (19). Adjust optical inserts
ifrequired (para 2-25).
4. Mask assembly does not press flesh so tightly that eyes are
partly closed.
5. Bottom of mask assembly does not cut into throat.
6. Skin in front of ear is not wrinkled.
7. Nosecup (20) does not obscure vision.
8 If mask assembly still does not meet above standards, try
another size mask.
NOTEFOLLOW-ON MAINTENANCE: Check the mask assembly for Proper
Function. (para 2-8).
2-22
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-8. CHECKING MASK ASSEMBLY FOR PROPER FUNCTION
THIS TASK COVERS: a. Testing mask assembly with M41 PATSb.
Testing mask assembly with n-Amyl acetate
INITIAL SETUP:
Applicable Configurations:M40A1/M42A2
Personnel Required:NBC NCO or other trained personSoldier to be
tested
Materials/Parts:M41 PATSApplicator (item 1, app D)n-Amyl acetate
(banana oil) (item 11, app D)Rubber gloves (item 8, app D)
References:
TM 3-4240-346- 10/TM09204A/09205A-10/1.TC 3-41Commercial Manual
(M41)
NOTEPMCS should be conducted and verified prior to proper
function testing.
The order of preference for mask fitting and testing is the M41
Protection Assessment Testsystem (PATS) if available, n-Amyl
acetate (banana oil), or stannic chloride (tube smoke).
COMMON
a. TESTING MASK ASSEMBLY WITH M41 PATS
1. Have soldier put on and adjust mask assembly (para 2-7).
2. Refer to TC 3-41 and Commercial Manual for instructions on
the use of the M41 PATS.
2-23
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-8. CHECKING MASK ASSEMBLY FOR PROPER FUNCTION (CONT)
COMMON (CONT)
b. TESTING MASK ASSEMBLY WITH N-AMYL ACETATE
WARNINGN-amyl acetate is flammable. DO NOT touch skin (or the
soldier)with n-Amyl acetate. It could irritate the skin. Wear
rubbergloves. DO NOT smoke around n-Amyl acetate. Keep
n-Amylacetate away from an open flame. DO test mask assembly in
awell-ventilated room. N-Amyl acetate may be toxic if inhaled
inquantity.
NOTESoldier should breathe deeply through nose only. If soldier
smells n-Amyl acetate just beforemasking, test results will be
inaccurate.
1. Dip applicator in n-Amyl acetate (banana oil).
2. Move applicator approximately 1 to 2 in. (2.5 or 5.1 cm) from
mask assembly as follows:
a. Have soldier turn head to left and move applicator completely
around outer edge of mask assembly.
b. Have soldier turn head to the right, again move applicator
around outer edge of mask assembly.
2-24
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
c. Have soldier tilt head upward and turn head from side to
side, move applicator under chin around outer edge ofmask
assembly.
d. Have soldier tilt head forward, move applicator around outer
edge of mask assembly.
2-25
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-8. CHECKING MASK ASSEMBLY FOR PROPER FUNCTION (CONT)b. TESTING
MASK ASSEMBLY WITH N-AMYL ACETATE (CONT)
M40A1 PECULIAR
e. Have soldier smile and frown while looking straight ahead.
Move applicator around both eyelenses (1), frontvoicemitter (2),
side voicemitter (3), filter canister (4) and outlet valve cover
(5).
f. Instruct soldier to press palms firmly over filter canister,
but not so firmly that mask assembly is distorted andloses its
seal. Have soldier breathe in, creating a vacuum and collapsing
mask assembly. Move applicatoraround outer edge of mask assembly
before having soldier breathe out.
M42A2 PECULIAR
g. Have soldier smile and frown while looking straight ahead.
Move applicator around both eyelenses (1), frontvoicemitter (2),
side voicemitter (3), star knob (6), and outlet valve cover
(5).
h. To test seal integrity for the connector at each end of the
hose assembly, check the clamp cover (7) on eachend of the hose
(8).
i. Move applicator around the canister carrier (9).
j. Instruct soldier to press palm firmly over Armor Quick
Disconnect Opening (10). Have soldier breathe in,creating a vacuum
and collapsing mask assembly. Move applicator around outer edge of
mask assembly beforehaving soldier breathe out.
2-26
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
NOTEIf soldier being tested smells n-Amyl acetate (banana oil)
during initial fitting and testing,a 5-7 minute odor sensitivity
recovery period is required before retesting.
4. If soldier can smell n-Amyl acetate, readjust head harness to
improve fit (para 2-7) and repeat above check.
5. If soldier cannot smell n-Amyl acetate, have him unmask and
smell the applicator to be sure that his sense of smellis not
impaired. If soldier's sense of smell is impaired, the mask
assembly must be tested in a CS (irritant) chamberor using a smoke
tube (item 16, app D) and an aspirator bulb (item 4, app D)
containing stannic chloride, whichproduces an irritating acid
smoke. The smoke tube test should be conducted in still air in an
area that can beventilated.
NOTEFOLLOW-ON MAINTENANCE: Remove mask assembly and stow in
carrier in accordancewith TM 3-4240-346-10/TM 09204A/09205A-10.
2-27
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-9. CHECKING DRINKING SYSTEM FOR PROPER FUNCTION
THIS TASK COVERS: Testing Drinking System
INITIAL SETUP:
Applicable Configurations:M40A1/M42A2
Personnel Required:NBC NCO or other trained personSoldier (mask
wearer)
TESTING DRINKING SYSTEM
a. Steady mask assembly (1), withdraw quick disconnect coupling
half (2) from retainer (3) and let it hang freely.
b. Grasp internal drink tube (4) between your lips.
WARNINGIf resistance is not felt when checking drinking system,
the drinking system leaks.
c. Blow into internal drink tube. If resistance is not felt,
drink system is leaking.
d. A more positive test may be done on the external drink tube
quick disconnect by the following procedure:(1) Fill cup (5) full
of water.(2) Place mask assembly on face.(3) Dip quick disconnect
in cup filled with water.(4) Blow into internal drink tube.(5)
Watch for bubbles in water. If no bubbles, quick disconnect is
operational. If bubbles are detected, the
quick disconnect is not operational. (Refer to para 2-18).
2-28
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
SECTION IV. TROUBLESHOOTING
2-10. TROUBLESHOOTING PROCEDURESa. Perform functional test
first. Then use the symptom index for quick access to the
troubleshooting procedures.b. The following describes the use of
the troubleshooting procedures.
SYMPTOM INDEX PAGE
COMMON
1. Eyelens Fog
Excessively.....................................................................................................................2-30
M140A1 PECULIAR
2. Insufficient Air to
User.........................................................................................................................2-31
3. Mask Assembly Fails To
Seal..............................................................................................................2-32
M42A2 PECULIAR
4. Insufficient Air to
User.........................................................................................................................2-35
5. Mask Assembly Fails To
Seal..............................................................................................................2-36
2-29
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-10. TROUBLESHOOTING PROCEDURES - (CONT)
COMMON
2-30
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
M40A1 PECULIAR
2-31
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-10. TROUBLESHOOTING PROCEDURES - (CONT)
M40A1 PECULIAR (CONT)
2-32
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-33
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/
2-10. TROUBLESHOOTING PROCEDURES - (CONT)
M40A1 PECULIAR (CONT)
2-34
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
M42A2 PECULIAR
2-35
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-10. TROUBLESHOOTING PROCEDURES - (CONT)
M42A2 PECULIAR (CONT)
2-36
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-37
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-10. TROUBLESHOOTING PROCEDURES - (CONT)
M42A2 PECULIAR (CONT)
2-38
-
TM 34240-346-20&PTM 09204A/09205A - 20&P/2
SECTION V. PREVENTIVE MAINTENANCE CHECKS AND SERVICES(PMCS)
2-11. INTRODUCTION TO PMCS TABLEa. General. Unit PMCS is
performed semiannually (every 6 months). The soldier may perform
semiannual PMCS
under supervision of NBC NCO or other trained person. Unit PMCS
is performed to assure that the moreexperienced NBC NCO regularly
checks that the soldier is properly doing daily PMCS. This allows
the NBCNCO to perform his responsibilities to assure that: 1. The
soldiers are properly performing their daily PMCS; 2.The soldiers
are properly performing their monthly PMCS; and 3. That the
soldiers are involved in performingthe semiannual PMCS. In addition
the NBC NCO is responsible for assuring that those checks
identified areperformed on a weekly basis during combat situations.
Semiannual PMCS and initial and mandatory fitvalidation M41 test
will be scheduled and will be recorded on DD Form 314, Preventive
Maintenance Scheduleand Record. The Semiannual PMCS will be
completely performed in accordance with the applicable
operator'smanual (TM 3-4240-346-10/TM 09204A/09205A-10) and this
TM. Marine Corps Users will perform and recordsemiannual
maintenance in accordance with procedures prescribed in TM
4700-15/1_ and unit SOP.
b. Inspections. The most detailed inspections and PMCS of the
mask is performed when it is first received, aftereach use,
semiannually and during the annual fit test. The NBC NCO is
involved in all of these inspections. Thisallows the NBC NCO to
assure that the operator is properly doing the daily PMCS.
c. WARNINGS and CAUTIONS. It is vital to the safety of the
operator and the Unit Maintenance personnel that allWARNINGS and
CAUTIONS are followed. It is also the responsibility of the NBC NCO
to make sure theoperator understands their importance and follows
them very carefully.
d. Training Materials. Training materials are available (see
Appendix A).
NOTEConduct an initial and annual fit test of all assigned masks
using the ProtectionAssessment Test System (PATS M41), if
available, banana oil, or stannic chloride.
2-12. PMCS PROCEDURES
The following paragraphs describe the information presented in
each column of the PMCS table.a. Item Number Column. Numbers in
this column are for reference. When completing DA Form 2404
(Equipment
Inspection and Maintenance Worksheet), include the item number
for the check/service indication at fault. Itemnumbers also appear
in the order that you must do checks and services for the intervals
listed. Record anyfaults that you discover before, during, or after
operation. You DO NOT need to record faults that you fix.
b. Interval. This column of your PMCS table tells you when to do
a certain check or service.c. Item to be Inspected Column. This
column identifies the item to be checked or serviced.d. Procedure
Column. This column briefly describes this procedure for performing
the check or service. Whenever
replacement or repair is recommended, reference is made to para
number for the applicable maintenanceInstruction.
e. Not Fully Mission Capable If: Column. Information in this
column only tells you what deficiencies will keep yourequipment
from being capable of performing its primary mission safely. DO NOT
use your mask if a check andservice shows a fault listed in this
column. Shortcomings or minor discrepancies which DO NOT limit
operationalcapability or safety of use may require corrective
surveillance, but does not "deadline" the mask.
f. Other Table Entries. Be sure to observe all special
information and notes that appear in your table.
NOTEAll PMCS tasks are common to both the M40A1 and the M42A2.
Therefore, all PMCStasks must be performed regardless of which mask
you have. Please note that all tasksare illustrated with the M42A2
mask, however, the procedures indicated are common.
2-39
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-12. PMCS PROCEDURES (CONT)
Table 2-3. UNIT PREVENTIVE MAINTENANCE CHECKS AND SERVICES
ITEMNO.
INTERVAL ITEM TO BECHECKED OR
SERVICED
PROCEDURE NOT FULLYMISSION
CAPABLE IF:
1 SemiannualSchedule(PMCS)*
Mask Assembly
CAUTIONDO NOT use a high pressure hose toclean mask. It may
damagecomponents.
NOTESanitizing will be done prior to reissueto another soldier
or prior to turn-in asexcess.
Make sure finish covers all metalsurfaces. Coat all bare metal
surfaceswith lacquer (item 10, APP D).
a. Check mask assembly (1) for dirt orpermanent set which may
affect fit orconformance to the face. Signs ofpermanent set are:1.
Mask assembly is difficult tospread open.2. Unusual stiffness in
sealing areaof mask assembly.
b. Check rubber next to eyelens (2) tobe sure neither eyelens
will pull awayfrom mask assembly.
Mask Assembly Maskassembly is dirty enoughto affect mask
assemblyseal or function.Mask assembly has apermanent set,
orstiffness.
Eyelens will pull awayfrom mask assembly.
COMMON
2-40
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-12. PMCS PROCEDURES
Table 2-3. UNIT PREVENTIVE MAINTENANCE CHECKS AND SERVICES
ITEMNO.
INTERVAL ITEM TO BECHECKED OR
SERVICED
PROCEDURE NOT FULLYMISSION
CAPABLE IF:
c. Pull head harness (3) over front of mask.Pull chin flap (4)
forward so you cansee under it. Look around the twoholes (5) in the
chin cup (6) for cutsor tears.
d. Hold nosecup chin flap (4) back soyou can see the internal
drink tubeconnection (7).
e. Check the internal drink tubeconnection, inside the
maskassembly to see if it is broken. If theconnection looks like
the leftillustration, replace the facepiece(para 2-26, M40A1; para
2-27,M42A2). If the connection looks likethe right illustration,
replace theinternal drink tube nipple(para 2-25).
The black silicon has anycuts or tears.
Internal drink tube nippleis broken and cannot bereplaced.
2-41
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-12. PMCS PROCEDURES (CONT)
Table 2-3. UNIT PREVENTIVE MAINTENANCE CHECKS AND SERVICES
(CONT)
ITEMNO.
INTERVAL ITEM TO BECHECKED OR
SERVICED
PROCEDURE NOT FULLYMISSION
CAPABLE IF:
1 SemiannualSchedule(PMCS)*
Mask Assembly (Cont)
f. Place thumb on sideport (8) andfingers inside mask (1). Push
upgently with thumb while pullinggently with fingers until mask
snapsup to reveal inside of mask area (9)around sideport.
g. Fold back nosecup (10) so view ofarea around sideport is
clear.Inspect area around sideport forholes, cuts or tears.
Forreplacement see para 2-26, M40A1or para 2-27, M42A2.
Mask has any holes, cutsor tears.
2-42
COMMON
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-12. PMCS PROCEDURES
Table 2-3. UNIT PREVENTIVE MAINTENANCE CHECKS AND SERVICES
ITEMNO.
INTERVAL ITEM TO BECHECKED OR
SERVICED
PROCEDURE NOT FULLYMISSION
CAPABLE IF:
WARNINGDo nut push up hard on side voicemitterretainer. The
retainer could cut thefacepiece and cause leaks.
h. Place thumb on side voicemitter(11) and fingers inside mask
(1).Push up gently with thumb whilepulling gently with fingers
until masksnaps up to reveal inside of maskarea (12) around side
voicemitter.
i. Fold back nosecup ( 10) so view ofarea around side
voicemitter isclear. Inspect area around sideportfor holes, cuts or
tears. Forreplacement see para 2-26, M40A1or para 2-27, M42A2.
Mask has any holes, cutsor tears.
2-43
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-12. PMCS PROCEDURES (CONT)
Table 2-3. UNIT PREVENTIVE MAINTENANCE CHECKS AND SERVICES
(CONT)
ITEMNO.
INTERVAL ITEM TO BECHECKED OR
SERVICED
PROCEDURE NOT FULLYMISSION
CAPABLE IF:
2
3
SemiannualSchedule(PMCS)*
Front voicemitter
Side voicemitter
a. Check Front Voicemitter (13 ) fordamage, cracks or distortion
thatmay affect voice transmission.
a. Remove side voicemitter retainer(14) by unscrewing
counterclockwise with the D-ring (15) onthe carrier. Inspect
retainer forcracks or distortion. Forreplacement see para 2-23.
b. Remove side voicemitter (16) andinspect for holes, cracks,
orwarping. For replacement seepara 2-23.
c. Remove gasket (17) and check forsplits, sticky, or compressed
areas.For replacement see para 2-23.
Front Voicemitter iscracked, damaged ordistorted.
Side voicemitter retainerhas cracks or distortion.
Side voicemitter retainerhas cracks or distortion.
Gasket is split, sticky orcompressed.
2-44
COMMON
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
SECTION VI. CONVERSION PROCEDURES
2-13. LEFT/RIGHT FILTER CANISTER/HOSE ASSEMBLY CONVERSION
THIS TASK COVERS: Conversion Instructions
INITAL SETUP:
Applicable Configurations:
M40A1/M42A2
Equipment condition:
Quick Doff Hood removed. (See Operator's Manual)
CONVERSION INSTRUCTIONS
1. Remove filter canister (I) by turning counterclockwise (M40A1
only).
2. Remove hose (2) by turning the star knob (3) counterclockwise
(M42A2 only).
CAUTIONBe careful when disconnecting buttons. The mask assembly
maybe damaged if care is not exercised.
3. Disconnect the airflow deflector (4) from mask assembly (5)
by carefully pulling the silicon rubber housing (6) awayfrom the
airflow deflector buttons (7).
2-45
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-13. LEFT/RIGHT HOSE ASSEMBLY CONVERSION (CONT)
4. Grasp a tab (8) on inlet valve body (9) and pull toward
center of inlet valve body until unsealed from sideport (10).
5. Tuck unseated portion of inlet valve body into the mask
assembly. Remove airflow deflector from mask assembly.
6. Remove side voicemitter retainer (11) by unscrewing
counterclockwise using the D-ring (12) on the mask carrier.
2-46
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
7. Remove side voicemitter (13) from mask assembly by pressing
from inside of mask assembly (5). Remove gasket(14) from sideport
(10) housing on mask exterior.
WARNINGBe sure the inlet valve body is installed on the post of
the airflowdeflector with the tabs of the inlet valve body away
from the inletvalve disk. If it is installed improperly, the mask
will leak.
8. Check that inlet valve body (9) is installed on the post of
the airflow deflector with the tabs (8) of the inlet valve bodyaway
from the airflow deflector (4).
9. Position airflow deflector in pocket on opposite side of mask
assembly.
2-47
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-13. LEFT/RIGHT HOSE ASSEMBLY CONVERSION (CONT)
CAUTIONDO NOT pull on spokes of valve body while installing.
This will break the spokesand require replacement of the valve
body.
10. With one hand push inlet valve body (9) through sideport
(10). With other hand pull on thick outer rim (15) of valvebody
until valve body is completely through sideport.
11. Push buttons (7) on sides of airflow deflector (4) into
button holes (16) in mask assembly pocket.
12. Press lightly around thick outer rim of valve body until the
valve body seats in the sideport.
2-48
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
13. Install filter canister (1) by turning clockwise.
14. Install hose (2) by turning star knob (3) clockwise.
WARNINGBe sure the side voicemitter is installed with the flange
and fourbeads facing out. If installed incorrectly it could cause
the maskassembly to leak.
15. Position gasket (14) in sideport (10).
16. Install side voicemitter (13) with four beads (17) facing
out..
17. Position side voicemitter retainer (I 1) in sideport.
2-49
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-13. LEFF/RIGHT HOSE ASSEMBLY CONVERSION (CONT)
18. Tighten voicemitter retainer (11) by turning clockwise with
the D-ring (12) on the mask carrier strap.
19. Check for proper function (para 2-8).
2-50
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-14. M40A1 TO M42A2 CONVERSION
THIS TASK COVERS: Conversion Instructions
INITIAL SETUP:
Applicable Configurations:
M40A1
Equipment condition:
Quick Doff Hood removed. (See Operator's Manual)
Materials/Parts:
Detachable MicrophoneHose AssemblyCanister CarrierCombat Vehicle
Mask Carrier
CONVERSION INSTRUCTIONS
1. Remove filter canister (1) (see Operator's Manual).
2. Install hose assembly (2) (see Operator's Manual).
3. Install filter canister in canister carrier (3) (see
Operator's Manual).
4. Install detachable microphone (4) (see Operator's
Manual).
5. Stow mask in combat vehicle mask carrier and turn in field
mask carrier.
2-51
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-15. M42A2 TO M40A1 CONVERSION
THIS TASK COVERS: Conversion Instructions
INTIALSETUP:
Applicable Configurations:
M42A2
Equipment condition:
Quick Doff Hood removed. (See Operator's Manual)
Materials/Parts:
Field Mask Carrier
CONVERSION INSTRUCTIONS
1. Remove hose assembly (1) (see Operator's Manual).
2. Remove filter canister (2) from canister carrier (3) (see
Operator's Manual).
3. Remove detachable microphone (4) (see Operator's Manual).
4. Install filter canister by turning clockwise (see Operator's
Manual).
5. Stow mask in field mask carrier and turn in combat vehicle
mask carrier, detachable microphone, and canistercarrier.
2-52
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
SECTION VII. MAINTENANCE PROCEDURES
2-16. GENERAL
a. The maintenance procedures in this section are to be
performed by a unit NBC NCO or by the user under unitNBC NCO
supervision.
b. This section is divided into those tasks which are common to
the M40A1 and the M42A2, those tasks whichare peculiar to the M40A
1, and those tasks which are peculiar to the M42A2. Common tasks
are illustratedwith the M42A2.
c. This section contains detailed instructions for replacing the
following components.
Para. Page
COMMON TASKS
2-17. INTERNAL
DRINKTUBE.......................................................................................................................................2-54
2-18. QUICK DISCONNECT COUPLING, EXTERNAL DRINK
TUBE.............................................................................2-56
2-19. HEAD
HARNESS..................................................................................................................................................2-57
2-20. NOSECUP VALVE
DISKS.....................................................................................................................................2-58
2-21. AIRFLOW DEFLECOR, INLET VALVE, AND VALVE
BODY..................................................................................2-59
2-22. OUTLET VALVE COVERAND OUTLET VALVE
DISK...........................................................................................2-63
2-23. SIDE VOICEMITTER, VOICEMlTTER RETAINER, AND
GASKET........................................................................2-65
2-24. INTERNAL DRINK TUBE
NIPPLE........................................................................................................................2-66
2-25. OPTICAL INSERT
KIT..........................................................................................................................................2-68
M40A1 PECULIAR TASKS
2-26. M40A1
FACEPIECE..............................................................................................................................................2-73
M42A2 PECULIAR TASKS
2-27. M42A2
FACEPIECE..............................................................................................................................................2-74
2-28. CLAMP
COVER....................................................................................................................................................2-75
2-29. PORT
GASKET.....................................................................................................................................................2-76
2-53
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
COMMON
2-17. INTERNAL DRINK TUBE
THIS TASK COVERS: a. Removal b. Installation c. Checking for
Fit
INITIAL SETUP:
Applicable Configurations:M40A1/M42A2
Materials/Parts:Shears (item 14, app D)
a.REMOVALCAUTION
Do not scratch plastic eyelens while performing maintenance
procedures.
NOTEThere are two types of internal drink tubes. The original
drinktube and a revised drink tube which is used only when the
drinktube nipple has been replaced. Both are illustrated.
1. Lay mask assembly (1) face down on nonabrasive surface.
2. Grasp internal drink tube (2) at drink tube coupling (3) and
pull internal drink tube away from coupling.
b.INSTALLATION
1. Lay mask assembly face down on nonabrasive surface.
2. Install internal drink tube on drink tube coupling and press
internal drink tube until it bottoms fully against drink
tubecoupling.
2-54
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
c.CHECKING FOR FITCAUTION
Internal drink tube will irritate lips if it touches them while
wearing maskassembly.Internal drink tube must be removed from mask
assembly prior to adjustinglength to prevent damage to mask
assembly.
NOTESlight pressure on the top of the outlet valve body
shouldenable the internal drink tube to be grasped by the
soldier'slips.
1. Have soldier put on mask assembly and check to see if
internal drink tube touches lips.
2. If internal drink tube (2) touches soldier's lips while
wearing mask assembly (1), adjust length of internal drink tubeas
follows:
a. Remove internal drink tube from mask assembly.
b. Cut internal drink tube behind first barb (4).
c. Install internal drink tube.
CAUTIONDO NOT remove the last barb, as this is needed for proper
function.
3. Repeat steps 1 and 2, if necessary, to achieve proper
fit.
2-55
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
COMMON (CONT)
2-18. QUICK DISCONNECT COUPLING, EXTERNAL DRINK TUBE
THIS TASK COVERS: a. Removal b. Installation
INITIAL SETUP:
Applicable Configurations:M40A1/M42A2
a. REMOVAL
1. Lay mask assembly (1) face up.
2. Remove quick disconnect coupling (2) from retainer (3).
3. Grasp external drink tube (4) where it joins the quick
disconnect coupling , with one hand, and with the other, graspthe
quick disconnect coupling and pull away with a twisting motion,
disengaging the external drink tube from thequick disconnect
coupling.
b.INSTALLATIONNOTE
Quick disconnect tube connection may be moistened with waterto
aid in coupling it with the rubber tubing.
1. Lay mask assembly face up.
2. Insert quick disconnect coupling into the external drink tube
and, with a twisting motion, press drink tube in place.Ensure tube
extends over the nipple end of the quick disconnect by 5/8 - 3/4
inch.
3. Verify drink system for leaks in accordance with para
2-9.
4. Reinstall quick disconnect coupling in retainer.
5. Check for leaks in accordance with para 2-9.
2-56
-
TM 3-4240-346-20&PTM 09204A/09205A 20&P/2
2-19. HEAD HARNESS
THIS TASK COVERS: a. Removal b. Installation
INITIAL SETUP:
Applicable Configurations:M40A1/M42A2
a. REMOVAL
CAUTIONDo not scratch plastic eyelens while performing
maintenance procedures.
Work head harness straps (1) out of buckles (2).
b. INSTALLATION
NOTEElastic webbing that joins the two forehead straps must be
onoutside to avoid hot spots on head.
1. Position head harness (3) in mask assembly (4) with head
harness straps next to buckles and tab (5) down.
2. Work head harness straps into buckles and pull through
approximately 1 in. (2.5 cm) so that head harness strapends are
outside.
3. Stretch head harness away from mask assembly and check that
buckles hold head harness straps tightly.
4. Perform Initial Fitting Procedures. (para 2-7)
2-57
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/
COMMON (CONT)
2-20. NOSECUP VALVE DISKS
THIS TASK COVERS: a. Removal b. Installation
INITIAL SETUP:
Applicable Configurations:M40A1/M42A2
a. REMOVAL
CAUTIONDo not scratch plastic eyelens while performing
maintenance procedures.
To avoid tears, do not stretch rubber more than necessary to
remove or installparts.
1. Pull head harness (1) over front of mask assembly (2).
2. Curl back lip of nosecup (3) to expose nosecup valve seat (4)
and valve disk (5).
3. Pull nosecup valve disk out of each nosecup valve seat from
inside of nosecup.
b. INSTALLATIONNOTE
It may be necessary to pull on nosecup valve disk stem
fromoutside of nosecup while pressing it into the nosecup valve
seatfrom inside of nosecup.
Moisten the stem of nosecup valve disks with water to aid
ininstallation.
1. Press nosecup valve disk into nosecup valve seat from inside
of nosecup until nosecup valve disk is flat againstnosecup valve
seat and the stem (6) slips completely through the hole (7) in the
nosecup valve body.
2. Gently rotate nosecup valve disk to make sure it is
completely seated.
3. Repeat steps 1. and 2. to install remaining nosecup valve
disk.
4. Return head harness to its original position.
2-58
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
2-21. AIRFLOW DEFLECTOR, INLET VALVE, AND VALVE BODY
THIS TASK COVERS: a. Removal b. Installation
INITIAL SETUP:
Applicable Configurations:M40A1/M42A2
Equipment Condition:Hose removed (M40A1/M42A2)Canister carrier
removed (M40A1/M42A2)Quick Doff Hood Removed (M40A1/M42A2)
a. REMOVAL
CAUTIONDo not scratch plastic eyelens while performing
maintenance procedures.
Be careful when disconnecting buttons. The mask assembly may be
damaged ifcare is not exercised.
1. Disconnect the airflow deflector (1) from mask assembly (2)
by carefully pulling the silicon rubber housing awayfrom the
airflow deflector buttons (3).
2. Grasp a tab (4) on inlet valve body (5) and pull toward
center of inlet valve body until unseated from sideport (6).
2-59
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
COMMON (CONT)
2-21. AIRFLOW DEFLECTOR, INLET VALVE, AND INLET VALVE BODY
(Cont)
a. REMOVAL (Cont)
3. Tuck unseated portion of inlet valve body (5) into the mask
assembly. Remove airflow deflector (1) from maskassembly (2).
4. Grasp inlet valve body with thumb under two spokes (7). Pull
and peel off airflow deflector post (8).
5. Pull inlet valve disk (9) from airflow deflector post.
2-60
-
TM 3-4240-346-20&PTM 09204A/09205A - 20&P/2
b. INSTALLATION
WARNINGBe sure the inlet valve body is installed on the post of
the airflowdeflector with the tabs of the inlet valve body away
from the inletvalve disk. If it is install improperly, the mask
will leak.
NOTEThere are two sizes of deflectors. Ensure that the deflector
sizematches the mask size.
1. Position inlet valve disk (9) on lower groove (10) of airflow
deflector post (8).2. Position the inlet valve body (5) on the
airflow deflector post. Be sure that the tabs (4) of the inlet
valve body face
away from the inlet valve disk.3. Position airflow deflector (1)
in pocket on side of mask assembly.
CAUTIONDO NOT pull on spokes of inlet val