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SECTION 1DESCRIPTION
Filtration and wall -building properties of drilling fluids and
cement slurriesare determined by a filter press. The filtration
rate is a measure of fluidloss measured in milliliters [1
milliliter (ml) = 1 cubic centimeter (cm]under 100 pounds per
square inch (psi) (690 kPa) of pressure through aspecial filter
paper for 30 minutes. Wall -building characteristics
aredemonstrated by the thickness and consis tency of the filter
cake (theresidue) deposited on the filter paper at the end of this
period. The filtercake is measured to the closest 1/32" (0.8
mm).
The low pressure filter press assemblies described in this
booklet consist
of a filter cell mounted in a frame, a pressure source, a
filtering medium,and a graduated cylinder for receiving and
measuring the filtrate.
The filter cell, or drilling fluid cell, is constructed of
rustproof anodizedaluminum and chrome plated brass, or stainless
steel.
Pressure sources deliver the required 100 5 psi (690 35 kPa) and
mayconsist of compressed nitrogen or air in cylinders, CO 2gas
cartridges,high pressure air or water systems, or a dead -weight
hydraulic pressure
assembly.
CAUTION
DUE TO THE HAZARD OF EXPLOSION, COMPRESSEDOXYGEN SHOULD NOTBE
USED AS A PRESSURE SOURCE.
The filtering medium normally is a filter paper that has been
speciallyhardened for filtrate testing. The filtrate receiver is a
10 or 25 ml graduated
cylinder.
NOTE: A filtration Reduction Evaluation Device (FREAD) is
available foruse in the Model 300 filter presses. This device
adapts the filterpress cell to hold a 1/4 inch (6.3 mm) porous
ceramic filter whichreplaces the filterpaper.
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SECTION 2SAFETY CONSIDERATIONS
Safe operation of Filter Presses requires that the laboratory
technician ordrilling fluids engineer be familiar with the proper
operation and potentialhazards associated with this equipment.
Pressurizing the drilling fluidsample cell poses the potential
hazards of the cell or associatedpressurization equipment leaking
and releasing sample or pressurizingfluid which could cause serious
injury. Several precautions that should beobserved are listed
below:
1. Always use either Nitrogen, Carbon Dioxide, or compressed
air.Never connect the Filter Press to Oxygen, natural gas, or
any
other non -recommended gas. If Nitrogen is used it must
besupplied from an approved Nitrogen gas cylinder.
NitrogenCylinders must be secured and meet all safely standards.
CarbonDioxide is normally supplied in small cartridges which
containabout 900 psi (6206 kPa) pressure. They are primarily used
forfield operations. Do not allow these cartridges to be heated
orexposed to fire. They can explode if overheated. If comp ressed
airis used, its maximum pressure should not exceed 150 psi
(1035kPa).
2. Maintain pressure regulators in good condition. Never use oil
onpressure regulators. Leaking pressurization systems should
berepaired or replaced. Gauges, fittings and ho ses should be kept
ingood condition and leaks should be found and
corrected.Periodically test the safety relief valves on the
pressurizationmanifolds to verify they will relieve if excessive
pressure shouldoccur. Never plug or bypass these safety val
ves.
3. When pressurizing the Cell always make sure the regulator
isclosed (Tee screw backed all the way out, counterclockwise),
thenopen the supply pressure, then adjust the regulator. Do
notattempt to pressurize higher than 100 psi. (694 kPa). Fol low
theprocedure as outlined in Section 3-A and 3-B. When de
-pressurizing, shut off the supply pressure, bleed the system
ofpressure, then back out the regulator Tee screw following
theprocedures in Section 4, Step 7 or Section 5, Step 8.
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Fig. 1 CO2CARTRIDGE HOLDER ASSEMBLY
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SECTION 3FILTER PRESS PRESSURE SOURCES
A. CO2CARTRIDGE PRESSURE SOURCE
Follow this procedure to pressurize the filter press with a CO
2cartridge pressure source (Refer to Fig. 1)
1. Remove the barrel f rom the CO 2pressuring assembly andinsert
a fresh CO 2cartridge.
2. After making sure the safety bleeder valve is closed, andthe
regulator adjusting screw is backed out to the closed
position (maximum outward), turn the barrel loosely withthe
fingers until first contact with the puncturing pin is felt.
3. Advance the holder an additional 1/4 turn. The puncturepin,
shown in Fig. 1, seals when the cartridge seats.
4. Screw the adjusting screw into the regulator to apply 100 5
psi(690 kPa) pre ssure to the filter cell as indicated by the
test-pressure gauge. Start 30-minute timing now.
CAUTION
WHEN USING SYSTEMS WITH CO 2CARTRIDGES AS APRESSURE SOURCE, NO
INLET PRESSURE GAUGEOR VALVE IS USED. USE CARE WHEN REPLACINGSPENT
CO 2CARTRIDGES . THERE COULD BE SOMEPRESSURE LEFT IN THE CARTRIDGE.
KEEP CO 2
CARTRIDGES AWAY FROM EXTREME HEAT.
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B. NITROGEN CYLINDER PRESSURE SOURCE
Follow this procedure t o pressurize the filter press with a
Nitrogencylinder pressure source (Refer to the assembly in Fig.
2):
1. With the regulator adjusting screw backed out to theclosed
position (maximum outward), slowly open thepressure valve on the
cylinder. The inle t pressure gaugeshould show the cylinder
pressure. Be sure this isgreater than 100 psi, (690 kPa).
2. Be sure the hose between the cylinder regulator and thecell
is connected, all fittings are tight, and the safety -bleeder valve
is closed.
3. Screw the regulator adjusting screw into the regulator
toapply 100 5 psi (690 kPa) pressure to the filter cell,
asindicated by the test -pressure gauge. Start 30 -minutetiming
now.
CAUTION
ALWAYS SCREW THE REGULATOR ADJUSTINGSCREW TO ITS MAXIMUM OUTWA
RD POSITIONBEFORE OPENING THE RELEASE VALVE ON THEPRESSURE SOURCE.
IF THE FULL PRESSURE OFTHE PRESSURE SOURCE IS RELEASED TO AN
OPENREGULATOR, THE REGULATOR IS PUT UNDER ASEVERE STRAIN. IF THIS
CAUSES THE REGULATORTO FAIL, THE FULL TANK PRESSURE IS RELEASEDTO
THE FILTER PRESS AND IT MAY BE DAMAGED.
AS AN ADDED PRECAUTION, A SAFETY BLEEDERVALVE, THAT RELEASES AT
APPROXIMATELY 170PSI, IS PLACED IN THE SYSTEM BETWEEN THEREGULATOR
AND THE FILTER PRESS.
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C. DEAD-WEIGHT-HYDRAULICS PRESSURE SOURCE
The Dead -Weight-Hydraulic Filter Press is a Series 300
FilterPress equipped with a Dead-Weight Hydraulic Assembly. Refer
toFig. 3. The Dead Weight Hydraulic Assembly is shown in Fig.
4.
Follow this procedure to pressurize the filter press with the de
ad-weight-hydraulic pressure source:
1. Fill the water reservoir and cylinder of the dead
-weightassembly to the top with clean fresh water.
2. Open the bleed -off valve and place the piston, with
theweight attached, in the cylinder. Allow the piston to travelfull
stroke.
3. Refill the reservoir with clean, fresh water and close
thebleed-off valve.
4. Set the unit in place on the filter press frame and
tightenthe attaching set screws, if not previously attached.
5. Connect the air hose from th e dead -weight assembly to
the top cap pressure inlet, if not previously attached.
6. Raise the weight to the top of its stroke and allow it
tosettle. In about two -thirds of the stroke, the deliverypressure
gauge will indicate 100 psi.
7. Lift the de ad weight back to the top of the stroke. Startthe
timing of the test when the weight is released. Onestroke of the
piston will allow a maximum filtration loss of
approximately 30 ml.
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D. EXTERNAL PRESSURE SOURCE
Almost any compressed air source, with a reliable pressure
ofmore than 100 psi, (690 kPa) is suitable to pressurize the
filter
press. However, there must be a suitable regulator, on this line
sothat the pressure to the cell can be regulated. A regulator such
as33700 or 34265 is suitable. A shutoff valve and a hose should
beinstalled between the regulator and the filter press cell. Refer
toFigs. 5 and 6 and the following Note.
NOTE: The 33700 regulator is designed for amaximum inlet
pressures of 1000 psi,(6940 kPa.) and the 34265 regulator
isdesigned for inlet pressures between1000 psi (6940 and 3000 psi
(20820kPa).
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Fig. - CO2PRESSURE ASSEMBLY,EXPLODED VIEW
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SECTION 4STANDARD FILTER PRESS TEST PROCEDURES
Follow the steps in this procedure to operate the filter press
with a
compressed gas or dead-weight hydraulic pressure source:
1. Assemble the clean, dry parts of the filter cell in the
following orderRefer to Fig. 7:
a. base capb. rubber gasketc. screend. a sheet of filter papere.
rubber gasketf. filter cell
2. Secure the cell to the base cap by rotating it clockwise.
3. Fill the cell with the test sample to within approximately
1/4"(6mm) of the top. (Filling the cell to this level lessens the
volumeof pressurizing gas required from the pressure source.)
4. Set the filter press cell assembly in place within the
frame.
5. Check the top cap to make sure the rubber gasket is in
place.Place the top cap, already connected to the pressure source,
ontothe filter cell and secure the cell in place with the T
-screw.
6. Place a dr y graduated cylinder under the filtrate tube,
either on thesupport or in the clip.
7. Depending upon the pressure source being used, apply
pressure
to the cell following the appropriate pressure source procedure
asoutlined in Section 3.
8. At the end o f 30 minutes (or 7 -1/2 minutes - Refer to Note
below),close the pressure source valve and back off the regulator,
openthe safety-bleeder valve. This releases the pressure on the
entiresystem.
9. Measure the volume of filtrate collected in the graduate d
cylinderand record the filtrate loss in milliliters as the API (30
minute)filtrate loss of the drilling fluid, or milliliters x 2 for
the 7 -1/2 minutetest.
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NOTE: The amount of filtrate collected after 7 -1/2 minutes can
benoted and, when this amount is multiplied by two, it willgive a
rough estimate of the amount that will be collectedin 30 minutes.
The estimated valve is usually one or moremilliliters short of the
actual valve and this estimation
procedure should not be attempted on drilling flu ids havinga
filtrate loss of less than 5 ml in the 7 -1/2 minute period.
10. Loosen the T-screw, remove the cell top, and then remove the
cellfrom the frame.
11. Discard the drilling fluid.
12. Disassemble the filter cell and carefully remove the filte r
cake andfilter paper from the base cap.
13. With a gentle steam of water (or, in the case of oil
drilling fluids,with clean base oil), carefully wash excess
drilling fluid from thecake.
14. Measure and record the thickness of the filter cake to the
nearest1/32" (0.8 mm).
15. If desired, record properties of the filter cake such as
texture,hardness, flexibility, etc.
Fig. - FILTER PRESS AND CELL ASSEMBLY, EXPLODED VIEW
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SECTION 5FREAD FILTER PRESS TEST PROCEDURES
Follow this modified procedure if the FREAD ceramic disc adapter
is to beused. Either compressed gas or the dead -weight-hydraulic
unit can beused.
1. Assemble the Filtration Reduction Evaluation Device as
follows,Refer to Fig. 8:
a. Assemble the selected porosity ceramic filter disc into
theBody Adapter (1).
b. Assemble "O" ring seal (5) into the Body Adapter.
c. Install Ring Seal (2) into Body Adapter fitting it over
the"O" ring.d. Screw the Seal Nut (3) onto the Body Adapter (1)
and
tighten hand tight.e. Install "O" Ring (4) on the outside bottom
of the Body
Adapter.
2. Assemble the dry parts of the filter cell in the following
order.Refer to Fig. 7 and Fig. 8 omitting filter paper and screen
from Fig.
7.
a. base capb. rubber gasketc. FREAD assembly. Refer to Procedure
1 above.d. rubber gaskete. filter cell Secure the cell to the base
cap by rotating it
clockwise.
3. Fill the cell with the test sample to within approximately
1/4"(6mm) of the top. (Filling the cell to this level les sens
thepressure volume required from the pressure source.)
4. Set the filter press cell assembly in place within the
frame.
5. Check the top cap to make sure the rubber gasket is in
place.Place the top cap, already connected to the pressure source,
o ntothe filter cell and secure the cell in place with the T
-screw.
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6. Place a dry graduated cylinder under the filtrate tube,
either on thesupport or in the clip.
7. Depending upon the pressure source being used, apply
pressureto the cell following the appropriate pressure source
procedure as
outlined in Section 3.
8. At the end of 30 minutes close the pressure source valve and
backoff the regulator, open the safety -bleeder valve. This
releases thepressure on the entire system.
9. Measure the volum e of filtrate collected in the graduated
cylinderand record the filtrate loss in milliliters as the 30
minute filtrateloss of the drilling fluid using the FREAD adapter
and the micronsize of the filter used for the test.
10. Loosen the T-screw, remove the cell top, and then remove the
cellfrom the frame.
11. Discard the drilling fluid.
12. Disassemble the filter cell and carefully remove the
FREAD
assembly with the cake.
13. With a gentle steam of water (or, in the case of oil
drilling fluids,with diesel oil), carefully wash excess drilling
fluid from the cake.
14. Measure and record the thickness of the filter cake to the
nearest1/32" (0.8 mm) and note that this test used the FREAD.
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SECTION 6CARE OF EQUIPMENT
A. Cleaning
After each use, the filter press cell should be disassembled
andcleaned of all drilling fluid by washing and thoroughly
rinsing.Wipe off the rest of the filter press, and dry all p arts
completely.Replace the filter paper on the screen, and assembly the
end caponto the cell. Loosely reassemble the cell onto the frame
forstorage.
B. Pressure Regulator Maintenance and Repair
Most regulator troubles are caused by leaking fitting s or
faulty pinsand seats. Rarely does a diaphragm rupture. If regulator
will nothold pressure, check the fittings which are screwed into
it. This isdone by applying pressure to the system and looking for
escapinggas in the form of bubbles. There a re two methods of doing
this.One method is to apply soap suds to the fitting areas, the
other isto carefully immerse all but the pressure gauge in a
container ofwater. If leaks are apparent, disassemble and apply
tape thread
sealant to the threads.
CAUTION
DO NOT USE OIL BASED THREAD DOPE OR OILWHEN ASSEMBLING ANY
REGULATOR.
Replacing the seat and pin.
If regulator connections do not leak, the seat and pin
probablyneed replacement. Use the following procedure. Refer to
itemson Fig. 5 and 6.
1. Using a wrench on the hex of the spring case, unscrewthe
spring case. All parts down to and including thediaphragm will
remain in the spring case.
2. Remove the thrust plate.
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3. Unscrew the retainer and remove the seat with the pin.
4. Clean and inspect the regulator for evidence of dirt
ordrilling fluid in the regulator body. An outlet filter (33720)is
available to prevent this problem.
5. Replace the pin and seat.
6. Re-assemble the regulator.
C. Dead Weight Hydraulic Unit Maintenance
Always protect the mirror finish of the stainless steel
piston,especially when removing it. Clean the fine mesh screen on
thebottom of the water reservoir. If the piston moves sluggishly
duringa test, remove the piston and O -ring from the cyli nder.
Clean theO-ring groove in the cylinder. Examine the O -ring
carefully for tornor rough places, and, if the surface is damaged,
replace it with anew O-ring. Before replacing the O -ring and the
piston, apply alight film of high -grade, water -repellent grease.
In subfreezingweather, the water in the dead -weight assembly can
be replacedby an anti -freeze solution such as ethylene glycol and
water; this
does not adversely affect the operation of the unit.
Fig. - FILTER PRESS, STANDARD FRAME