1 Supporting Sustainability Dennis Anderson, P.E. FM Global: Protecting the Value Your Business Creates Our Focus on Sustainability Loss Prevention Integral to Sustainability Carbon Emissions Time Disposal, Rebuild Fire Standard Construction Green Construction Demolition Operation Construction www.fmglobal.com/researchreports Risk Factors = 2-14% of CO 2 “Green” can increase by 3X
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Supporting Sustainability
Dennis Anderson, P.E.
FM Global: Protecting the Value Your Business Creates
Our Focus on Sustainability
Loss PreventionIntegral to Sustainability
Car
bon
Emis
sion
s
Time
Disposal, Rebuild
Fire
Standard Construction
Green Construction
DemolitionOperationConstruction
www.fmglobal.com/researchreports
Risk Factors = 2-14% of CO2“Green” can increase by 3X
Ammonia Refrigeration HazardsFM Global: Protecting the Value Your Business Creates
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Basic refrigeration cycle
Refrigeration – indirect systems
Compressor Package (Centrifugal)
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Compressor Package (Reciprocating)
Condenser
Receiver/Accumulator
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Expansion Valves
Evaporator (direct refrigeration)
What is ammonia?
• Refrigerant is anhydrous ammonia (NH3)– Colorless– Strong Odor
• Noticeable to humans at 15-20 ppm– Liquid heavier than water– Boils at -28oF
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What is ammonia?
Very noticeable, annoying100 Annoying, gas mask suggested200
Very annoying, gas mask needed, annoying to skin
500Toxic, cartridge mask, short time1,000
Highly toxic, full face oxygen mask, skin highly irritated
3,000 ppm (0.3%)
Effect Concentration
IIAR Operations Manual - 1987
Ammonia – key physical properties– Heat of combustion = 8000 BTU/lb – Vapors lighter than air.– LEL = 16% (160,000 ppm)– UEL = 25% (250,000 ppm)– Autoignition temp. = 1204oF– MIE much higher than hydrocarbons– Burns much slower than hydrocarbons– TLV-TWA = 25 ppm (ceiling 35 ppm)
Environmental issues
• Montreal Protocol, Clean Air Act (1987, 90)– Phase out CFC (R11 & 12) by 2000– Substitution by HCFC (R123 & 134a) & NH3
• Kyoto Protocol (1999)– Target greenhouse gases (CO2, methane)– Phase out production HCFC by 2020/2040
• Some switching to ammonia
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Codes for refrigeration systems
• ANSI/ASHRAE 15-2007, Safety Standard for Refrigeration Systems
• ANSI/ASHRAE 34-2007, Designation and Safety Classification of Refrigerants
• ANSI/ASME B31.5, Refrigeration Piping
ANSI – American National Standards InstituteASHRAE – American Society of Heating, Refrigerating, and Air Conditioning EngineersASME – American Society of Mechanical Engineers
Codes for refrigeration systems
• ANSI/IIAR 2 - 2008, Equipment, Design and Installation of Closed Circuit Ammonia Mechanical Refrigeration Systems
Component FailedElectricLeakageUnknownOptg parameterMiscellaneousHuman Element
Ammonia Loss History – Bottom Line• Cause - mechanical failure of a part due to
impact, poor installation or maintenance• Ignition - electrical equipment• Explosions - occur but usually don’t result
in huge losses• Fire following explosion - generally not
significant addition to loss• Contamination – direct refrigeration issue
What will reduce the hazard?
• Location of equipment• Construction of machine room• Arrangement of equipment• Management programs• Protection features
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What will reduce the hazard?
• Location– Never in basement– In a detached building– In a separate machine room building
• attached to an outside wall• in the building but on an outside corner• in the building on an outside wall
What will reduce the hazard?
• Location
What will reduce the hazard?
• Construction– Non-combustible– 1-hour fire rating for walls to adjacent areas– Vapor-tight walls to adjacent areas– Seal pipe openings to adjacent areas– Damage limiting (venting) construction
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What will reduce the hazard?
• Occupancy– No boilers/fired equipment in machine room– No combustible storage in machine room (lube
• Occupancy - Piping & Equipment– Seal pipe openings to adjacent areas
Protection for compressors DS 7-95• Provide relief valves on
– discharge of compressor before shutoff valves– between stages – on all pressure vessels– route discharge outside– test valves annually
• Interlocks– high pressure alarm– high temperature alarm and trip
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What will reduce the hazard?
• Ignition source control– Minimize electrics in machine room– Class I Division 2 rated electrical – Where rated retrofit not economical
• Continuous ventilation at 1 cfm/sq. ft• Emergency ventilation at 10 cfm/sq. ft• Ammonia detector (FM approved) set to alarm at
4% and shut down electrical at 8% ammonia
What will reduce the hazard?
• Protection– Sprinklers for combustible construction or
occupancy– Extinguishers– Areas with storage subject to contamination
• Visits by responsible personnel at least once per 8 hours OR
• Ammonia detector (<1000 ppm) alarming to attended location
What will reduce the hazard?
• Operation & maintenance– High level of preventive maintenance– Follow manufacturer’s guidance for frequency– Don’t step on piping during maintenance– In refrigerated areas, train lift truck operators
to avoid refrigeration system piping and components
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What will reduce the hazard?
• Emergency response– A written emergency response plan– A well-trained emergency response team– Proper emergency response equipment
Combustible Dust HazardsFM Global: Protecting the Value Your Business Creates
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Overview
• What is an explosion?• What is a combustible dust?• When does a dust explosion hazard exist?• How do dust explosions behave?• How are dust explosions mitigated?
What is an explosion?
• Rapid release of energy that produces damage
• Chemical explosion– Reaction based
• combustion reaction• decomposition
• Physical explosion– Rapid failure of vessel under pressure
What is a combustion explosion?
• This is a fire, a really, really fast fire• A fast fire requires fuel premixed with air• To develop pressure, you need confinement
– Fire increases gas temperature– Hot gas expands– If volume is fixed, pressure will rise
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How bad will it be?
What is a combustion explosion?
• Deflagrations– Flame front moves slower than speed of
sound– Uniform pressure in enclosure
• Maximum pressure 8 to 9 times ambient– Time to react and mitigate damage
• Detonations– Flame front moves at/above speed of sound– No time to react
What is a combustion explosion?
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What is a combustible dust?
• Organic material• Unoxidized metal• Other oxidizable
materials (e.g. zinc stearate)
What is a combustible dust?
• 500 microns (1/50th inch) or smaller– different materials have different size
threshold– usually range of particle sizes– fines segregation = increased hazard
• Might not burn in pile or solid form• Simple version – Did it start as a rock?
Why do dusts explode instead of burn?
• High surface to volume ratio– Instant vaporization when heated
• Air around every particle• Explosion severity is driven by
• When dust is combustible• In dust collection equipment• In buildings
– Dust suspended in air– Dust accumulated on building structure (1/16”)– Dust handling equipment
• WHEN DUST IS IN A BUILDING!!!
When is dust “suspendible”?
• Above floor level• At floor level with other explosion hazard
capable of creating disturbance– equipment explosion hazard in same area– room or equipment explosion hazard in
adjacent area
How do dust explosions behave?
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How do dust explosions behave?
• Assume explosion propagates readily between connected volumes– unburned dust is pushed ahead of expanding
cloud of burning dust– fuel rich explosion: explosion can continue as
the fireball finds new air– pressure wave moves well ahead of flame front– pressure piling effect in interconnected vessels
How are dust explosions mitigated?
• Control the dust
• Control the ignition sources
• Control the damage
How do you control the dust?• Find & eliminate fugitive dust sources• Properly design dust collection equipment• Properly maintain dust collection equipment• Pre-cleaning coarse material (remove fines)• Minimize accumulation & migration• Phlegmatization• Oil mist dust suppression• Housekeeping
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How do you minimize accumulation?H H HH H
H
How do you minimize accumulation?
H H HH H
HModify the construction
How do you control the ignition sources?10,00010,000
10001000
100100
1010
11
.1.1
.01.01
Overheated Overheated bearingsbearings
Open FlamesOpen FlamesHot SurfacesHot Surfaces
Hard to
Ignite
Hard to
Ignite
FrictionFrictionSparksSparks
ElectrostaticElectrostaticDischargeDischarge
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How do you control the ignition sources?
• Annual infrared scan of electrical equipment• Hot Work prohibition; permits when safe• Prohibit smoking and open flames• Hazardous location electrical equipment• Magnetic separators• Motion/alignment interlocks• Grounding/bonding