Fire officer handbook of tactics chapter 20

• Emergency responses often involve incidents where there's no fire or the fire is contained.
• Gas leaks are among the most common and potentially deadly emergency responses.

Natural Gas Composition and Properties

• Natural gas is primarily methane (over 90%) with smaller amounts of ethane (up to 5%), carbon dioxide, and nitrogen.
• Ethane presence helps fire departments/utilities locate natural gas leaks, differentiating from swamp gas or hydrocarbon vapors.
• Natural gas is naturally colorless and odorless; mercaptan-based odorant is added for leak detection at a concentration of 1% in air.
• Odorant can dissipate over long distances in pipelines, requiring reapplication at local utility connections.
• Odorant leaks are flammable liquid spills with a strong smell, undetectable by combustible gas indicators.
• Vapor density is 0.60, so it should rise rapidly.

Natural Gas Emergency Categories

• Inside leaks pose the greatest explosion risk.
• Outside leaks can migrate and collect in buildings or manholes, risking explosions.
• Ignited gas is the least dangerous, with minimal explosion potential.

Distribution Systems

• Transmission pipelines operate at 350–850 psi, monitored remotely, and can cause large fires if ruptured.
• Pipeline operators can remotely isolate leaks using remote-control valves.
• Evacuate, protect exposures, and check buildings for gas seepage during pipeline leaks.
• Do not attempt to close valves without pipeline personnel guidance.
• City gate stations reduce pressure to 60–150 psi, followed by district regulator stations for distribution systems.
• Older low-pressure systems operate at ¼ psi with no further reduction.
• Newer high-pressure systems range from 2½ to 60 psi, requiring regulators at each building to reduce pressure to ¼ psi.
• Regulator failure can cause excess pressure, igniting nearby combustibles or extinguishing pilots, leading to gas buildup.
• Regulators located inside a building have the vent line piped outside.
• Actions for regulator failure include notifying the utility, shutting off gas, searching for fire extension/victims, and venting.
• Natural gas displaces oxygen, causing asphyxiation; manufactured gas used in the past contained carbon monoxide.

District Regulator Failure

• Failure increases pressure, causing gas-related fires, leaks, and explosions across a large area.
• Example: Chicago had building failures in an 11-square-block area due to district regulator failure.
• Fire departments will need notification capabilities and incident location information.
• Utility companies may know about failures via remote pressure-monitoring devices.
• Request additional resources, set up a staging area, and use public address systems/media to notify occupants to turn off gas appliances and evacuate.
• Shutting down gas services to every building within the area is necessary.
• Specialized units are needed to enter and shut off gas services, requiring forcible-entry tools and SCBA.
• Every structure must be searched for victims, especially during sleeping hours.

Tactics for Inside Leaks

• Notify the utility and determine ETA.
• Determine leak intensity and when it was noticed.
• Determine the extent of evacuation required.
• Eliminate ignition sources.
• Locate the source and stop the flow.
• Search and ventilate.
• Dispatchers should determine the smell of gas and when it was first noticed to advise callers.
• Use a combustible gas detector to determine dangers, as odorant may be filtered.
• TIF 8800 detector is useful to pinpoint gas leaks.
• For faint odors, check pilot lights first.
• Use soapy water to confirm presence of gas.
• Isolate the leak close to the source using quarter-turn appliance valves or meter wing cocks.
• Service entrance cocks can shut off gas to all tenants in multiple-tenant occupancies, but use with discretion.
• Natural gas's flammable range is 4%-14% in air.
• Don't throw switches, ring doorbells, or use non-intrinsically safe radios/cell phones in gaseous areas.
• Disconnect power only if safe by tripping main breaker remotely or cutting service entrance wires outside.
• Do not pull the meter due to potential ignition.

Venting Procedures

• Vent at upper areas, including attics, thoroughly but without unnecessary damage.
• Opening windows is generally sufficient.
• Positive pressure ventilation is more effective than using smoke ejectors.
• Limit personnel inside.
• Begin venting as soon as possible considering leak size, ignition sources, and gas-air mixture status.
• Stop leaks inside or outside after risk assessment and presence of life hazards.
• Use minimum people, SCBA, forcible-entry tools, explosion-proof lights/radios, and pipe wrench.
• Maintain a long hoseline.
• Position apparatus for shielding effect.

Tactics at Outside Leaks

• Gas migrates along service pipes/underground lines into buildings/manholes.
• Gas can be deodorized as soil filters odorant, migrating long distances.
• Combustible gas indicator is the only way to safely check areas.
• Winter promotes horizontal migration when the frost line penetrates.
• Check basements of surrounding buildings, especially service line entry points.
• Position apparatus away from manholes.

Contractor Dig-Ups

• Notify the utility
• Approach from upwind
• Secure a reliable water source
• Evacuate all exposed personnel, stop ignition sources, and shut down equipment downwind
• Only stop leaks to save lives with water handlines and dry chemical extinguishers.
• Never attempt to stop leaks in plastic pipes due to static electrical charge risks.

Tactics at Fires

• Call the utility, evacuate, protect exposures, and let fire burn until gas is shut off.
• Extinguish small fires with dry chemical/CO2 to reach valves/save lives.
• Use fog streams for larger fires to approach valves, avoiding water in trenches.
• Burning gas indoors prevents buildup and explosion.
• Cool exposed piping, extinguish combustibles, and allow gas to burn until flow stops.
• Use fog spray to cool exposures, but avoid directing the stream directly at the leak.
• Use water streams/chemicals/CO2 and control leaks by closing valves/plugging/patching when control is assured.
• Take 2½-in. hose for cellar fires.

Unusual Problems

• Heavy gas odor, no leaks found: Investigate upwind for non-gas sources.
• Odorant spill creates gas leak impression (e.g., methyl mercaptan).
• During peak demand, utilities mix in LPG, increasing vapor density; mechanical ventilation may be needed.

Liquefied Petroleum Gas (LPG) Properties

• LPG consists mostly of propane, heavier than air, and collects in low points.
• Propane has a wide explosive range: 2.1% LEL and 9.5% UEL.
• It ignites at –44°F and can create explosive concentrations almost anywhere.

Vapor-Air Explosions

• These destroy buildings, because gas spreads out and mixes with air before ignition.
• Military uses propane fuel–air explosion bombs (CBU-55).
• Buffalo, NY: A 500-lb propane tank leak caused a fuel-air explosion that leveled a building and killed six people.
• Brooklyn, NY: A 20-lb barbecue tank leak exploded, leveling buildings and killing three people.
• Many jurisdictions restrict indoor LPG storage.

LPG Cylinders

• Propane exists as liquid and gas. When compressed, gas turns into liquid, shrinking to 1/270 of its volume.
• Liquid evaporates into gas at 270 parts for each liquid part expanding.
• 1 quart of liquid propane becomes 270 quarts of vapor, producing 12,857 quarts of explosive gas–air mixture.

Boiling-Liquid, Expanding-Vapor Explosion (BLEVE)

• This is a threat to firefighters, occurring after arrival.
• Fire exposes cylinders, raising internal pressure.
• Aluminum valve handles melt away, and aluminum pressure regulators fail.
• Cylinder's relief valve shoots flames across the yard.
• Apply water stream in a fog pattern.
• A BLEVE occurs when liquid above its boiling point is suddenly released, resulting in a tremendous energy release and fireball.
• Exploding cylinders can travel great distances.
• BLEVE is a result of localized overheating weakening the steel cylinder.
• Pressure-relief valves don’t always prevent BLEVEs.
• Prevent BLEVE by keeping the metal shell from overheating through the application of cooling water.

LPG Incident Tactics

• Focus on life protection, exposure protection, and then extinguishment.
• Clear the area for at least 150 ft in all directions.
• Use all possible shielding cover to advance.
• Clear exposures in homes on either side, as well as those that adjoin the backyard
• Supply water for three or four 1½-in. or 1¾-in. handlines as first engine.
• Approach cylinders with cover and apply cooling water for at least 2 minutes.
• Selecting stream patterns requires a degree of care.
• Spring-loaded relief valves should shut off as streams cool cylinder.
• Don’t rush to close the valve manually.
• Evaluate the fire, since the cylinder has a limited fuel supply.
• Extinguish fires away from built-up areas where gas may accumulate.
• Show patience, and the fire should burn out safely.

Oil Burner Grades

• No. 1, lightest fuel oil, 100°F minimum flash point, similar to kerosene.
• No. 2, most common for homes, 100°F minimum flash point, more impurities than No. 1.
• No. 4 , used for midsized applications, 130°F minimum flash point.
• No. 5, 130°F minimum flash point, more impurities than No. 4, preheated to flow.
• No. 6, heaviest, 150°F+ minimum flash point, requires heating to burn and flow.
• Nos. 5 and 6 are industrial oils in large plants/complexes.
• Stored heavier oils use steam/hot water to preheat, caution around hot tanks/piping.

Oil Burner

• Needs heat, fuel, and oxygen to burn.
• Firebox and oil gun.
• Components are oil-handling and control systems.
• Oil-handling system: High-pressure gun atomizes oil.
• Oil is drawn from the tank through a pipeline to the oil pump in the gun, with a shutoff valve on the supply.
• High-pressure pump breaking up oil into fine particles.
• Air fan blows fresh air in.
• High-voltage electrodes create an electric arc, producing fire in the firebox.
• Firebox chamber lined with firebrick.
• Coils within the firebox transfer heat to water.
• Unused heat and gases rise into the smoke pipe.
• Control system: Starting circuit, running circuit, and safety circuit.
• Shuts down pump/fan if igniter fails after 90 seconds.

Limit Controls

• Thermostat sends a signal to the burner that fire is required.
• Pressuretrol senses pressure within a steam system.
• Aquastats found on steam and hot-water systems.
• All three controls send messages through the primary control.

Remote Control

• Cuts off all power to pump, fan, and igniter.
• Features a red cover plate.

Stack Switch

• The stack switch is designed to sense heat in the smoke pipe.
• Infrared sensor serves the same purpose on newer burners.

Smoking Burner

• Firefighters must observe chimney smoke, verify alarm cause, size-up, and shut off the emergency switch.
• Have a water supply and dry chemical extinguisher to the location of the burner area.
• Turn off the tank valve and inform the owner in writing for the need for adjustments by a qualified technician,

Delayed Ignition

• Firefighters must shut off the remote control.
• Firefighters must enter the basement to examine the area.
• Stretch a handline as a backup.
• Use AFFF/dry chemical/CO2 only if oil is burning outside the burner.
• Firefighters must ventilate the area.
• Firefighters must shut off the oil at the tank.
• Firefighters Examine the area for extension of fire
• Firefighters must advise the homeowner in writing to call a service technician.
• Firefighters should allow the fire to burn itself out, water and foam are dangerous, and may cause the box to crack.

The White Ghost

• Evacuate the entire building immediately.
• Shut down the remote control, using SCBA and a fog nozzle open in a wide pattern as protection.
• Cool the cloud, ventilate the area, use positive pressure fans, and secure ignition sources.
• Follow up by shutting off the fuel.
• The responsible person in charge of the building should be instructed to have the burner inspected by a service technician.

Roach Bombs

• Explosions are from flammable insecticide vapors when ignition sources are present.
• Be sure to turn off sources of ignition before activating the spray cylinder.
• This is sometimes overlooked, creating a flammable atmosphere.
• Often used with sulfur candles, creating a fire hazard.
• If hearing a hissing sound, withdraw and evacuate immediately since occupants may be endangered.
• Extinguish sulfur candles, vent the area, and decontaminate firefighters and gear.
• No one should be allowed to reenter the area for 12 hours after venting the area.

Smoke Origin

• Smoke volume indicates fire size.
• Smoke density indicates fire extent.
• Thin, wispy smoke indicates an incipient fire.
• Black smoke suggests petroleum-based products.
• Black smoke at the roof means involvement of roofing materials.
• Black smoke at the basement entrance indicates a defective oil burner.
• Gray to light brown smoke means Class A materials with oxygen.
• Dark gray or yellow-gray smoke means potential backdraft.
• Movement and velocity indicate fire intensity.
• Twisting smoke means hot smoke and potential flashover.
• Cold smoke means partially extinguished fires with CO.
• Wear SCBA and use a CO meter.
• The lowest floor of visible smoke has some fire; check one floor below.

Using Odor

• Check where the smell was first noticed. The distinct odor of certain fires will point firefighters in the right direction.
• Notify the dispatcher.
• Exercise caution when alerting sleeping families. If entry is required, use a fire escape.
• Announce loudly as the fire department if entering via fire escape.
• Don’t leave smoke odor incidents without locating the source.

Smoke in Larger Buildings

• Multiple reports may be from elevator/HVAC motors.
• Incinerator shaft fires block smoke/gases and require locating the blockage and removing it.
• SCBA use is mandatory due to plastics and aerosol cans.
• Compactors: Chute fires can spread and require charged lines above the fire.
• Laundry chutes can vent fires into hallways.
• Use caution in compactor rooms due to electrical/hydraulic hazards.
• Shaft fires are less likely to spread to nearby combustibles
• Chimney fires: Check for fire extension, shut off air intake, and use special extinguishers or nozzles.

Carbon Monoxide (CO) Alarms

• Treat incidents as potentially lethal.
• CO is colorless, odorless, and tasteless, detectable only with a meter.
• Dispatch EMS if flu-like symptoms (fatigue, headache, nausea, dizziness, confusion) reported.
• Testing the area with meters and testing for any flu-like symptoms in the area is necessary, and do not let the occupant back in without a thorough examination.
• Standard meters have different settings. The common meters may need to be replaced.
• Start meter readings at the front door and record all readings by ppm, location, and time.
• Check fuel-burning appliances/chimneys.
• Vent the area, inform the owner of the CO source, and require repairs.
• The building may be turned back over to the occupants if the CO levels drop to an acceptable level (9 ppm being a residence, 35 ppm being commercial)

Wood-Burning Stoves

• This can cause heavy smoke conditions and chimney fires.
• Inverse stack effect occurs during cold weather. If caught in this situation, opening a window or a door on the stove.
• Creosote fires extend through cracks.
• Shut off air intake and check for extension or use chimney fire extinguishers/dry chemical/mist nozzles.
• Avoid using standard hose streams to protect the chimney.