Vehicle Fire Suppression FAQs

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Vehicle Fire Suppression Systems
Frequently Asked Questions (FAQs)

Are automatic fire suppression systems with integral vehicle shutdown required for all off-road vehicles?
Can six-nozzle, 30 lb. systems be used on excavators?
Can LT-A-101-30's be used to protect vehicles used in terminal areas at airports (i.e., de-icers, baggage carriers, tow trucks, etc.)?
Do fuel tanks require protection?
When utilizing automatic vehicle shutdown, how will a vehicle operator be able to find a safe position for the machine before shutdown occurs?
When Designing Fire Protection for Large Excavators does ANSUL® require an LVS™ Wet Chemical System in conjunction with an A-101™ Dry Chemical System?
How Many LVS Tanks should be Used on an Excavator and is the LT-A-101-30 Agent Tank the optimum sized Dry Chemical Tank that should be Used on a Large Excavator?

Are automatic fire suppression systems with integral vehicle shutdown required for all off-road vehicles?
The A-101 vehicle fire suppression system is FM approved to suppress fires on off-road vehicles. As an option, a CHECKFIRE® SC-N detection and actuation system is available. Except for some underground coal mining operations, there is no requirement for automatic operation of the fire suppression system or vehicle shutdown. ANSUL, however strongly recommends automatic operation and vehicle shutdown. Automatic operation will not only actuate the system, but will also offer a warning to the operator that a fire may exist. Fires normally occur when a fuel or hydraulic line or connection breaks and sprays atomized fuel on a superheated turbo-charger or exhaust manifold. As long as the engine continues to operate, atomized fuel will continue to discharge. Therefore, engine shutdown is a must.
Can six-nozzle, 30 lb. systems be used on excavators?
Six-nozzle systems are acceptable in certain limited applications. However, in high hazard applications, ANSUL recommends four-nozzle 30 lb. systems, or the use of the larger 125 lb. or 250 lb. tanks. Both four-nozzle and six-nozzle systems will suppress fires when ideal conditions exist. However, vehicle fire protection is generally used in some of the worst operating conditions. In applications where hazard areas are totally enclosed, a six-nozzle system may be adequate. But in engine compartments (especially open compartments) only four-nozzle systems should be used. – Four-nozzle systems offer additional chemical at each nozzle with a longer discharge time. In certain large excavator applications, extended dry chemical discharge, as well as twin agent system design will be required.
Can LT-A-101-30's be used to protect vehicles used in terminal areas at airports (i.e., de-icers, baggage carriers, tow trucks, etc.)?
The LT-A-101-30 system utilizes FORAY® Dry Chemical (monomonium phosphate) as the extinguishing agent. This chemical may cause corrosion when in contact with aluminum, which is the metal used in aircraft construction. Fire suppression utilized in the terminal areas normally use a potassium bicarbonate dry chemical, Purple-K. This is the chemical used in the LT-K-101-30 system which has been widely accepted for use for the protection of these types of vehicles.
Do fuel tanks require protection?
Although fuel and hydraulic tanks on large pieces of machinery may contain several hundred gallons of flammable liquids, the tanks themselves are generally not protected. This is because the fuel is totally enclosed in the tanks and unable to burn unless the tank is ruptured or a connection is leaking. The LT-A-101 Dry Chemical system is not designed to suppress explosions or fires created by it. Fuel and hydraulic tank protection is generally limited to fuel lines and connections, tank fill connections and vents. Suppression at tank connections should be successful, unless the tank has either ruptured, has not been vented or flammable burning liquid spraying into unprotected areas has resulted in reflash.
When utilizing automatic vehicle shutdown, how will a vehicle operator be able to find a safe position for the machine before shutdown occurs?
Vehicle shutdown can be accomplished electrically using the shutdown relay in the CHECKFIRE® SC-N control unit and/or with a pressure switch. The pressure switch will not operate until the system discharges. If the fire suppression system is manually operated or if the CHECKFIRE® Series I system is being used, a pressure switch should be included to shut down the vehicle (the Series I unit does not have integral shutdown capability). If the CHECKFIRE® SC-N control unit is used, there is an integral shutdown relay that can be utilized. This shutdown relay will operate at the end of an alarm time delay that can be set for up to 30 seconds after the initial alarm. This time delay can be reset simply by pushing the delay button on the front of the unit, which will restart the time delay. This time delay period can be reset continually until a safe position is found for the machine.

NOTE: ANSUL recommends using a pressure switch in addition to the CHECKFIRE SC-N control unit, even though shutdown is utilized at the control unit. This will assure vehicle shutdown when the automatic system is actuated manually. Manual actuation will not initiate operation of the control unit!
When Designing Fire Protection for Large Excavators does ANSUL require an LVS™ Wet Chemical System in conjunction with an A-101™ Dry Chemical System?
Yes, the twin agent concept is excellent protection for large excavators. The benefit of dry chemical is rapid fire knockdown and effective cooling and blanketing of the fuel by the LVS Wet Chemical System.

How Many LVS Tanks should be Used on an Excavator and is the LT-A-101-30 Agent Tank the optimum sized Dry Chemical Tank that should be Used on a Large Excavator?
The size of the excavator will dictate how many and what sized LVS tanks will be used. The LVS system is available in (2) tank sizes (with 15 gallon or 30 gallon capacities). The LVS system allows the use of 3 or 4 nozzles connected to the 15 gallon, LVS-15 tank, or 6 or 8 nozzles connected to the 30 gallon, LVS-30 tank, depending on the application. When cooling turbochargers, a minimum of (2) nozzles must always be used for each turbocharger. Two (2) nozzles from a 4 nozzle LVS-15 or 8 nozzle LVS-30 system may be utilized for turbochargers up to 10 in. in diameter. For turbochargers larger than 10 inches, the maximum number of nozzles per tank must not exceed 3 nozzles with the LVS-15 tank and 6 nozzles with the LVS-30 tank. In addition, all other areas that can become superheated to temperatures close to or in excess of 850 °F (454 °C) must also be considered.

Larger dry chemical tanks are recommended to be used in place of the typical LT-A-101-30 agent tank on larger vehicles. The LT-A-101-250 accommodates 16 nozzles (extended discharge), 24 nozzles (standard discharge), and the LT-A-101-125 accommodates 8 nozzles (extended discharge), 16 nozzles (standard discharge).