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Vehicle
Fire Suppression Systems
Frequently
Asked Questions (FAQs)
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- 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).
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