Flashcards in Chapter 9 - Fire Pump Theory Deck (40)
________ operate using a piston that moves back and forth in a cylinder. These multicylinder, PTO-driven pumps can provide pressures up to _____ psi for high-pressure fog lines, or to inject foam concentrate into a water line or manifold at a higher pressure than the water pump is creating.
The total amount of water than can be pumped by a rotary gear pump depends on the ______________ and _________.
Size of the pockets in the gears and the speed of rotation.
Three main factors influence a centrifugal fire pump's discharge pressure:
> Amount of water being discharged
> Speed at which the impeller is turning
> Pressure of water when it enters the pump from a pressurized source.
The increase is ______ is roughly equal to the square of the change in impeller ____. For all other factors remaining constant, doubling the ______ of the impeller will result in four times as much _______.
2x speed = 4x pressure
In parallel mode, the pump will be capable of supplying 100% of its rated capacity at ____ psi at ___ feet of lift with ___ feet of suction hose while drafting.
A very close tolerance must be maintained between the pump casing and the hub of the impeller. This opening is usually limited to ____ inch or less
The most common type of seal packing material is composed of ____________________________.
Rope fibers impregnated with graphite or lead.
The most common applications for auxiliary engine driven pumps are:
> Airport rescue fire fighting (ARFF) vehicles
> Wildland fire apparatus
> Mobile water supply apparatus
> Trailer mounted fire pumps
> Portable fire pumps
In some cases, Auxiliary Engine Driven Pumps may be part of a skid-mounted assembly that includes small water tank, booster reel, and small diameter attack lines. With a pumping capacity of generally ____ gpm or less.
In the past, conventional PTO units were limited to powering pumps up to approximately ____ gpm. However, some manufacturers now provide full torque power take-offs that allow for the installation of pumps as large as _____ gpm.
The maximum capacity of a front mounted pump depends on the limitations of the engine driving it, typically up to _____ gpm.
On mid-ship mounted pumps the gear ratio is arranged so that the impeller turns faster than the engine, usually ____ to ____ times as fast
1-1/2 to 2-1/2 times
Some mid-ship mounted pumps can be rated anywhere from ____ to _____ gpm with no major changes to the pump itself.
500 to 2,250 gpm
With the engine idling and the pump engaged, most speedometers will indicate between ___ to ___ mph.
10 to 15 mph
The rear-mount design offers a number of advantages, including _________ and ____________.
More even weight distribution on the chassis and more usable compartment space.
The primary parts of the piping system are ______ and _________ piping as well as _________ and ______.
Intake and discharge piping
pump drains and valves
Most pipes are constructed of __________, _______, ________, or ____________ and may include __________ in certain applicaitons
Cast Iron, Brass, Stainless Steel, or Galvanized Steel
The piping system and the fire pump itself must be capable of withstanding a hydrostatic test of ____ psi before being placed into service.
According to NFPA 1901, pumpers with a capacity of _____ gpm or less should have the piping capable of flowing ____ gpm. Pumpers with a capacity greater than ____ gpm should be able to flow at least ____ gpm.
<= to 500 gpm - 250 gpm
> than 500 gpm - 500 gpm
Many pumpers are equipped with tank-to-pump piping as large as __-inch in diameter
Pumps rated greater than _____ gpm capacity may require more than one large intake connection at each location.
Based on NFPA 1901, a sufficient number of 2-1/2-inch discharge openings must be provided to flow the rated capacity of the pump. As a minimum, all fire apparatus with a rated pump capacity of ____ gpm or greater must be equipped with at least ___ 2-1/2-inch discharges. Pumps rated less than ____ gpm are required to have only ___ 2-1/2-inch discharge. Discharges greater than 2-1/2-inches in diameter may not be located on the pump operator's panel.
>=750 gpm - 2 x 2-1/2 inch discharges
< 750 gpm - 1 x 2-1/2 inch discharge
A minimum of _____-inch pimping, valves, and elbows must be used to supply discharges where 1-1/2, 1-3/4, or 2-inch handlines are attached.
All valves should be designed and maintained so that they are easily operable at pressures of up to ____ psi.
According to NFPA 1901, apparatus equipped with tanks of less than _____ gallons must have a tank fill line of at least __-inch in diameter. Tanks greater than _____ gallons must be provided with at least a __-inch tank fill line.
< 1000 gallons - 1-inch tank fill line
> 1000 gallons - 2-inch tank fill line
The most common type of valve is the ____-____ valve that permits the full flow of water through a line with the minimum friction loss. The most common actuators for ____-____ valves are either ____-____ handles (T-handles) or _______-____ handles. The ____-____ valve handles on some pumpers use a sliding gear tooth rack that engages a sector gear connected to the valve stem.
push-pull handles (T-handles) or quarter-turn handles
____ valves are most commonly operated by a _________. _________ valves are most commonly operated by _______-____ handles.
NFPA 1901 requires that all intake or discharges that are __ inches or greater be equipped with slow acting valve controls. This feature prevents the valve movement from open to close (or vice versa) in less than __ seconds
NFPA 1901 requires some type of pressure control device to be part of any fire apparatus pumping system. This device must operate within ___ to ____ seconds after the discharge pressure rises and restricts the pressure from exceeding ___ psi about the set level.
3 to 10 seconds