Chapter 9 - Fire Pump Theory Flashcards
(40 cards)
________ 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.
Piston Pumps
1,000 psi
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 _______.
pressure
speed
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.
150 psi
10 ft
20 ft
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
0.01 inch
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.
500 gpm
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.
500 gpm
1,250 gpm
The maximum capacity of a front mounted pump depends on the limitations of the engine driving it, typically up to _____ gpm.
1,250 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
Rubber Hoses
The piping system and the fire pump itself must be capable of withstanding a hydrostatic test of ____ psi before being placed into service.
500 psi
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
4-inch
Pumps rated greater than _____ gpm capacity may require more than one large intake connection at each location.
1,500 gpm
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.
2-inch
All valves should be designed and maintained so that they are easily operable at pressures of up to ____ psi.
250 psi
