IFSTA 9 Fire Pump Theory Flashcards
(100 cards)
Define positive displacement pump
Self priming pump that utilizes a piston or interlocking rotors to move a given amount of fluid through the pump chamber with each stroke of a piston or rotation of the rotors
Which type of pump is referred to as a “constant flow machine”
Positive displacement pumps
What are three characteristics of positive displacement pumps
pg 295
Self priming
deliver a definite volume of water or air
exhaust air from pump deliver water
define piston pump
pg 296
Type of positive displacement pump using one or more reciprocating pistons to force water from the pump chambers
define rotary pumps
page 296
Simplest of all fire pumps small capacity low volume high-pressure or priming driven by electric motor or clutch
What are two types of rotary pumps
page 296
rotary gear
rotary vane
define rotary gear pump
page 296
two gears rotating a tightly messed pattern inside a water tight case
amount of water pumped depends on size of the pockets in the gears and speed rotation
define rotary vane pump
page 298
positive displacement pump using hydraulic systems a rotor with attached veins is mounted off center inside a pump housing pressure is imported on the water as a space between the rotor and pomp housing wall decreases. shelf adjusts with wear
most common type used in centrifugal fire pump primers

define centrifugal pump
page 298
non-positive displacement Pump with one or more impellers that rotate and utilize the centrifugal force to move water most modern pumps are this type
define impeller
page 299
Vained circulating member of the centripical pump that acts as the disc receiving water through the eye in a center transmits motion to water resulting in velocity
It’s speed determines the extent to which water may overcome the force of gravity
define volute
page 299
spiral divergent chamber which receives velocity energy of the water by the impeller and converts it to pressure
what three factors influences a centrival fire pumps discharge pressure
page 300
Amount of water being discharged
speed at which the impeller is turning
pressure of water when it enters a pump from a pressurize source (hydrant relay etc.)
define single stage centrifugal pump
page 300
Single impeller
maybe; front mount, PTO, auxiliary or midship
Flow capacity up to 2250 GPM
define multistage centrifugal pump
page 301
A pump with an impeller for each stage mounted in a single housing impeller is may be a denticle the same capacity on a single shaft capable of connecting and series or in parallel
define pumping in parallel
(volume position)
page 301
Total amount of water the pump can deliver is equal to the sum of all the impellers operating in stages together
Define pumping and series
(pressure position)
page 302
when transfer valve is set in pressure position all water from intake manifold is directed into the eye of the first impeller, The second impellar further increase pressure in delivers water a higher pressure into the discharge port
At what percent range is the first impeller increase pressure a discharge when pumping and series
page 302
50-70%
if there’s any doubt as to whether or not to operate and pressure or volume which should a driver operator choose
page 303
Volume (parallel mode)
the pump will be cable supplying 100% but really capacity at 150 psi at 10 feet of lift with 20 feet of suction hose while drafting
Power operated transfer valves may operate at pressures has high as what?
page 303
200 psi
The opening between the pump casing in the hub of the impeller is usually limited to what?
page 304
.01”, Any increase lessons the effectiveness of the pump
define wear rings
page 304
replaceable rings are attached to the impeller indoor pump casing to allow us all running clearance between impeller and pump casing without causing wear of either
to maintain the preferred spacing instead of replacing the entire pump
Which type of seal is the most common type used today to prevent air leaks between the shaft and the pump casing Because it requires no adjustment but does require operation of the pump regularly
page 306
Mechanical seals
what is the most common type of seal packing material?
page 306
Rope fibers impregnated with graphite or lead
what are packing rings
page 306
Primarily use on older fire pumps they wear with the operation of the shaft and can be tightened to address leaks