CH.10 Operating Fire Pumps

Question 1

when is cavitation created?

Answer 1

when air cavities are created in the pump or bubbles pass through the pump

Question 2

what is the benefit of a fout-way hydrant valve

Answer 2

a second pumper can connect and boost pressure and not interrupt the flow of water

Question 3

what is static pressure

Answer 3

pressure on the master intake gauge when connected to a water source but not flowing water

Question 4

what is the general discharge psi for a standpipe (SBC number also)

Answer 4

150psi

Question 5

what is the max lift an engine can do when in good working order?

Answer 5

25’

Question 6

what is the benefit of the reverse lay?

Answer 6

it is the most direct method of supplementing hydrant pressure or doing drafting operations

Question 7

what can happen to the pump if discharge pressure increases too much and the supply can’t keep up

Answer 7

cavitation could occur to the pump and or the supply system

Question 8

what is medium diameter hose?

Answer 8

2.5-3” hose

Question 9

what can occur if dirt or sand is taken into the pump?

Answer 9

it can act as an abrasive and can get into the pump packing and reduce its ability to seal

Question 10

what is the distance the pump should be rated to lift when operating at its capacity

Answer 10

10’

Question 11

what is cavitation?

Answer 11

in theory, water being discharged faster than it is coming into the pump

Question 12

which type of hydrant is the “worst” option to be aware of?

Answer 12

A dead end main hydrant

Question 13

what is the unit of measure for each foot of lift when drafting?

Answer 13

should be 1” mercury for each 1’ of lift

Question 14

what is the best hose lay for a drafting operation?

Answer 14

a reverse lay

Question 15

what is the unit of measurement on the intake gauge when drafting?

Answer 15

inches of mercury (since changes in pressure are so minute)

Question 16

what should be done after nonpotable water is pumped through the apparatus?

Answer 16

the tank should be flushed

Question 17

how much FL is found per floor on a multistory building?

Answer 17

5psi

Question 18

what should be done when attempting to flow from a drafted source?

Answer 18

as the throttle is increased, open the discharge valve slowly (to maintain a prime) until the discharge pressure is achieved.

Question 19

what are 3 ways to reduce pump from overheating when assisting in a relay operation or having to support a long lay

Answer 19

1. establish a continuous minimum flow
2. pull the booster line a distance and flow
3. partially open tank-fill or tank-to-pump valve

Question 20

in a severe case, what noise may be heard in the pump?

Answer 20

sound of gravel passing through the pump

Question 21

what is an easy way to establish prime if the pump primer fails?

Answer 21

open the tank to pump to fill the tank and intake hose (assuming tank to pump valve is able to close)

Question 22

what prevents water from backing from a standpipe at the FDC

Answer 22

clapper valves

Question 23

how is a static water pressure reading obtained when connected to an external water source

Answer 23

when the tank is full and there isn’t any flowing water - read the master intake guage

Question 24

why are dead end main hydrants the “worst” option to be aware of?

Answer 24

there is higher amounts of sediment & deterioration and are served by smaller mains from only one direction

Question 25

what is the procedure when charging a hydrant thats connected to our intake line?

Answer 25

while keeping the intake valve closed, open the drain valve to bleed off air from the charged line

Question 26

how much water is needed to encompass the strainer when attempting to draft

Answer 26

24” in all directions is preferrable

Question 27

what is the typical pressure loss from using a standpipe (SBC number also)

Answer 27

25psi

Question 28

which valve should be closed after establishing an external water source

Answer 28

close the tank-to-pump valve

Question 29

what is the surest indication of cavitation ?

Answer 29

the lack of reaction on the pressure gauge to increase in the throttle

Question 30

what is residual pressure

Answer 30

pressure on the intake gauge when flowing water (connected to a water source)

Question 31

what is a pressure differential?

Answer 31

creating a partial vacuum (via pump primer)

Question 32

when would the transfer valve be placed into parallel (volume) setting?

Answer 32

when supplying a relay operation or master stream (when needing to supply large amounts of water)

Question 33

In general, what can (and ususally does) happen with your supply when your discharge pressure is increased significantly

Answer 33

the supply source may drop due to friction loss

Question 34

what are some signs cavitation is occurring?

Answer 34

1. pressure on the gauge will fluctuate

2. hose streams may pulse

Question 35

how is the vacuum measured on the pump?

Answer 35

it is measured from the surface of the water to the eye of the pump’s impeller

Question 36

at what PSI should your intake pressure never go below when pumping from a pressurized supply source?

Answer 36

<20psi

Question 37

what should you do if the master intake gauge drops below 20psi

Answer 37

either reduce or not INCREASE the throttle to prevent cavitation

Question 38

as far as drafting goes, how much friction loss is lost per 1000’

Answer 38

0.5psi or 1” of mercury

Question 39

to create an effective fire stream, what is the max lift recommended?

Answer 39

20’

Question 40

what is a means of ensuring you dont lose prime when drafting?

Answer 40

use the booster line to flow water back into the static source during the entire draft operation

Question 41

the amount of friction loss in the intake hose depends on…

Answer 41

diameter of the house and the length

longer/smaller hose increases FL