Chapter 11

Question 0

Residual pressure

Answer 0

The intake gauge reading when the pumper is discharging water.

Question 1

Static pressure

Answer 1

Pressure on intake gauge when pumper is connected to hydrant but NOT discharging water

Question 2

Difference between static and residual pressure can be used to

Answer 2

Determine how much more water the hydrant can supply

Question 3

Three methods to determine how much water can be supplied from difference between static and residual pressure

Answer 3

Percentage method
First digit method
Squaring the lines method

Question 4

Indicators that the pump is cavitating

Answer 4

Hose streams will pulsate
Pressure gauges will fluctuate
Popping or sputtering sound as water leaves the nozzle
Noisy pump like grave passing through
Lack of reaction on the pressure gauge to changes in throttle

Question 5

Best indicator that the pump is cavitating

Answer 5

Lack or reaction on the pressure gauge to changes in the setting of the throttle

Question 6

Unable to get a reading on the pressure gauge when the pump is in service.
Green light indicating that the pump shift transfer is complete is not illuminated.

Answer 6

Cause: pump drive system is not fully engaged.

Question 7

Unable to get a reading on the pressure gauge when the pump is in service.
Green light is on, no mph reading registers on the speedometer.

Answer 7

Cause:
1.vehicle clutch not engaged

2. Road transmission is not in the proper gear. Automatic transmission selector is in wrong position.

Question 8

Unable to get a reading on the pressure gauge when the pump is in service.
Speedometer reading is normal for pump operation. All indications are correct and rpm reading is as specified.

Answer 8

Causes:
There is no water in the pump

Gauge is defective. Pressure may be there but not reading on the master pressure gauge.

Question 9

Pump will not develop sufficient pressure.
The rpm reading on the tachometer is normal when compared with the up plate.
For two stage pumps

Answer 9

Causes:

• Two stage pump, pump transfer valve is in the wrong position.
• swing check valve may be leaking if the pump is in the SERIES position.
• the transfer valve has not completed its travel and is only partially operated.

Question 10

Pump will not develop sufficient pressure.
The rpm reading on the tachometer is normal when compared with the up plate.
For automatic transmissions

Answer 10

Transmission not staying in pumping gear lockup and is downshifting as load increases.

Wear on the clearance rings inside the pump. May cause excessive slippage.