2019 Pump Manual

Question 1

What are the primary functions of the engine companies

Answer 1

To supply attack lines and devices or to be used as a water supply from a hydrant, or other source to supply the attack engine

Question 2

What are the steps to engage the pumps

Answer 2

1. Shift transmission to neutral
2. Set the parking brake
3. Shift the PTO lever from `road’ to the neutral position, waiting 3 to 5 seconds, and then shifting the PTO lever to pump
4. Press ‘D’ “Drive” on the automatic gear selector
5. Ensure the pump went into gear by observing that the gear selector went to fourth gear; that there are two green lights illuminated at the PTO; and that the speedometer increased to approximately 15 MPH

Question 3

What are the steps to disengage the pumps

Answer 3

1. Utilize the pressure sensing governor at the pump panel to return the speed of the motor to an idle approximately 700 RPM by reducing the discharge pressure and then pressing the “idle” button
2. In the cab of the wagon place the gear selector to neutral
3. Move the PTO from “pump” to “road” stopping on the neutral position for 3 to 5 seconds

Question 4

What is the maximum Engine pressure

Answer 4

300 psi

Question 5

How does the positive displacement pump work

Answer 5

It discharges a definite volume of liquid or gas in each cycle of pump operation, provided that the motive force driving the pump is greater than any resistance offered to the movement of the material being acted upon.

Question 6

How does the impellers of the pump affect the velocity that water is discharged from the pump

Answer 6

Since a rotating impeller with unrestricted discharge imparts velocity to water, the velocity of water leaving the impeller depends upon the revolution per minute (rpm) of the impeller

Question 7

Why does DC fire department use a two-stage pump

Answer 7

The greater need to discharge water at higher pressures as opposed to higher volumes

Question 8

How does the two-stage pump work

Answer 8

Two impellers are mounted on a single shaft so that they rotate in the same direction, at the same speed and at the same time.

Question 9

What are the two rated GPM you’ll find in the dc fire department

Answer 9

Either 1250 or 1500 GPM

Question 10

When is it recommended that you use the transfer valve to maximize efficiency in the pump

Answer 10

When you are discharging volumes at or greater than 70 % of the pumps capacity.

1250 GPM pumps- 880 GPM or greater (70%)
1500 GPM Pump- 1050 GPM or greater (70%)

Question 11

What should you do if it becomes necessary to change from pressure stage to volume or vice versa if pumping is in progress

Answer 11

The pump pressure should be reduced to within 50 psi of the pump intake pressure. This can be determined by standing at the pump panel and subtracting the pressure being displayed by your master intake gauge from your Master Discharge gauge.

Question 12

What is the approximate weight of a cubic foot of water

Answer 12

62.5 pounds

Question 13

Hydrostatics

Answer 13

Is the study of the pressure and equilibrium of liquids

Question 14

Hydrodynamics

Answer 14

Is the study of the motion and action of liquids

Question 15

What are the four factors that the range of a Fire stream are dependent on

Answer 15

Nozzle pressure, nozzle diameter, angle of inclination above the horizontal plane, and wind speed/direction

Nozzle pressure has the most bearing, for its velocity of the water that produces the major variations
Easiest method of increasing the range without changing nozzle diameter would be to create higher nozzle pressure

Question 16

What are the two categories of pumps

Answer 16

Positive displacement- discharges liquid or gas in volume separated by a period of no discharge
Non-positive displacement- a continuous flow

Question 17

What would happen if the discharge outlet of a positive displacement pump were completely closed

Answer 17

Either the driving force would be stalled or something would break

Question 18

Why are centrifugal pumps better for fire service

Answer 18

They can take advantage of higher intake pressures, they can run without pressure relief devices without doing structural damage to the pump, the initial cost is considerably less than comparable pumps

Question 19

How does the pump work in pressure stage

Answer 19

The first impeller receives water from the suction intake. This impeller is responsible for making half the desired discharge pressure. The second impeller is receiving water at half the desired discharge pressure and is responsible for creating the second half of the discharge pressure.

Question 20

Why should the pumps be put in pressure mode when making the pump ready

Answer 20

It offers the most efficient use of the pump on the majority of pumping operations in the District of Columbia.

Question 21

Why and when would the pumps be put in volume stage

Answer 21

It allows for the pump to maximize the volume of water that can be discharged. Maximizing the volume of water is beneficial for operations involving master streams.

Question 22

How does volume stage work

Answer 22

It puts the two impellers in parallel operation. Each impeller is solely responsible for making the desired total discharge pressure.
The impellers are now individually responsible for performing all the work. Each impeller has to generate the total desired discharge pressure.