Chp 12

Question 1

Relay operation

Answer 1

Using 2 or more pumpers to move water over a long distance by operating them in series

Question 2

Water supply pumper

Answer 2

Takes water from hydrant or static source and pressurizes to next apparatus
Should be biggest pumper
aka Source pumper

Question 3

Relay pumper

Answer 3

Receive water from a pumper and pressurize to the next one

Can be smaller as it can rely on previous pumper

Question 4

Fire attack pumper

Answer 4

At the fire scene

Supplies the attack lines

Question 5

Hose tender

Answer 5

Carries a mile or more of LDH
May also have a pump to help in the relay
Have wide assortment of valves and manifolds

Question 6

LDH is split between attack and supply

Answer 6

Note

Question 7

Relay pumping considerations

Answer 7

Sole source of water or just augmenting?
Length of the lay. If more flow is needed:
Diameter or number of hoses increase
PDP increase (may not fix problem, pumps give best volume at 150 psi, higher reduces volume), also consider hose capacity
More pumpers to overcome FL or elevation
Not practical to replace a line in place; use additional pumpers to create a second line
Can add pumpers to a line to operate at lower pressure

Question 8

Putting a relay into operation

Answer 8

Put largest capacity pump at the source
Source throttles up and opens a discharge till next pumper is ready
Next has discharge open and pump out of gear
Source closes dump line at opens discharge at the same time to avoid losing prime
Bleed air out of dump line before opening intake valve via source pumper then put relay pump in gear
Maintain 20-30 psi residual

Question 9

Operating the relay

Answer 9

Attack pumper sets pressure governor
Set intake relief valve of relay pumpers to 10 psi above static pressure or safe working pressure of hose
Ste attack pumper relief to 50-75 psi
Don’t try to correct for minor fluctuations

Question 10

Shutting down the relay

Answer 10

Start at attack
Decrease throttle, open dump line valve and disengage pump
Mind water hammer

Question 11

Open relay

Answer 11

Use dump tanks at each relay point

Question 12

Relief valve

Answer 12

Either installed by mfg
Or external add on screwed on to the pump intake connection
Need bleeder cuz lots of air can cause loss of discharge pressure or water hammer

Question 13

Inline relay valve

Answer 13

Allows late arriving pumpers to connect into an existing line and boost pressure/volume

Question 14

LDH

Answer 14

Relay supply hose of 3.5” - 6”

Question 15

Minimum pump capacities

Answer 15

Based on table pumping at 185 and 200
750 gpm pump: 250 and 500 gpm flow
1,250 pump: 750 flow
1,500 pump: 1,000 flow
1,750 pump: 1,250 flow

Question 16

Equalize distance between pumpers as much as possible

Answer 16

Different diameter hose may be used but adjust distance and PDP to compensate

Question 17

Overall capacity is determined by the smallest pump

Answer 17

Note

Question 18

Some depts have relay task forces

Answer 18

Note

Question 19

Supply lines used

Answer 19

If MDH of 2.5” or 3” lay multiple lines

If LDH of 4” or 5” usually just one line

Question 20

Pushing air into the pump may cause water hammer

Answer 20

Note

Question 21

Remember to close bleeder valve when drafting

Answer 21

Note

Question 22

Late arriving pumpers

Answer 22

Initial line can be small and spaced apart
Inline relay valve is placed on supply
Late pumpers connect to it and boost pressure and volume

Question 23

If supplying more than one attack pumper

Answer 23

Use a discharge manifold to break LDH into 2 or more lines to connect to different pumpers
Have one LKH inlet and a combo of MDH and LDH discharges

Question 24

Relay relief valve

Answer 24

Placed along line to enhance safety and reduce possible damage to the pump

Question 25

Pump efficiency

Answer 25

100% of capacity at 150 psi
70% at 200 psi
50% at 250 psi
at draft

Question 26

If pressure governor

Answer 26

Attack pumper sets it to pressure to correct for cumulative pressure fluctuations along the line