Chapter 12 Relay Pumping Operations Flashcards
In a relay system which pumper should have the larges pump capacity
The Water Supply Pumper (source)
What sizes fall under the LDH label
3.5” to 6”
How can flow be increased during a relay operation
Placing additional pumpers in the system
Centrifugal pumps are rated at draft to a max capacity of 150 psi what occurs when pressure is raised over 150
The volume capability of the pump is reduced proportinately
Formula to calculate the amount of pumpers needed in a relay
P= (R/D) + 1
P= Pumpers
R= Relay Distance
D= Distance from set numbers ( Based on total flow)
250gpm = 13,200
500gpm = 3300
750gpm= 1450
1000gpm= 825
1250gpm= 525
Relay pumper between source and attack pumper should be waiting for water with __________ and the pump ___________
should be waiting with a discharge or dump line open and the pump OUT of gear
once water has filled the pump and air has exited through discharge the pump can be engaged
As a relay pumper what is advisable to maintain as intake pressure
20 to 30 psi
Order to shut down a relay operation
Start from the fire scene (attack Pumper)
if done from the source, pumpers will run fire pump dry and will cavitate
Slowly decrease throttle
When operating from draft the bleeder valve of the intake used must be…
closed
