Chapter 14 Relay Pumping Flashcards
What are the three options firefighters have when the attack pumper cannot connect directly to a reliable water supply
- used tank water, and allow fire to burn once empty
- water shuttle operation
- water relay operation
When are water shuttle operations commonly used
water supply sources more than 1 mile from incident scene or the department involved has insufficient hose to establish a relay
what makes relay operation superior to water shuttle operations
relay pumping establishes a constant flow of water to the scene, safety, fuel efficiency.
some departments call a two pumper relay
tandem pumping
what and NFPA standard requires pumpers to carry at least 800 feet of 2 1/2 inch or larger supply hose
NFPA 1901
source, or supply, pumper refers to
the pumper connected to the supply at the beginning of the relay operation
relay pumper
sometimes called in-line plumper, pumper in the middle of a relay
attack pumper
the pumper in a relay that is at the scene
hose tenders
may or may not be equipped with the fire pump, usually carry a mile or more large diameter
medium diameter hose
large diameter hose
MDH 2.5”- 3” hose
LDH 3.5”- 12”, ( 3.5”, 4”, 5” are most common)
perhaps the most crucial safety device for relay pumping operations
intake pressure relief valve, also called relay relief valve
what are the two basic types of intake really valves
supplied by pump manufacturer is integrated part of pump intake and add-on relief valves
what should intake relief valves be set at
10 psi above static pressure of the water system
10 psi above the discharge pressure of the previous pump in relay
what are the two basic requirements of a relay operation
- amount of water needed
2. distance between emergency scene and water source
incidents that require flows of less than 500 GPM can probably be…
handled by tank water
where the four options if the relay flow drops below required levels
- increase the size of the hose
- add additional hose lines to the relay
- increase the pump discharge pressure of relay pumpers
- increase the number of pumpers in the relay
what are the NFPA standards for firehose and firehose maintenance
NFPA 1961
NFPA 1962
fire hose should be pumped at pressures that do not exceed ___ of the annual service test pressure
90%
what are the two basic designs for relay pumping operations
maximum distance relay method (more common)
constant pressure relay method
maximum distance relay method
predetermined volume of water, pumpers are spaced appropriately for the maximum distance they can pump that volume, leaving a minimum 20 PSI residual
constant pressure relate method
each pumper in the relay lays out the same type and length of hose, all pumpers pump the same discharge pressure
where the advantages constant pressure relay, over maximum distance relay (5)
- speeds related activation
- requires no calculation
- minimizes radio traffic
- attack pumper can govern fire lines with greater ease
- operators in the relay only have to guide and adjust pressure to one constant figure ( pump one pressure)
when a constant pressure relay is in operation the pump operator should keep correcting their pump discharge pressure to 175 psi until one of the following occurs:
- intake pressure from the pressurized water source drops below 20psi
- adjusting throttle does not result in an increase in RPM
when performing constant pressure relay, how is pressure adjusted
when increasing the relay pressure the first pressure supply proper is adjusted until desired level is reached. then each successive pumper is similarly adjusted…. decreases and pressure start at the attack pumper then starting at the supply pumper again?
what determines the maximum capacity of a relay
the smallest pump and smallest hose line
where should the largest capacity pump be placed in a relay
at the water source, especially if drafting
relay pump operators should try to maintain the pump intake pressure at between ____, if the intake pressure rises above ___ a dump line valve should be opened
20-30psi
50psi
the attack pumper in a relay operation should set their intake relief valve to____
50-75psi
once relay operations are established, the pump operator should take no action as long as intake pressure does not drop below ___ or increase above___. Excessive changes can result in constant varying pressures
10psi
100psi
when shutting down the relay operation start from the____
fire scene to the source
4 reasons why the 175 psi figure may be adjusted during a constant pressure relay pumping operation
- variations in relay pumping spacing
- severe elevation differences
- increased required fire flow
- large diameter hose (requires lower pressure)
