Flashcards in Pump Ops Chpt 12 Deck (34)
Pumper that takes water from a hydrant or static source and pumps it under pressure to the next apparatus in the relay pumping operation water supply should be the apparatus with the largest pumping capacity.
Water supply pumper
Pumpers or pumper connected within the relay that Receive water from the source pumper or another relay pumper, raises the pressure, and then supplies water to the next apparatus.
Pumping apparatus located at the fire scene that receives water form the relay and is responsible for supplying the attack lines and appliances required for fire suppression.
Fire attack pumper
Some for departments, especially that that have on occasion to make many hose lays, employ hose ________ to assist in relay pumping operations.
Hose tenders may be equipped with a fire pump that allows the apparatus to participate in the pumping operation once the supply line is laid. It is possible for a hose tender to carry a mile or more of _______.
Large diameter hose LDH
Pumpers in the relay operation could increase their pump discharge pressure . However this action will not necessarily increase the volume of water through the system. Centrifugal pumps are rated to pump at their at maximum capacity at _______ at draft. When the pumping at pressures higher than _____ psi, the volume capability of the pump is reduced proportionately.
As previously mentioned, fire department pumpers are rated to flow their maximum volume at 150 psi, _______ of their maximum at 200 psi and ____ of their maximum at 250 psi at draft.
Relay distance formula
P= R/D + 1
P total number of pumpers needed
R relay distance
When relaying long distances, the hose lays between each pumper should be as equalized as possible. In cases where multiple diameters of hose are used, the distances between pumpers may be adjusted accordingly. For example, of several pumpers are setting up a relay of 1000 gpm using 5 inch hose, each pumper can be placed _______ apart. If a pumper carrying 3 inch supply hose lays dual supply lines as part of the operation, it's portion of the lay must be ____.
2050 feet apart
900 feet apart
A _______ begins with the largest capacity pumper working from the water source
The relay pumper should be waiting for water with a dump line or discharge open and the pump out of gear. When the source and relay pumpers are ready, the discharge supplying the hoseline on the source pumper is opened while the valve on the ______ is closed in a coordination action.
As water begins to reach each pumper, the driver/operator should _____ any air from the line before opening the intake valve.
For relay pumpers equipped with an adjustable intake relief valve, they should be set to ____ above the static pressure of the water system to which it is attached or _____ above the discharge pressure of the previous pumper in the relay.
When the need for relay pumping has ended, the operation should be discontinued from the _______.
Fire scene first
Driver/operators should refer to NFPA 1962 for further information regarding the placement of relief devices. Sometimes referred to as _______, these appliances are intended to enhance firefighter safety and reduce the possibility of damage to the pump and other water supply components that may be caused by water hammer when valves are operated too quickly or intake pressure rises dramatically.
Relay relief valves
Basically, the need for_______ is determined by the amount of water required at an incident and the distance between the incident scene and the water source
The ______ required will have a major impact on the design of the relay system
Amount of water
The ______ of the relay is the second important consideration
If the amount of flow through a relay operation needs to be increased, depending on the size of the supply hose and fire flow requirements, at least one of the three conditions must be met :
The diameter of the supply hose or the number of hoselines must be increased
The pump discharge pressure of the pumpers involved in the relay must be increased
More pumpers must be added to the relay to overcome friction loss or elevation
Elevation pressure is not affected by the amount of water being moved, only by
The source pumper does not have the _______ at the intake that the relay pumpers receive that aids in preventing pump cavitation
For their own safety and efficient operation of the system, all personnel involved in the relay operation must understand that the overall capacity of the system is determined by the_______
Smallest pump and the smallest diameter of hose in the relay
It is advisable for driver operators to maintain an intake pressure of _____ as a relay pumper
20 to 30 psi
Once the relay operation is flowing water at the desired pressure, the driver operator of the attack pumper should set the _______ at an appropriate level
Attack pumpers equipped with an adjustable intake relief valve should be set between _____ to establish a stable operating condition
50 to 70 psi
The driver operator of the attack pumper should expect small variations in pressure during relay operations. You should not attempt to correct minor fluctuations as long as the intake pressure does not drop below_____
During relay pumping operations, the ______ may be employed to provide an alternate water supply system.
Open relay method
This method consists of deploying portable folding drop tanks at each intake for pumpers in the relay operation
Open relay method
One type supplied by the pump manufacturer is an integral part of the pump intake manifold.
Intake pressure relief valve