Fire Streams (7th Edition)
Chapter 4 Terms
Developing Fire Streams (US)
Coefficient of Discharge
A correction factor relating to the shape of the hydrant discharge outlet, used when computing the flow from a hydrant.
Constant Pressure Relay
A method of establishing a relay water supply using two or more pumpers to supply the attack pumper.
Draft
To draw water from a static source into a pump above the level of the water supply.
Fill Site
The location at which tankers will be loaded during a water shuttle operation.
Jet Siphon
A section of pipe or hard suction hose with a 1 1/2" discharge line inside it to bolster the flow of water through the tube, used between portable tanks to maintain a maximum amount of water in the tank from which water is being drafted.
Nomograph
A special chart based on the Hazen-Williams formula that can be used to assist in the determination of fire flows.
Nurse Tanker
A large water tanker, generally 4,000 gallon or larger, that is stationed at the fire scene and serves as a portable reservoir rather than as a shuttle tanker.
Pitot Tube
An instrument used to measure the total or impact pressure of flowing fluids by converting the velocity energy to pressure energy.
Portable Pump
A small fire pump available in several volume and pressure ratings that can be removed from the apparatus and taken to a water supply inaccessible to the main pumper.
Portable Source
A source of water that can be transported to the location where it is needed and may be a fire department tanker or other vehicle capable of carrying a large quantity of water.
Portable Tank
Any one of several styles of lightweight, easily set up tanks used as a basin from which to draft. Also called a reservoir.
Relay Operation
Using two or more pumpers to move water over a long distance by operating them in series.
Relay Valve
A pressure relief device on the supply side of the pump designed to protect the hose and pump from damaging pressure surges common in relay pumping operations.
Supplemental Pumping
Used when large fires overwhelm the water supply system which involves pumping water from a stronger point in the water system to the units at the fire or pumping it back into the water system where it is weak.
Tanker
A mobile water supply fire apparatus that carries at least 1,500 gallons of water and is used to supply water to fire scenes that lack fire hydrants. Synonymous with Tender.
Tanker Shuttle Operation
An operation where tankers deliver water to a fire scene, generally in a rotating order.
Thread Gauge Device
A device that is screwed onto the discharge of a hydrant to check the conditions of the threads and ensure that they are not damaged.
Unloading Site
The place in the tanker shuttle operation where tankers unload their water into portable tanks.
Waste Line
A hoseline that is tied off or otherwise secured and is used to handle water in excess of that being used during a relay operation.
Water Supply Officer
The officer in charge of all water supplies at the scene of a fire.