Pumping Apparatus Driver/Operator (1st Edition)
Chapter 6 Terms
What is Water and Where Does It Come From?

Average Daily Consumption
Average of the total amount of water used each day during a one-year period.

British Thermal Unit (Btu)
Amount of heat energy required to raise the temperature of one pound of water one degree Fahrenheit. One Btu = 1.055 kj.

Circulating Feed
Fire hydrant that receives water from two or more directions.

Cistern
Water storage receptacle that is usually underground and may be supplied by a well or rainwater runoff.

Dead End Hydrant
Fire hydrant that receives water from only one direction.

Dead End Main
Water main that is not looped and in which water can flow in only one direction.

Direct Pumping System
Water supply system supplied directly by a system of pumps rather than elevated storage tanks.

Discharge Velocity
Rate at which water travels from an orifice.

Distribution System
That part of an overall water supply system which receives the water from the pumping station and delivers it throughout the area to be served.

Distribution System
That part of an overall water supply system which receives the water from the pumping station and delivers it throughout the area to be served.

Domestic Consumption
Water consumed from the water supply system by residential and commercial occupancies.

Drain Valve
Valve on a pump discharge that facilitates the removal of pressure from a hoseline after the discharge has been closed.

Dry Barrel Hydrant
Fire hydrant that has its opening valve at the water main rather than in the barrel of the hydrant. When operating properly, there is no water in the barrel of the hydrant when it is not in use. These hydrants are used in areas where freezing could occur.

Elliptical
Describes a large cylindrical, oblong water tank that is used on tankers or tender.

External Water Supply
(1) Any water supply to a fire pump from a source other than the vehicle's own water tank. (2) Any water supply to an aerial device from a source other than the vehicle's own fire pump.

Feed Main
Pipe connecting the sprinkler system riser to the cross mains. The cross mains directly service a number of branch lines on which the sprinklers are installed.

Fire Department Water Supply Officer
Officer in charge of all water supplies at the scene of a fire; duties include placing pumpers at the most advantageous hydrants or other water sources and directing supplementary water supplies, including water shuttles and relay pumping operations. This may also be a permanent, fulltime staff position with responsibility for coordinating, with other local agencies, water supply projects of concern to the fire department.

Gallon
Unit of liquid measure. One U.S. gallon has the volume of 231 cubic inches. One imperial gallon equals 1.201 U.S. gallons.

Gallons Per Minute (gpm)
Unit of volume measurement used in the U.S. fire service for water movement.

Gravity System
Water supply system that relies entirely on the force of gravity to propel the water throughout the system. This type of system is generally used in conjunction with an elevated water storage source.

Gravity Tank
Elevated water storage tank for fire protection and community water service. A water level of 100 feet provides a static pressure head of 43.4 psi minus friction losses in piping when water is flowing.

Grid System Water Mains
Interconnecting system of water mains in a crisscross or rectangular pattern.

Head
Water pressure due to elevation. For every 1-foot increase in elevation, 0.434 psi is gained. Also called Head Pressure.

Hydrant Pressure
Amount of pressure being supplied by a hydrant without assistance.

Hydrant Wrench
Specially designed tool used to open or close a hydrant and to remove hydrant caps.

Hydraulics
(1) Operated, moved, or effected by means of water. (2) Of or relating to water or other liquid in motion. (3) Operated by the resistance offered or the pressure transmitted when a quantity of liquid is forced through a comparatively small orifice or through a tube. (4) Branch of fluid mechanics dealing with the mechanical properties of liquids and the application of these properties in engineering.

Maximum Daily Consumption
Maximum total amount of water used during any 24-hour interval over a 3-year period.

Peak Hourly Consumption
Maximum amount of water used during any hour of a day.

Pounds Per Square Inch (psi)
U.S. unit for measuring pressure. Its metric equivalent is kilopascals.

Pressure
Force per unit area measured in pounds per square inch (psi) or kilopascals (kPa).

Primary Feeder
Large pipes (mains), with relatively widespread spacing, that convey large quantities of water to various points of the system for local distribution to the smaller mains.

Private Connection
Connections to water supplies other than the standard municipal water supply system; may include connection within a large industrial facility, a farm, or a private housing development.

Private Hydrant
Hydrant provided on private property or on private water systems to protect private property. Synonymous Yard Hydrant.

Static Source
Body of water that is not under pressure or in a supply piping system and must be drafted from in order to be used. Sources include ponds, lakes, rivers, wells, and so on.

Triple Hydrant
Fire hydrant having three outlets, usually two 2 1/2-inch outlets and one 4 1/2-inch outlet.

Velocity
Speed; the rate of motion in a given direction. It is measured in feet per second (meters per second), miles per hour (kilometers per hour), and so on.

Wall Hydrant
Hydrant that protrudes through the wall of a building or pump house.

Water Department
Municipal authority responsible for the water supply system in a given community.

Water Distribution System
System designed to supply water for residential, commercial, industrial, and/or fire protection purposes. This water supply is delivered through a network of piping and pressure-developing equipment.

Water Hammer
Force created by the rapid deceleration of water. It generally results from closing a valve or nozzle too quickly.

Water Supply
Any source of water available for use in fire fighting operations.

Water Tower
Aerial device primarily intended for deploying an elevated master stream. Not generally intended for climbing operations.

Waterway
Path through which water flows within a hose or pipe.

Wet Barrel Hydrant
Fire hydrant that has water all the way up to the discharge outlets. The hydrant may have separate valves for each discharge or one valve for all the discharges. This type of hydrant is only used in areas where there is no danger of freezing weather conditions.