Fire Hydrants and Valves Flashcards

A comprehensive set of 150 vocabulary flashcards covering the installation, types, parts, classification, and operation of fire hydrants and water distribution valves, as well as backflow prevention methods.

Cross-Connection

Any connection or structural arrangement between a potable water system and another fluid system through which backflow can occur.

Backflow

The flow of any substance (liquid, gas, or solid) back into a potable water system.

Backpressure

A condition occurring when a cross-connected system is at a higher pressure than the potable water system.

Backpressure Example

A chemical storage tank pressurized to a level greater than the water system it is connected to.

Backsiphonage

The condition where foreign material is drawn into the water system because the system pressure is less than atmospheric pressure.

Backsiphonage Occurrence

Can occur any time the distribution system is depressurized.

Building Spacing (Hydrants)

Guideline stating there must be sufficient space between a fire hydrant and the building it is protecting.

Hydrant Location Selection

Guidelines recommend fire hydrants be located near street intersections.

Hydrant Street Setback

Hydrants should be located back from the street to avoid vehicle contact.

Hydrant Pumper Access

Hydrants must be close enough to the street for a pumper connection while the vehicle is on the pavement.

Hydrant Snow Protection

Hydrants should be located such that they won’t be covered by plowed snow.

Distance Off Curb

Fire hydrants should be placed $2\,feet$ off the curb.

Minimum Main Diameter

Fire hydrants must be fed by a minimum main diameter of $6\,inches$.

Auxiliary Valve Placement

Should be installed between the fire hydrant and the main line.

Breakaway Flange Placement

Should be installed $2\,inches$ above the ground surface.

Dry-Barrel Hydrants

Hydrants used in locations where temperatures drop below freezing.

Dry-Barrel Main Valve

The main valve is located below ground level to prevent freezing.

Dry-Barrel Drain Valve

Allows water to drain from the barrel when the main valve is closed.

Wet-Barrel Hydrants

Hydrants that are filled with water at all times.

Wet-Barrel Climate Suitability

Not used in locations that experience freezing temperatures.

Wet-Barrel Valve Configuration

Includes a separate valve for each outlet nozzle.

Wet-Barrel Impact Result

A geyser results when this hydrant type is hit and damaged because there is no main valve.

Warm-Climate Hydrant Valve

The main valve is located at ground level.

Warm-Climate Flow Control

The main valve controls the flow from all nozzles simultaneously.

Warm-Climate Barrel Mechanism

Has no drain mechanism in the upper barrel and the lower barrel remains pressurized.

Flush Hydrants

Used where above-ground hydrants would be objectionable, such as airport taxi-ways or pedestrian malls.

Flush Hydrant Depth

Designed to be completely below ground level.

Flush Hydrant Access

Accessible through a cover.

Flush Hydrant Internal Design

Utilizes a dry-barrel design.

Upper Section (Hydrant)

Commonly referred to as the nozzle section or the head.

Operating Nut Shape

Usually five sided to require a special wrench for operation.

Bonnet

The upper most section of the fire hydrant barrel.

Upper Barrel Function

The portion above ground that carries water to the nozzles.

Outlet Nozzle Connection Sizes

Commonly sized at $2\,1/2$ or $4\,1/2\,inches$.

Small Nozzle Connections

Used for connecting hoses directly to the fire hydrant.

Large Nozzle Connections

Used for connecting a pumper suction hose to the hydrant.

Nozzle Caps

Used to protect the nozzle threads from damage.

Lower Section Composition

Consists of the lower barrel, the main valve, and the base.

Lower Section Height

Mostly buried but extends approximately $2\,inches$ above ground level to connect to the upper barrel.

Main Valve Assembly

Includes the operating stem and a resilient valve gasket.

Shoe

Another name for the base of the hydrant; also called the inlet, elbow, or foot piece.

Hydrant Base Material

Usually constructed from cast iron.

Auxiliary Valve Purpose

Installed near a hydrant to allow it to be isolated for maintenance or repair.

National Fire Protection Association (NFPA)

Organization that recommends practices for testing, classification, and marking of fire hydrants.

Minimum Residual Pressure

The NFPA recommends a minimum of $20\,psi$ residual pressure during fire flow.

Class AA Hydrant

Flow capacity of $\ge 1500\,gpm$.

Class AA Color

Marked with a Blue color on the bonnet and nozzle caps.

Class A Hydrant

Flow capacity between $1000$ and $1499\,gpm$.

Class A Color

Marked with a Green color on the bonnet and nozzle caps.

Class B Hydrant

Flow capacity between $500$ and $999\,gpm$.

Class B Color

Marked with an Orange color on the bonnet and nozzle caps.

Class C Hydrant

Flow capacity of $< 500\,gpm$.

Class C Color

Marked with a Red color on the bonnet and nozzle caps.

Gate Valve

The most commonly used valve in water distribution systems.

Gate Valve Primary Purpose

Designed exclusively to start or stop flow.

Gate Valve Throttling

Gate valves are not intended to be used to throttle flow.

Gate Valve Mechanism

The disc is raised into the bonnet to open.

Gate Valve Head Loss

Characterized by minimal head loss when in the full open position.

Large Gate Valve Accessories

Equipped with equalizing lines or bypass valves for use prior to opening.

Rising Stem Valve

A type of gate valve also known as Outside Screw and Yoke (O.S. & Y.).

Non-rising Stem Valve

A gate valve where the stem does not move upward when the valve is opened.

Tapping Valves

Specialized gate valves used for making new connections to existing mains.

Globe Valve Typical Use

Standard household water faucets are typically this valve type.

Globe Valve Main Suitability

Not well suited for distribution system mains due to significant head loss.

Globe Valve Throttling

Can be used to throttle flow and control downstream pressure.

Needle Valve Design

Similar to globe valves but with a long tapered metal shaft and a tapered seat.

Needle Valve Flow Area

Allows slight changes in the allowable flow area as the valve is opened.

Needle Valve Primary Application

Used for precise throttling applications like hydraulic valve actuator lines.

Pressure-Relief Valve Mechanism

The disc is held against the seat by adjustable spring pressure.

Pressure-Relief Valve Function

Opens when system pressure exceeds set spring tension and closes once pressure is reduced.

Diaphragm Valve Operation

A variation of the globe valve where system pressure exerts force on a diaphragm to assist in closing.

Altitude Valve

The most commonly used type of diaphragm valve in water systems.

Pinch Valve

Operated by pinching shut a flexible interior liner.

Pinch Valve Limitations

Limited in use and only available in relatively small sizes.

Pinch Valve Application

Used for throttling corrosive liquids or liquids that might clog other valves.

Rotary Valves

A category of valves including plug valves and ball valves.

Rotary Valve Operation Speed

Only requires a $1/4$ turn to move from fully open to fully closed.

Curb Stops

Small plug valves used for service connection isolation.

Corporation Stops

Small plug valves used at the water main connection point.

Large Plug Valve Application

Used in high pressure applications such as high-lift pump discharges.

Plug Valve Throttling

Can be used to throttle flow without causing damage to the valve.

Ball Valve

Similar to a plug valve but uses a sphere as the seating element.

Butterfly Valve Mechanism

Has a disc that rotates on a shaft within the valve body.

Butterfly Valve Full Open State

The disc is parallel to the axis of the pipe with water flowing on both sides.

Butterfly Valve Head Loss

Higher head loss than a gate valve, but easier to open against pressure.

Butterfly Valve Throttling

May be used for throttling under conditions of low flow and pressure.

Check Valve

Valve designed to only allow flow in one direction.

Check Valve Pump Application

Commonly used to prevent backflow through idle pumps.

Foot Valve

A type of check valve used to maintain prime on centrifugal pumps by keeping the casing full.

Water Hammer Cause

Can be caused in a distribution system by the sudden closing of a check valve.

Cushion Swing Check Valve

A special check valve used to minimize hydraulic shock to the system.

Counterweights (Check Valves)

Used to slow the closing of a check valve to minimize hydraulic transients.

Manual Operation (Exposed)

Valves usually operated with hand-wheels.

Manual Operation (Buried)

Valves usually have a $2\,inch$ square operating nut used with a special operator tool.

Electric Valve Operation

Uses small motors and a gear box to rotate the valve stem.

Electric Limit Switches

Used to turn off a motor once the valve reaches the fully open or fully closed position.

Hydraulic Valve Operation

Commonly found in water treatment plants and pumping stations using water or fluid pressure.

Solenoid Valves

Used in hydraulic systems to direct fluid to operating cylinders.

Pneumatic Valve Operation

Operates similarly to hydraulic actuators but uses compressed air as the force.

Pneumatic Reserve Requirement

Requires sufficient reserve air capacity to allow operation during power failures.