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Plumbing Terminology
Extensive Online Plumbing Dictionary

Click on any letter of the term you would like to find

F Rating:
A rating of effectiveness of firestop material, measuring its resistance to flames and water.

Face Plate:
Trim piece found behind a single-control wall-mount faucet handle. Also known as a dial plate.

Facultative Bacteria:
Bacteria that can live under aerobic or anaerobic conditions.

THe proper slope or pitch of a pipe for adequate drainage.

A decorative apron or front face. A wooden enclosure holding the main pump assembly for whirlpool and master baths.

An exposed plumbing fitting used as a method of personal expression and to control the flow of water into a basin.

Faucet Drilling:
Number of holes drilled in a fixture to accommodate a faucet and accessories.

Faucet Punching:
Number of holes punched in a stainless steel fixture to accommodate a faucet and accessories.

Faucet Threads:
Special thread size for fittings that connect to faucets.

Faucet Trim:
All of the decorative parts to your faucet.

Fecal Coliform:
The portion of the Coliform bacteria group which is present in the intestinal tracts and feces of warm-blooded animals. A common pollutant in water.

Fecal Material:
Solid waste produced by humans and other animals and discharged from the gastrointestinal tract.

Feed Pump:
A pump that supplies water to a boiler.

Water introduced into a boiler during operation. It includes make-up and return condensate.

Female Fitting:
A fitting that receives a pipe or fitting. A fitting into which another fitting is inserted.

Female IPS:
Female Iron Pipe - Standard internal threads on pipe fittings.

Female Threads:
Faucet threads that are in place on the inside of a fitting.

Material containing or derived from iron.

Metal cover piece for the lavatory overflow opening. Also sometimes used as reference to a brass compression sleeve that seals brass compression fittings to copper tubing.

Female Hose Thread.

Glass in a fibrous form used in the making of products such as shower stalls.

Filter Element:
A device within a filter tank designed to trap suspended solids as water flows through it.

Liquid that has been passed through a filter.

Filtration Rate:
The rate at which the water is traveling through the filter, measure as GPM (gallons per minute) per sq. ft.

Finish Plumbing:
Installation of plumbing fixtures to make the system usable.

Finished Water:
Water that has completed a purification or treatment process.

Female Iron Pipe connection. standard internal threads on pipe fittings.

Fire Hose Closet:
Usually a compartment built into an interior wall, covered by a glass door, holding a coiled fire hose connected to a water line, ready for immediate use in case of fire.

Fire Stand Pipe:
A main water line that feeds a water sprinkling system or fire hose connection. This is separate from the lines feeding restroom or other fixtures.

A variation of vitreous china having greater amounts of quartz and feldspar in the clay material beneath the vitreous surface . Fireclay is heavier (30%), denser, and thicker than regular clay. These properties insure smooth, flat surfaces on large fixtures which is not achievable with standard vitreous china.

Material that fill the opening around penetrating items such as cables, cable trays, conduits, ducts, and pipes and their means of support through the wall or floor to prevent spread of fire.

First Draw:
Water that has been sitting in pipes or plumbing fixtures overnight and is first drawn when taps are opened in the morning. For instance, where lead is present in plumbing, this water would have the highest levels of lead contamination.

First Hour Delivery:
Rating based on the combination of the usable stored volume of hot water in a tank plus the recovery capacity for the first hour of operations.

A broad based term usually referring to faucets, shower valves, and tub fillers. Also refers to various piping parts such as tees and elbows.

Fixed Cone Valve:
A cylinder gate mounted with the axis horizontal. Also known as Howell Bunger valve.

A device that provides a supply of water or its disposal (sink, tub, toilet).

Fixture Unit:
An arbitrary unit assigned to different types of plumbing fixtures, and used to estimate flow rate requirements and drain capacity requirements.

Flame Stability:
Flames on a burner tend to stabilize at a point where flow velocity out and burning back are equal. It changes when primary air or gas rate is adjusted.

A rib or rim for strength, for guiding or for attachment to another object.

Disc-like rubber composite that retains water in the tank. Upon flushing cycle lifts to release water of the tank to the bowl for a complete flushing cycle.

Flapper Valve:
the part on the bottom of the toilet tank that opens to allow water to flow from the tank into the bowl.

Flare Fitting:
A fitting used to connect flex copper pipe, usually gas pipe.

Flaring Tool:
A tool used to create a cone-shaped enlargement at the end of a piece of tubing to accept a flare fitting.

Flex Coupling:
Rubber coupling used to join DWV pipe. Can be used to connect PVC to clay or cast iron above or below ground. Also used for repairs, and attach by used steel band clamps.

Flexible Connector:
A braided hose that connects a faucet or toilet to the water supply stop valve. Serves as a riser but is much more flexible and easier to install. Usually stainless steel or PVC/Polyester reinforced hose.

Float Ball:
The floating ball connected to the ballcock inside the tank that rises or falls with changing water levels in the tank, and actuates or shuts off the ballcock as needed.

Floating Flames:
An undesirable burning operating condition, usually indicating incomplete combustion in which flames leave the burner port to "reach" for combustion air.

A chemical substance that promotes the aggregation or coagulation of suspended particles in the water.

Flood Level Rim:
The top edge of a receptacle from which water overflows.

Floor Drain:
Drainage fitting that sits flush with the floor, used in basements and showers.

Floor Flange:
Cast iron, PVC, abs, or metal ring located flush to floor and is connected to drain pipe which toilet is fastened to.

Floor Sink:
Receptacle usually made of enameled cast iron located at floor level and connected to a trap to receive the discharge from indirect waste and floor drainage. Cleaner and more sanitary than regular floor drains. Usually used in hospitals & restaurants.

Flow Control Valve:
Device designed to reduce water flow to a plumbing fixture. Often used to improve efficiency and reduce operating costs. Also a check valve tat prevents flow reversal wen heater is turned off.

Flow Rate:
Rating in gallons per minutes (GPM) or gallons per hour (GPH).

A passageway for combustion by-products.

Flue Baffle:
A device to deflect, check, or regulate flow through a pipe.

Flue Damper:
A device to minimize heat loss through a venting system.

Flue Exhauster:
A fan installed in the vent pipe which will provide a positive induced draft. Sometimes called a draft inducer.

Flume Spout:
An open spout design that is also referred to as a water fall spout.

Flush Ball:

Flush Bushing:
For whirlpools, a variable valve regulating the amount of water delivered to the jets. For faucets, a valve connector device controlling water flow rate.

Flush Joint:
A connection with both male and female threads cut into the pipe.

Flush Mount Lavatory:
Sink that sits flush and even with the countertop and is supported by a metal ring.

Flush Valve:
Toilet flushing system that uses supply water pressure to compress water to provide a pressurized flush as opposed to gravity flush.

Flushing Surface:
The interior surface of the bowl and all other surfaces which may come into contact with water during flushing.

Toilet valve that automatically shuts off after it meters a certain amount of water flow.

Flushometer Tank System:
Toilet flushing system that uses supply water pressure to compress water to provide a pressurized flush as opposed to a gravity flush.

Flushometer Valve:
The valve located at the bottom of a gravity-operated toilet flush tank, which opens when the trip lever is actuated, and closes when the tank has drained to the desired level. Usually also contains an overflow tube.

Paste applied to copper pipes and fitting before soldering to help the fusion process and prevent oxidation.

Free Mineral Acidity.

Female Pipe Swivel connection.

This refers to the female pipe thread, in which the threads are on the inner side of the connection fitting.

Foam Insulation:
Insulation surrounding the surface of a water heater tank.

Term used to describe a bathtub that is free of walls on all sides.

Foot Valve:
A special type of check valve located at the bottom end of the suction pipe on a pump; it opens when the pump operates to allow water to enter the suction pipe but closes when the pump shuts off to prevent water from flowing out.

The area of floor space taken up by a water heater or other appliance.

A bath enclosure system that mounts all glass or plastic panels in a metal frame.

A bath enclosure system that minimizes the amount of metal used to hold the system panels and door in place.

Term used to describe a bathtub that is free of walls on all sides.

Free Available Chlorine:
The concentration of residual chlorine present as dissolved gas, hypochlorous acid or hypochlorite, not combined with ammonia or in other less readily available form.

The vertical distance between a bed of filter media or ion exchange material and the overflow or collector for backwash water; the height above the bed of granular media available for bed expansion during backwashing; may be expressed either as a linear distance or a percentage of bed depth.

French Drain:
A covered ditch containing a layer of fitting or loose stone or other pervious material.

Water that contains less that 1,000 milligrams per liter of dissolved solids; generally, more than 500mg/l of dissolved solids is undesirable foor drinking and many industrial uses.

Friction Head Difference:
The difference in head required to move a mass of fluid from one position to another at a certain flow rate within a piping system. It is also the specific energy required to overcome friction in the system.

Friction Loss:
The loss of pressure caused by the turbulence created in water while traveling through the pipe.

Frost Line:
The depth to which frost penetrates the earth.

Full Finished:
Refers to tubular products in which the weld has been processed to produce uniform strength and dimensions, and subsequently annealed to obtain proper corrosion resistance.

Full Hydraulic Capacity:
The designed capacity of a pipe or conduit.

Flammable Vapor Ignition.