P Trap

See Trap

P & T Relief Valve

Pressure and Temperature Relief Valve - Same as T & P

PB

Polybutylene. A flexible plastic tubing used in water supply systems where allowed by code. Also, polished brass finish on faucets.

PDI

Plumbing and Drainage Institute

PE

Polyethylene plastic material. Also Plain End pipe.

PEX

Cross-linked polyethylene. PEX tubing is commonly used for hydronic radiant floor heat, but increasingly also used for water supply lines. Stronger than PE.

PH

Potential Hydrogen. The hydrogen ion concentration of water to denote acidity or alkalinity, measured on a scale of 0 to 14. Below 7 denotes acidity; above 7 denotes alkalinity.

PHCCA

Plumbing Heating Cooling Contractors Association

P O Plug

Lavatory drain with separate removable plug

PoS

Porcelain on Steel. A finish commonly used on sinks and tubs.

PP

Polypropylene Pipe.

PPM

Parts Per Million. A unit of measure for impurities in water.

PR

Pressure Regulator. Usually required if water pressure ever exceeds 80 PSI on potable water supplies inside a structure.

PSI

Pounds per Square Inch

PSIG

Pounds per Square Inch Gauge.

PVC

Polyvinyl Chloride. A rigid white or cream-colored plastic pipe used in non-pressure systems, such as drainage, waste, and vent systems.

PVD

Physical Vapor Deposition. A modern plating process used mostly with polished brass or gold finishes on faucets. Vaporized zirconium reacts with nitrogen and other gases to form a very durable surface, which will not tarnish or discolor.

Packing

Fibrous material that is used on faucets to prevent leaks.

Packing Nut

The nut that holds the stem of a faucet in position & holds the packing material.

Parallel System

Two or more identical size heaters piped with water connections, that is, cold water travels equal distance into the inlets of the heaters from a "T" connection and hot water travels equal distance from the outlet of the heaters to a "T" connection.

Peak Hour Demand

Time when the largest demand for hot water is needed.

Peak Load Period

The period of the day in which the system has the greatest demand.

Penal Valve

A commercial flush valve, so-named because of its use in penal institutions.

Perfect Vacuum

Theoretically, space without matter in it. A perfect vacuum has never been obtained.

Perforated Pipe

Pipe designed to discharge water through small, multiple, closely spaced orifices or nozzles, placed in a segment of its circumference for irrigation purposes

Petcock

A small faucet for draining liquids or relieving air pressure.

Phase

For ease of production and distribution, A.C. is distributed in what is known as a 3 phase supply using three active wires and one neutral wire.

Phenol

A poisonous and carcinogenic chemical often found in municipal water supplies. Also known as carbolic acid, phenol is a benzene derivative.

Pickling

Pipe immersed into acid bath for removal of scale, oil, dirt, etc.

Piezo Switch

The electronic switch the bather uses to control the whirlpool and optional heater. This switch, based upon the piezo-electric effect, generates a voltage when pressure is applied to it.

Pilot

A small burner used to ignite the main burner.

Pin

External (male) threaded end of pipe.

Pipe Dope

Industry term for pipe-joint compound. Substance applied to threaded fittings to create a watertight seal.

Pitch

Downward slope of a drain pipe in the direction of the water flow.

Plug

Male threaded fitting which seals the end run of a pipe when fitted into a female threaded fitting.

Pivot Door

A shower door that rotates on two metal pivots at the top and bottom of the door.

Plumb

Precisely vertical. Also to test for, or to make vertical. Also to perform plumbing work.

Plumber's Helper

A plunger

Plumber's Putty

Pliable putty used to seal joints between drain pieces and fixture surfaces.

Plumbing Tree

Prefabricated set of drain waste, vent, and supply lines.

Pneumatic

Pertains to devices using compressed air.

Point of Use

Small water heater used for remote locations.

Pop-up Assembly

The drain mechanism of a faucet installed on a lavatory. The drain stopper "pops" up and down.

Pop-up Drain

Type of drain assembly for lavatory and bath. When a lavatory lift rod or bath overflow plate lever is lifted, the pop-up drain closes so the lavatory or tub retains water.

Poppet

Valve that rises perpendicularly to or from its seat.

Porcelain

White ceramic ware that consists of quartz, kaolin, and feldspar. It is fired at high temperature on steel or cast iron to make the surface of some bathtubs, kitchen sinks, and bathroom lavatories.

Porcelain Enamel

Vitreous enamel. Often refers to pressed steel products with a porcelain glaze.

Porosity

A measure of the volume of internal pores, or voids, in ion exchangers and filter media; sometimes expressed as a ratio to the total volume of the medium.

Port

An opening in a burner head through which gas or an air-gas mixture is discharged for ignition.

Positive Displacement Pump

Known as a "PD pump." Gear, sliding vane, progressive cavity, lobe etc. the capacity determined by the pump speed. The maximum head is determined by the horsepower available and the casing strength.

Potable Water

Water that is suitable for drinking.

Potentiometer

An adjustable resistor used to vary the sensing distance of the touch-less faucet.

Powder-Coat

A technique for applying paint to aluminum shower door frames. The aluminum is covered with a powder of dry paint particles and is baked in an oven. This causes the powder to melt and harden into a tough, colorful finish.

Power Venting

Mechanical draft exhaust to outside, usually utilizing room air to support combustion.

Pre-Charged Tank

A water storage tank pre-charged with air at factory featuring a vinyl bag to separate water from air which prevents water-logging. This tank design provides greater draw-down than standard tanks. Pre-charged tanks do not require air volume control.

Pre-Heated Water

Water that has been tempered (heated) for inlet supply.

Pressure Balanced Valve

A shower mixing valve that automatically maintains balance between incoming hot and cold water supplies by immediately regulating fluctuations in pressure. As a result, temperature remains constant, though the outlet pressure may drop. Also called an anti-scald valve

Pressure Head

Pressure in a plumbing system. The unit of measure which is the vertical force exerted by water at a depth of one foot.

Pressure Loss

The term given for the loss of pressure that occurs whenever water moves through a pipe or when water moves uphill against the force of gravity. If the total pressure loss in a piping system exceeds the available static water pressure the water will not flow.

Pressure Reducing Valve

A valve that automatically reduces inlet water pressure to a specified value at its outlet under static cold water conditions.

Pressure Regulator

A device for controlling and maintaining a uniform outlet gas pressure.

Pressure Tank

Device used to pump water from a well.

Pressure Tubing

Tubing used to conduct fluids under pressure or at elevated temperatures or both, and produced to stricter tolerances than pipe.

Primary Air

Air which is mixed with gas before the gas leaves a burner port to burn. Ideal burning condition generally is 10 cubic feet of air per one cubic foot of gas.

Primary Air Inlet

The opening(s) through which primary air is admitted into a burner.

Priming Jet

Opening in bowl through which tank-supplied water flows, designed to propel waste up into the trapway.

Pull-out Spray

Single-control kitchen faucet which offers a retractable hose and spray-head to be used for food preparation and cleaning.

Public Sewer

A common sewer directly controlled by public authority.

Pumping Level

The lowest water level reached during pumping operation.

Purged Line

A plumbing line in which the faucet has been opened and allowed to run for a specified length of time, usually a few minutes