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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