Plumbing Dictionary


Plumbing termonalogy.

Browse the glossary using this index

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R

READILY ACCESSIBLE

Having direct access without the need of removing any panel, door or similar covering of the item described, and without requiring the use of portable ladders, chairs, etc.

READY ACCESS

That which enables a fixture, appliance or equipment to be directly reached without requiring the removal or movement of any panel, door or similar obstruction and without the use of a portable ladder, step stool or similar device.

REDUCED PRESSURE PRINCIPLE BACKFLOW PREVENTER

A backflow prevention device consisting of two independently acting check valves, internally force-loaded to a normally closed position and separated by an intermediate chamber (or zone) in which there is an automatic relief means of venting to atmosphere, internally loaded to a normally open position between two tightly closing shutoff valves and with means for testing for tightness of the checks and opening of relief means.

REGISTERED DESIGN PROFESSIONAL

An architect or engineer registered or licensed to practice professional architecture or engineering as defined by the statutory requirements of the professional registration laws of the state in which the project is to be constructed.

REGULATOR

A device for controlling and maintaining a uniform gas supply pressure, either pounds to inches water column (MP Regulator) or inches to inches water column (appliance regulator).

REGULATOR, MP, 2 PSI (13.8 kPa).

A medium pressure regulator which reduces the 2 psi (13.8 kPa) consumers' gas piping pressure to the appliance regulator or to the appliance utilization pressure.

RELIEF OPENING

The opening provided in a draft hood to permit the ready escape to the atmosphere of the flue products from the draft hood in the event of no draft, back draft, or stoppage beyond the draft hood, and to permit air into the draft hood in the event of a strong chimney updraft.

RELIEF VALVE

Pressure relief valve. A pressure-actuated valve held closed by a spring or other means and designed to relieve pressure automatically at the pressure at which such valve is set.

RELIEF VALVE (DEVICE)

A safety valve designed to forestall the development of a dangerous condition by relieving either pressure, temperature, or vacuum in the hot water supply system.

RELIEF VALVE Temperature and pressure.

A combination relief valve designed to function as both a temperature relief and pressure relief valve.

RELIEF VALVE, PRESSURE

An automatic valve which opens and closes a relief vent, depending on whether the pressure is above or below a predetermined value.

RELIEF VALVE, TEMPERATURE

Reseating or self-closing type. An automatic valve which opens and closes a relief vent, depending on whether the temperature is above or below a predetermined value. Temperature relief valve. A temperature-actuated valve designed to discharge automatically at the temperature at which such valve is set.

RELIEF VALVE, VACUUM

An automatic valve which opens and closes a vent for relieving a vacuum within the hot water supply system depending on whether the vacuum is above or below a predetermined value.

RELIEF VENT

A vent whose primary function is to provide circulation of air between drainage and vent systems.

RETURN AIR SYSTEM

An assembly of connected ducts, plenums, fittings, registers, and grilles, through which air from the spaces to be heated or cooled is conducted back to the supply unit. (See also SUPPLY AIR SYSTEM.)

RIM

An unobstructed open edge of a fixture. RISER.  See "Water pipe, riser."

ROOF DRAIN

A drain installed to receive water collecting on the surface of a roof and to discharge such water into a leader or a conductor.

ROOM HEATER

A self-contained gas-burning appliance installed in and for heating rooms. This definition shall not include unit heaters, central heating gas appliances, garage heaters, or vented wall furnaces.

ROUGH-IN

Parts of the plumbing system that are installed prior to the installation of fixtures. This includes drainage, water supply, vent piping and the necessary fixture supports and any fixtures that are built into the structure.