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ID – Inside Diameter. Diameter measurement from the inside of a pipe. Commonly used for sizing pipe.

IPS – Iron Pipe Size (OD). Same as NPS. Standard pipe threads. Also Internal Pipe Swivel connection (female).

ISO – International\ Organization for Standardization based in Geneva Switzerland. Among the many standards it issues are pump and seal standards for the metric community.

ISO 9000 – A series of five standards for developing a total quality management system. Developed by the International\ Organization for Standardization.

Impeller – Rotating wheel with vanes found inside a centrifugal pump. As it spins at high speed it draws fluids in and thrusts them under pressure to the discharge outlet.

Incomplete Combustion – A product of inadequate ventilation which restricts the flow of air into an appliance. This may lower oxygen content in the surrounding air.

Incoming Inlet Temperature – Temperature of water entering the tank

Indirect Wastes Pipe – Waste pipe used to convey gray water by discharging it into a plumbing fixture such as a floor drain.

Induction Motor – The most common type used in industry. Has a slippage of 2 to 5 percent compared to synchronous motors.

Influent – The stream entering a unit, stream or process, such as the hard water entering an ion exchange water softener.

Injection – The drawing of primary air into a gas burner by means of a flow of fuel gas.

Inlet – An entrance, opening, or aperture for the intake of fluid or gas.

In-line Pump – Small pump which pumps fluid through a line on which it is supported and mounted.

Input – The amount of fuel used by a water heater in a given period of time, usually 1 hr.

Input Rate – The quantity of heat or fuel supplied to an appliance, expressed in volume of heat units per volume of time (BTUs/hour).

Input Rating – The gas burning capacity of an appliance in BTU’s per hour as specified by the manufacturer.

Insanitary – So unclean as to be a likely cause of disease; Contrary to sanitary principles injurious to health.

Inserts – Faucet handles

Insert Fittings – Fittings equipped with external, annular rings fir gripping, which are inserted into flexible rubber or plastic tubing as a connection.

Island Vent – An air admittance valve

Isolation Mount – The four small rubber feet located beneath a whirlpool’s pump base, or attached to the pulse canister assemblies, designed to reduce noise and vibration when the whirlpool is running.

Instantaneous Water Heater – A type of water heater that heats water as it flows through a heat exchanger coil.

Insular – Kohler’s registered trade name for factory-installed insulation, which minimizes condensation on the outside of the tank when exposed to high humidity.

Insuliner – Kohler’s Registered trade name for factory-installed tank insulation, which minimizes condensation on the outside of the tank (also known as tank sweating) when exposed to high humidity.

Integral Stops – Stops that allow the owner to shut off water supply at the faucet for maintenance without shutting off the water supply to the entire house.

Integral Vacuum Breaker – A device typically used in a sink or shower sprayer to keep water from backflowing into the fresh water supply.

Interceptor – Device for separating grease and oil from drainage system. See grease trap.

Isothermal – Action that takes place with no change in temperature.


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Source: “Plumbing Terms” Standard Plumbing Supply. 11 Sept. 2008