ACCURACY: This is a measurement of a flowmeter’s performance when indicating a correct flowrate value against a “true” value obtained by extensive calibration procedures.

BLOWDOWN: The removal of impurities from the steamwater in a boiler unit. Boiler blowdown is classified as either continuous, with an ongoing removal of impurities together with boiler water from the upper drum, or periodic, with the insoluble contaminants, or sludge, with some boiler water being removed from the lower collectors of the circulation loop no more than once each shift. The heat of the blowdown water can be utilized, but is often wasted.

CHECK VALVES: Check valves are installed in pipeline systems to allow flow in one direction only. They are operated entirely by reaction to the line fluid and, therefore, do not require any external actuation.

DESUPERHEATING: The process by which superheated steam is either restored to its saturated state, or its superheated temperature is reduced.

FLASH STEAM: An effect caused by passing hot condensate from a high-pressure system to a low-pressure system.

HEAT EXCHANGE: Describes all types of equipment where heat transfer is promoted from one fluid to another.

PRV: A Pressure Reducing Valve (PRV) reduces high-pressure steam to a lower required pressure for use, either because of the pressure limitations of the plant, or the temperature limitations of the process.

REPEATABILITY: Describes the ability of a flowmeter to indicate the same value for an identical flowrate on more than one occasion.

SAFETY VALVES: Safety valves are designed to protect the boiler shell from over pressure and subsequent explosion.

SEPARATOR: Separators are designed to remove the moisture that remains suspended in steam flows, which cannot be removed by drainage and steam trapping.

SIGHT GLASS: Provides a method of observing fluid flow in a pipeline.

STEAM TRAP: A device to remove condensate from the steam system while keeping the steam within the system.

STRAINERS: Devices that capture debris in flowing liquids or gases, and protect equipment from their harmful effects, thus reducing downtime and maintenance.

SUPERHEAT: When steam has temperatures higher than saturation where the steam can carry a higher BTU value.

TURNDOWN RATIO: The range of flowrates over which the flowmeter will work within the accuracy and repeatability of the tolerance. Turndown is qualified as Turndown = Maximum flow/Minimum flow.

WATERHAMMER: When a pocket of steam is surrounded by cooler condensate, that steam instantly collapses. The void is then replaced by a rush of condensate, thus creating shock pressure. This is commonly referred to as condensate-reduced waterhammer.

Spirax Sarco (, a manufacturer of steam system products, provided the terms and definitions for this word search.