Industrial Process Glossary

304 Stainless Steel (18-8). The most widely used stainless steel grade. Excellent corrosion resistance in most environments. Not suitable for chloride-rich environments (use 316 SS instead). Common in food, chemical, and pharmaceutical applications.

See also: 316 SS, Carbon Steel

316 Stainless Steel. Contains molybdenum for superior resistance to chlorides and pitting corrosion compared to 304 SS. Preferred for marine, offshore, and chloride-containing process environments.

See also: 304 SS, Carbon Steel

A silencer that attenuates noise by converting sound energy to heat through friction in a sound-absorbing fill material (typically fiberglass or mineral wool). Effective across a broad frequency range. Used for air, gas, and steam vents.

See also: Reactive Silencer, Insertion Loss

Actual Cubic Feet per Minute. Gas flow rate at actual operating conditions of pressure and temperature. ACFM = SCFM × (P_std / P_actual) × (T_actual / T_std).

See also: SCFM

American National Standards Institute. Sets dimensional and pressure-temperature rating standards for flanges, valves, and piping components (e.g., ANSI Class 150, 300, 600).

See also: ASME, Flange Rating

American Society of Mechanical Engineers. Publishes codes for pressure vessels (ASME Section VIII), boilers, and piping. ASME-stamped equipment has been designed and tested to meet these codes.

See also: ANSI, Pressure Vessel

The most common material for industrial equipment. Standard carbon steel (A36, A106) is suitable for non-corrosive service at moderate temperatures. Not suitable for corrosive fluids, low-temperature cryogenic service, or sanitary applications.

See also: Stainless Steel, 304 SS, 316 SS

A hazardous location where flammable gases or vapors are present continuously, intermittently, or periodically under normal operating conditions. Requires explosion-proof or intrinsically safe equipment.

See also: Class I Division 2, Hazardous Location

A hazardous location where flammable gases or vapors are handled in closed systems and are present only in case of accidental rupture or abnormal operation. Less stringent than Division 1.

See also: Class I Division 1, Hazardous Location

A filter that causes fine liquid droplets or aerosols suspended in a gas stream to merge (coalesce) into larger droplets that can be drained. Used to remove oil mist, water, and liquid aerosols from compressed air and gas streams.

See also: Separator, Mist Eliminator

Canadian Standards Association. Certifies electrical and mechanical equipment for safety in Canada, including hazardous location ratings equivalent to FM in the US.

See also: FM Approval, Hazardous Location

Decibels A-weighted. A measurement of sound pressure level adjusted to reflect the sensitivity of the human ear. Industrial noise regulations (OSHA) typically set limits at 85–90 dBA for 8-hour exposure.

See also: Noise Attenuation, Insertion Loss

A device that reduces the temperature of superheated steam by injecting a controlled amount of cooling water (attemperating water) directly into the steam flow. Used to condition steam for process use at lower temperatures.

See also: Steam Heater

A jet pump that uses a high-pressure motive fluid (liquid or steam) to entrain and pump a secondary fluid through venturi action — no moving parts. Used for tank mixing, liquid transfer, and vacuum generation.

See also: Jet Pump, Venturi

A bolted pipe connection using raised-face or flat-face flanges with a gasket between them. Allows easy disassembly for maintenance. Rated by ANSI class (150, 300, 600, 900, 1500, 2500) which determines pressure-temperature capability.

See also: Threaded Connection, ANSI, Pressure Rating

A device that generates an electrical signal (open or closed contact) when flow exceeds or falls below a set point. Used for pump protection, process interlocks, and alarms. Paddle-type switches are common for liquids; thermal dispersion for gases.

See also: Flow Rate, Variable Area Meter

Factory Mutual (FM Global) approval. Certifies that equipment has been independently tested and meets FM's standards for safety and performance, particularly for hazardous (classified) locations.

See also: CSA, Hazardous Location, NEC

Gallons Per Minute. Standard unit for liquid flow rate in US industrial applications. 1 GPM = 0.0631 liters/second = 3.785 liters/minute.

See also: Flow Rate, SCFM

An area where flammable gases, vapors, or dusts may be present in sufficient quantities to cause a fire or explosion. Classified by the NEC into Classes (I, II, III), Divisions (1, 2), and Groups (A–G). Equipment must be rated for the specific classification.

See also: FM Approval, CSA, NEC

The reduction in sound power level (in dB) provided by a silencer or noise control device. A silencer with 25 dB insertion loss reduces the sound level by 25 dB at the measurement point.

See also: dBA, Noise Attenuation

A pump that uses the kinetic energy of a high-velocity jet of fluid to entrain and move another fluid. Synonymous with eductor in many applications. Advantages: no moving parts, handles solids, simple maintenance.

See also: Eductor, Venturi

An instrument that provides visual indication of liquid level in a vessel or tank. Types include reflex (single glass, uses light refraction), transparent (dual glass, for colored or opaque fluids), and magnetic (external float with indicator).

See also: Sight Glass, Magnetic Level Gage

A level gage using a magnetic float inside a chamber connected to the vessel. The float's magnet actuates external indicators (flags, reed switches, or transmitters) without direct fluid contact through the glass. Suitable for high-pressure and hazardous fluids.

See also: Level Gage

Maximum Allowable Working Pressure. The highest pressure at which a pressure vessel or component may be continuously operated at a given temperature, as determined by design calculations and code requirements.

See also: Pressure Rating, ASME

A device (mesh pad, vane pack, or cyclone) that removes entrained liquid droplets from a gas stream. Installed in vessels, columns, and separators to prevent liquid carryover.

See also: Coalescing Filter, Separator

National Electrical Code (NFPA 70). The US standard for safe electrical installation. Defines hazardous location classifications (Class I Div 1, Class I Div 2, etc.) used to specify explosion-proof equipment.

See also: Hazardous Location, FM Approval

The reduction of sound energy as it passes through a silencer or travels through a medium. Absorptive silencers attenuate broadband noise; reactive silencers target specific frequency ranges.

See also: Insertion Loss, dBA

National Pipe Taper. The US standard for tapered pipe threads. The taper creates a pressure-tight seal when assembled with thread sealant (PTFE tape or pipe dope). Sizes are nominal (1/4" NPT actual OD is larger than 1/4").

See also: Threaded Connection

The reduction in fluid pressure as it flows through a component (silencer, filter, valve, etc.) due to friction and flow resistance. Expressed in PSI or inches of water column (in. WC). Lower pressure drop means less energy loss.

See also: PSIG, Flow Rate

The maximum allowable working pressure (MAWP) of a component at a specified temperature. Ratings decrease as temperature increases. Always verify the rating at your actual operating temperature.

See also: PSIG, ASME, MAWP

A closed container designed to hold fluids at pressures substantially different from ambient. ASME Section VIII governs design, fabrication, and inspection. Vessels above certain size/pressure thresholds require ASME stamping and a National Board registration number.

See also: ASME, MAWP

Pounds per Square Inch Absolute. Pressure measured from absolute zero (perfect vacuum). PSIA = PSIG + 14.7. Used in thermodynamic calculations and gas flow equations.

See also: PSIG

Pounds per Square Inch Gauge. Pressure measured relative to atmospheric pressure (14.7 PSIA). A system at 100 PSIG has 100 psi above atmospheric pressure. Contrast with PSIA (absolute pressure).

See also: PSIA, Pressure Rating

A silencer that attenuates noise through acoustic reflection and cancellation using chambers, baffles, and tuned passages — no absorptive fill material. Effective at specific frequency ranges. Used for engine exhaust and pulsating flow.

See also: Absorptive Silencer, Insertion Loss

Equipment designed for food, beverage, dairy, or pharmaceutical service where product purity is critical. Features include smooth internal surfaces (Ra ≤ 32 µin), crevice-free welds, and clamp-type (tri-clamp) connections for easy cleaning and sterilization.

See also: 304 SS, 316 SS

Standard Cubic Feet per Minute. Gas flow rate corrected to standard conditions (typically 60°F and 14.696 PSIA). Used to compare gas flows regardless of actual operating pressure and temperature.

See also: ACFM, Flow Rate

A vessel or inline device that separates two or more phases (gas/liquid, liquid/liquid). Centrifugal separators use spinning action; vane-type separators use directional changes to remove liquid from gas streams.

See also: Coalescing Filter, Mist Eliminator

An inline device that allows visual confirmation of flow in a pipeline. May include a rotating impeller or flapper to indicate flow direction and rate. Available in full-view, bull's eye, and drip-type configurations.

See also: Sight Glass

A transparent window installed in a pipe or vessel wall to allow visual observation of the process fluid. Available in flat glass, tubular, and bull's eye styles. Pressure and temperature ratings vary by glass type and frame material.

See also: Sight Flow Indicator, Level Gage

An automatic valve that discharges condensate and non-condensable gases from a steam system while preventing the escape of live steam. Types include float & thermostatic (F&T), inverted bucket, thermodynamic disc, and bimetallic.

See also: Desuperheater

A pipe connection using NPT (National Pipe Taper) threads. Common for smaller pipe sizes (typically 2" and under). Less suitable for high-pressure, high-temperature, or vibration service compared to flanged connections.

See also: Flanged Connection, NPT

A sanitary pipe connection standard (also called sanitary clamp or DIN 32676) using a ferrule, gasket, and clamp band. Allows tool-free disassembly for cleaning. Standard in food, beverage, dairy, and pharmaceutical piping.

See also: Sanitary / Hygienic, Flanged Connection

A flow meter (rotameter) where a float rises in a tapered tube as flow increases, with the float position indicating flow rate. Simple, reliable, no power required. Available for liquids and gases in a wide range of materials and sizes.

See also: Flow Rate, GPM, SCFM

A converging-diverging tube that converts pressure energy to velocity energy and back. Used in eductors, flow meters, and scrubbers. The low-pressure zone at the throat is used to entrain secondary fluids or measure flow.

See also: Eductor, Jet Pump