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A–B–C–D–E–F–G–H–I–J–K–L–M–N–O–P–Q–R–S–T–U–V–W–X–Y QEV (Quick Exhaust Valve) A one-way valve connected directly to the actuator cylinder. Having a large exhaust port, it allows fast dumping of air from the cylinder directly to atmosphere. Qualification Test Additional testing requirements are performed on a product to determine whether or not the product conforms to all of the requirements of … Read more

A–B–C–D–E–F–G–H–I–J–K–L–M–N–O–P–Q–R–S–T–U–V–W–X–Y Potentiometer The principle of its operation is that a voltage gradient is generated across a resistive element which has a variable pick off point connected to the valve stem. As the stem moves, the voltage changes across the potentiometer to provide an electrical output of the valve position. Power Operator Powered valve operators are … Read more

A–B–C–D–E–F–G–H–I–J–K–L–M–N–O–P–Q–R–S–T–U–V–W–X–Y OD (Outside Diameter) The measurement of the outermost diameter of a circular part. Operator A device which converts manual, hydraulic, pneumatic or electrical energy into mechanical motion to open and close a valve. Also called a Valve Actuator. O-Ring An elastomeric or synthetic seal ring of circular cross section. Operating Temperature A media temperature … Read more

A–B–C–D–E–F–G–H–I–J–K–L–M–N–O–P–Q–R–S–T–U–V–W–X–Y NACE International A professional organization for the corrosion control industry established in 1943 which publishes papers articles and standards on all aspects of corrosion and has written the definitive standard for valve materials for sour gas service. Formerly known as the National Association of Corrosion Engineers. www.nace.org National Pipe Thread A US standard for … Read more

A–B–C–D–E–F–G–H–I–J–K–L–M–N–O–P–Q–R–S–T–U–V–W–X–Y M.A.S.T. (Maximum Allowable Stem Torque) A torque value published by the valve manufacturer of the maximum torque that may be applied to a valve stem before permanent deformation may occur. The actuator maximum torque must not exceed this figure. Magnetic Particle Test An inspection procedure for detecting surface cracks and other discontinuities at or … Read more

A–B–C–D–E–F–G–H–I–J–K–L–M–N–O–P–Q–R–S–T–U–V–W–X–Y Laminar Flow The flow of a viscous fluid in which the fluid moves in parallel layers with a fixed velocity gradient from the centerline to the containing walls of the conduit. Sometimes referred to as Streamline Flow. Leak Rate Rate at which a fluid (liquid or gas) passes a seal or barrier. Lifting Lugs … Read more