Safety Valve : A mechanical valve designed to quickly release system over pressure to prevent pressurised systems from exceeding their maximum design pressure. Safety pressure valves or pressure relief valves typically stay closed and will only open when system pressures reach or get close too the maximum pressure setting, at which point the pressure release valve will quickly open. When pressure return back below the safe pressure the safety valve will slowly close.
Schedule : Schedule is a measurement of pipe thickness. The higher the schedule number the thicker the pipe material.
Screw Down Stop Valve : A valve those piston or gate is either lifted from an sealing orifice to allow flow pressed against a sealing orifice to prevent flow through a valve where the gate or piston is attached to a threaded stem. The stem is rotated by an external hand wheel or lever to operate the stop valve.
Screwed Ends : A solenoid valve, gate valve, globe valve or piston control valve whose connecting ends are threaded. Threaded valves are typically female thread (internal thread) and are commonly either BSP or NPT thread. See threads for more information and guidance.
Seals : Seals relates to the sealing materials used through the valve, including the diaphragm, body O Ring. baseplate O ring, stem seals and armature seals used. Typical seals used are NBR, FKM (Viton®), EPDM or PTFE (Teflon®).
Seat : A valve seat is the sealing face inside the valve where the sealing diaphragm, piston or gate will rest and seal against when the valve is closed preventing flow.
Self Relieving : A self relieving valve will vent excess pressure into the downstream or upstream pipeline.
Separator : A separator is a tank or vessel used to separate fluids from gases, sometimes used in crude oil separating systems and air filtration equipment.
Servo Assisted : See pressure assisted. Servo assisted valve means pressure assisted also known as pilot assisted. The pressure difference between the inlet port and outlet port of the valve or pressure differential (Δp), is controlled by a solenoid via an internal servo circuit to move the main sealing piston or diaphragm. In this instance the main sealing piston or diaphragm is not connected to anything and is simply "floating" according to the pressure differences across it.
Shading Ring : A shading ring is either situated on top of the solenoid armature or inside the top of the core tube. Typically shading rings are copper, but can be silver for pure water applications or even Aluminium or Ammonia applications. The function of the shading ring is to act as a stop area of an AC (alternating current) and to act as a mini rectifier.
Shako ™ : Solenoid and pneumatic valve and component manufacturing company in Taiwan. Shako® is also a class 9 registered trade mark number 2456840 for Connexion Developments Ltd.
Shut Off Valve : A shut off valve is an fully Open or fully Closed isolation valve that only has these two positions and cannot be used as a midway or part open or part closed throttling valve. An ideal example of a shut off valve is a solenoid valve with two positions.
Short Pattern Valve : A short pattern valve is a solenoid or other control valve whose length port to port is less than the typical standard.
Silicone Free : Silicone free means that the valve has no trace of silicone either internally or externally. Silicone free valves are used in Paint spraying environments where the presence of any silicone would serious hinder the painting processes.
Silicone Seals : Silicone seals are available with some leading solenoid valve suppliers, it is a soft rubber withstands high temperatures beyond 150 degrees centigrade and low temperatures down to -60 degrees centigrade, but can harden and become brittle when heated with air. Silicone has good resistance to Oil but not diesel, solvents, aniline alcohol, dilute acids or bases, benzene, toluene, gasoline. Silicone has poor resistance to Hot air, steam over 150 C, strong acids and bases and of course Diesel fuel.
Slurry Service : A thick media with solid particles suspended within a fluid. Typical examples would be ceramic slurry, effluent treatment works slurry and coal water slurry.
SNG - Synthetic Natural Gas : Synthetic Natural Gas SNG is a substitute natural gas or synthetic fuel gas that is produced from lignite coal and oil shale fossil fuels or biofuels (bio-SNG) or from renewable electrical energy.
Socket Weld End : A valve or fitting whose end connections have been suitably prepared for socket welding to a pipeline or control valve with the same correctly prepared end fittings.
Sour Gas : Sour gas is a natural gas with a high content of Hydrogen Sulphide (H₂S). Natural gas is considered to be sour if there are more than 5.7 milligrams of H₂S per cubic meter or 4 parts per million by volume.
Solenoid Valve : An electrically actuated electromagnetic control valve for the On/Off open/closed control of liquid or gas media. Solenoid valves offer fast reliable on/off and diverting control for any clean media and are available in brass, bronze, 304 and 316 stainless steel, cast steel, cast iron, ductile iron and various types of synthetic plastic materials to cope with most air, water, gas, liquid, fluid, oil, vacuum, steam, acid or alkali media from cryogenic applications at -200°C to +250°C for pressure ranging from full vacuum up to +500 bar or more, in sizes ranging from M5 up to DN1400 flange.
Specification : Specification of a valve can mean the technical and or physical characteristics of a valve including its function, operation, dimensions, materials of construction, pressure and temperature range, port connection size and type. Alternatively a valve that has been specified will mean the valve make and model has been designed into the system and thus is "specified" and is the only valve that can be installed.
Specific Gravity : Specific gravity the ratio of the weight of fluid compared to the weight of an equal volume of water, or the weight of gas compared to the same volume weight and pressure of air.
Spring Return : Spring return means that there is a mechanical spring within the valve structure that will push the valve back to its default position. For example a spring return normally closed solenoid valve will automatically return to the closed position at rest.
SPU225™ : SPU225® is a pressure assisted 2/2 way stainless steel solenoid valve and is a class 9 registered trade mark number 2456839 for Connexion Developments Ltd.
Stainless Steel : Stainless steel is an iron alloy with a minimum 10.5% of added Chromium and 8% Nickel depending on the grade of stainless steel which prevent the metal from oxidisation in air.
State : The state of a solenoid valve refers to the position of the valve, hence a solenoid valve in the open state is open allowing the flow of media, or closed state preventing the flow of media passing through the valve.
Static Seal : A seal or diaphragm used between two fixed parts that do not move, such as a seal between a valve bonnet and body or solenoid core tube seal. The seal is static and does not move.
Steam : Steam is vaporised hot water which occurs typically at +100°C at normally atmospheric pressure. The higher the pressure the higher the temperature required to boil water to generate steam, adversely the lower the pressure the lower the boiling point of water. The pressure and temperature of steam can be reasonably estimated from the table below. Steam applications require more specialised high temperature rated solenoid control valves typically with PTFE seals and Class H or Class N solenoid coils.
Stem : A stem is a connecting shaft or rod that transmits a mechanical force from a hand wheel, lever or valve actuator into the valve gate or piston to control the valve open and closed positioning.
Stop Off : A procedure to isolate a pipeline in the absence of a shut off valve whereby a collar is temporarily welded onto the pipe and an expandable plug hot tapped (whilst under line pressure) and inserted to shut off the pipeline.
Submersible : A valve or equipment that will be used underwater or sub-sea installation, typically requiring special treatment to resist seawater corrosion and external water pressure. For electrical enclosures and IP ingress protection rating equal or exceeding IP68 is required. See IP ratings.
Surge : A surge pressure is a sudden extreme or excessive rise in pressure within a pipeline caused by emergency pump shut-down or sudden valve closures. Surge pressures can exceed the maximum working and burst pressures of a valve or pipeline which can result in catastrophic failure.
Sweet Gas : Sweet gas is a natural gas with very low or insignificant amounts of Hydrogen Sulphide (H₂S), unlike sour gas that has a high content of Hydrogen Sulphide (H₂S) exceeding 4 PPM volume H₂S.
Swing Check Valve : A swing check valve is a non return or one way valve that allows the flow of media in only one direction. The gate or shut off element is a flap or gate suspended or hung from an over head hinge allowing the gate to swing against or away from a sealing face.