Solenoid Valve Terminology L - M

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Solenoid Valve Terminology L

Laminar Flow : The flow of a viscous fluid in which the fluid moves in parallel layers with a fixed velocity gradient from the centre-line to the containing walls of the pipe.

Latching : Latching sometimes referred to as Bi-stable is a solenoid valve that can stay in either open or closed position by means of a semi permanent magnet. A short DC electrical pulse typically up to 50 Milliseconds is applied to energise the magnet which will lift and hold the armature even when no electrical power is supplied. To release the magnetic field or hold a second similar electrical pulse is applied with reverse polarity to neutralise the magnetic hold and release the armature back to its fail safe position.

Leakage Class : Solenoid Control Valves are designed to open, close and divert the flow of media. In most cases the valve will pass small amounts of fluid or gas media over time depending on the application parameters such as pressure, temperature, media etc. Valves can be have a leakage class rating from Class I, II, III, IV, V and VI.

Length : Length or measurements of physical size and normally used to ensure the valve being used will fit into the application. The most common measurement of either a threaded or flanged valve will be the length to determine if the valve will fit into the existing pipework. Length is typically given in millimetres (mm), centimetres (cm) or inches(").

  • 1" inch = 25.4mm
  • 1/16" inch = 1.5875mm
  • 1 foot = 0.305 meters = 12 inches
  • 1 meter = 100 centimetres = 1000 mm
  • 1 cm = 10 mm
  • 1 mile = 1.609 kilometre = 1609 meters/li>

Lever Operated : An operating lever or mechanical arm for the mechanical operation of a process valve, or as a manual over ride for a solenoid valve to manually open or close the valve, manual reset solenoid valve system for a gas safety shut off solenoid valve to prevent auto rest upon electrical power supply.

Life Expectancy : The life expectancy of a solenoid valve depends more on the application rather than the design parameters of the solenoid control valve. Temperature, duty cycle, moving positions, frequency of operation, media cleanliness, voltage tolerances will affect the valve life. Typical valve expectancy will range from 1,000,000 cycles up to 10,000,000 cycles for pneumatic valves>

Lifting Lugs : Lugs or eyelets built into a heavy solenoid or process valve to allow for lifting, transportation and positioning without damaging to the valve body. Typically found on large bore DN300 to DN1000+ solenoid valves, pressure reducing valves, pressure sustaining valves and pressure relief safety valves.

Limit Switch : A volt free electrical switch fitted to a solenoid or process valve that can provide an electrical signal to a remote control or observation control panel to indicate the valve fully open or fully closed position.

Line : A line pipeline or hose through which media will travel, used for the transportation of gases or fluids.

Lip Seal : A "U" shaped round seal as found in a pressure reducing valve, pressure sustaining valve, pilot float valve, pressure relief valve. Offers improved sealing and service life compared to a standard O Ring.

LPI - Liquid Penetration Inspection : A method of detecting surface cracks or imperfections in valve castings and flange welds by means of a coloured dye.

Locking Device : A mechanical device that typically incorporates a padlock to prevent the manual operation or unauthorised actuation of a valve in a process system.

LNG - Liquefied Natural Gas : Natural Gas held as in liquid form under pressure and a cryogenic low temperature, as a liquid the LNG gas requires substantially less volume and can be transported in liquid volume by pipe, lorry, canister or stored to await re-gasification (liquid back to gas).

LPG - Liquid Petroleum Gas : Butane or Propane gas held in liquid form under low pressure, as a liquid the LPG gas requires substantially less volume and can be transported in liquid volume by pipe, lorry, canister or stored to await re gasification (liquid back to gas).

LPG - Liquid Petroleum Gas : Butane or Propane gas held in liquid form under low pressure, as a liquid the LPG gas requires substantially less volume and can be transported in liquid volume by pipe, lorry, canister or stored to await re gasification (liquid back to gas).

Solenoid Terminology M

Male Thread : A male thread is an external thread OD Outside Diameter, ie. threads on the outside. A male thread (OD) will screw into a female thread (ID)

Manifold : A manifold is a system in which a common inlet pipe or media chamber will have multiple outlets. A manifold mount or sub base mount 2/2 or 3/2 way solenoid valve system will have a common inlet with several solenoid controlled outlets.

Material Test Report : A material certificate (3.1b) produced by the steel or stainless steel material manufacturer providing the chemical and mechanical properties of the material within a specific production batch.

Metal to Metal Seal : A metal to metal seat and sealing face within a valve without elastomer or synthetic seal materials. Typically found in special application solenoid valves, aggressive media and corrosion resistant valves, high temperature valves and thick glutinous media valves.

MAOP - Max Allowed Operating Pressure : MAOP or maximum allowed operating pressure or maximum working pressure or actuation pressure of a valve.

Manifold Valve : A manifold or sub base valve is a single shared block with either single inlet with two or more solenoid valves sharing the common inlet and having a solenoid controlled outlet at every station / solenoid.

Manual Over Ride : A manual over ride is a mechanical component attached to a valve such as a lever, Knob, screw or button that allows an engineer or machine operator to "manually" actuate or mechanically "over ride" a valve from its fail safe position. For example a 2/2 way normally closed valve can be manually opened without the need for any electrical supply. This is very helpful for valve commissioning or during power failure situations.

Maximum Operating Voltage : The Max operating voltage that can be applied to the solenoid coil, typically +10% from the stated voltage. For example 24vDC MOV would be 24+10% = 26.4 volts.

Maximum Operating Pressure Differential. (MOPD) : The maximum operating pressure differential is the maximum allowable or design pressure difference ΔP between the inlet and outlet ports when the valve can still function correctly. For example if the MOPD is 10 bar with an inlet pressure of 10 bar and outlet to atmosphere (0 bar) then the pressure difference is 10 bar.

Media : Media refers the the liquid or gas to be controlled such as air, water, steam, oil, acid, alkali, natural gas, ozone, vacuum, sea water, glycol, petrol, diesel, aviation fuel etc.

Media Temperature : Solenoid valve media temperature refers typically to the maximum temperature °C or °F of the liquid or gaseous media being controlled by the solenoid valve. For example a general purpose solenoid valve with an NBR seal may have a maximum design media temperature of+80°C, where as a steam rated solenoid valve would have a maximum media temperature design limit of +185°C.

MGA Controls Operator. : MGA controlled operator is a manually operated gear system for valve actuation, typically by means of a hand wheel.

MGO - Manual Gear Operator : MGO Manual Gear Operator is a manually operated gear system for valve actuation, typically by means of a hand wheel.

Mill Certificate : Certification of chemical analysis and physical properties of a manufactured batch of steel or stainless steel supplied by the steel mill. Mills certifications typically required for the valve shell or pressure containing parts. Mill certs are available from most mills during production offering full traceability but cannot be back dated or supplied at a later date.

Mill Tests : Mill test certification provided from a steel or stainless steel mill or foundry that offer heat, chemical and physical analysis. May on occasion include or be available with impact test reports for the same mill test report.

Minimum Operating Voltage. (MOV) : The Min operating voltage that can be applied to the solenoid coil so that the solenoid valve will still function correctly within is MOPD (Maximum Operating Pressure Differential), typically -10% from the stated voltage. For example 240vAC MOV would be 240-10% = 216 volts.

Minimum Operating Pressure Differential. (MOPD) : Minimum operating pressure differential MOPD is the minimum pressure difference between inlet and outlet ports ΔP required for the valve to function correctly. A valve with a Minimum ΔP of 0.5 bar means that the inlet pressure MUST BE higher than the outlet pressure by at least 0.5 bar or 7 psi for the valve to fully open or close correctly.

MO - Motor Operated : MO or motor operated valve is a ball, gate, globe or butterfly valve who's method of actuation is by means of an electric motor, typically via a reducing gear box.

MOE - Modulus Of Elasticity : Modulus of elasticity is a coefficient of elasticity being the ratio of force (stress) applied against structural deformation (strain).

Mounting Position : The mounting position of a valve relates to the horizontal or vertical position of the controlling mechanism. For example most solenoid valves required mounting vertically, which means that the solenoid coil must be upright or vertical.

MPI - Magnetic Particle Inspection : A test procedure utilising iron filings and a magnetic field to detect imperfections within a metal casting. Imperfections will generate inconsistent or abnormal magnetic fields which are visibility highlighted by the iron filings or particles.

MSS - Manufacturers Standardisation Society : Manufacturers standardisation society is a technical association for the valve and fittings industry who publish written standards and advisory best practices.

MWP - Maximum working Pressure : MWP is the maximum working pressure for a valve typically measured in PSI or BAR. Maximum working pressure can also be given as a Classes, within temperature limits -20ºF to +100ºF.