Fuction and characteristic terms
Spring set range: regulator actuators spring adjusting range to balance the actual process force.
Circulation ability: under specified conditions, the rated flow through valve.
Clearance flow: when intercepting elements without seat, the flow below minimum controlled flow.
Diaphragm pressure range: diaphragm pressure range high and low value difference. This can be considered as a natural or installed characteristics.
Double acting actuators: in arbitrary direction can be supplied power actuators.
Dynamic unbalanced force: because process fluid pressure role, in any provisions of the opening, produced in valve core
Effective area: in film actuators, effective area is effectively produce output force part diaphragm area. The diaphragm effective area may along with its movement and change, usually at the beginning of the trip is the largest, and the end of the trip to a minimum. Molded diaphragm has less effective area change than flat diaphragm, so recommend using molded diaphragm.
Loss of air - closed: such state: when the driver energy is lost, valve closure components moved to the closed position.
Loss of air - open: such state: when the driver energy is lost, valve closure components moved to the opening location.
Loss of air - safety: valve and actuators characteristic: when the driver energy supply disruptions, will allow the valve closure components moved to full-closed, full-open, or stay at last position, any position is considered as protection process necessary. Failure - safe acting mode may need to adopt connected to the actuator auxiliary control.
Flow characteristics: when percentage rated trip changes from 0 to 100%, flows the valve flow and percentage rated stroke relationship. This term should always be expressed as the intrinsic flow feature or install flow characteristics.
Flow coefficient (Cv value) : constants (Cv value) has something to do with valve geometry, for a given trip, can be used to measure the flow capacity. It is American gallon number under the pound pressure drop in per square inch, every minute through valve 60 ° F water.
High pressure restore valve: one type of valve structure, due to streamline internal contour and minimum fluid flow, it will disperse relatively few fluid energy. Therefore, in the valve shrinkage flow cross-section downstream pressure will be restored to the inlet pressure of a high percentage. Straight flow valve, such as rotary valve is typical high pressure restore valve.
Intrinsic diaphragm slice pressure range: When body inner pressure is atmospheric pressure, acting on diaphragm to produce rated core trip pressure high and low value. This range is usually refers to the spring setting value range, because when the valve is setted in the work scope, the range will be valve acting scope.
The intrinsic flow feature: when the pressure drop through the valve is constant, along with the valve from closed position movement to the rated stroke, the relationship between the flow and throttle components travel.
Install diaphragm pressure range: when body under prescribed conditions, acting on diaphragm to produce rated valve core trip pressure high and low value. Due to the force that acting on the throttle components, the inherent diaphragm pressure ranges may be different from installing diaphragm pressure range.
Install flow characteristics: when through valve pressure drop is influenced by changing process conditions, with valve moves from closed position to rated stroke , flow and throttle components relationship.
Low pressure restore valve: one type of valve structure, since the flow passage outline turbulent flow, it will scatter a large part of the fluid energy. As a result, the valve shrinkage flow cross-section downstream pressure will be restored to carry more streamlined channel valve smaller inlet pressure percentage. Although each valve structure is different, but ordinary direct valves are normally have low pressure recovery capacity.
Corrected parabolic flow characteristic: one flow characteristic, which provide equal percentage characteristic in the low travel place of throttle components, and provide linear characteristics in the throttle components of the high travel place.
push down closed structure: a straight-through type valve structure, its throttle component is located between actuators and seat ring, such actuators push-rod launch will move the throttle component to seat ring, and finally close the valve. The term is also used for rotary valve structure. In rotary valve structure, actuators push-rod linear stretch out ball or disc moving towards the closed position. Also known as positive role.
push down open structure: a straight-through type valve structure, its seat ring is located between actuators and throttle component, such actuators push-rod launch will move the throttle component from seat ring, and open the valve. The term is also used for rotary valve structure. In rotary valve structure, actuators push-rod linear stretch out ball or disc moving towards the open position. Also known as reaction.
Adjustable ratio: specifie flow characteristics deviation do not exceed the specified limit, the proportion between the biggest flow coefficient (Cv value) and minimal flow coefficient (Cv value). When flow increases to 00 times minimum can control flow, one is also can easily control valves with a 100:1 adjustable ratio. Adjustable ratio can also be expressed as the largest and smallest control proportion between the flow.
Rated trip: valve throttle components from the closed position moves to rated full open position distance. Rated full open position is the biggest opening recommended by the manufacturer.
Relative flow coefficient: proportion between the specifies trip flow coefficient (Cv value) and rated trip flow coefficient (Cv value).
Seat leakage: when the valve under specified pressure differential and temperature in closed position, through valve flow O
Spring coefficient: spring length per unit changes, spring force changes. In diaphragm actuators regulator, spring coefficient usually use pounds force/inch compression value to represent.
Stem unbalanced force: due to the action of flow pressure, produced forced in any position of stem.
Shrinkage flow section: biggest flow speed, fluid static pressure and sectional area minimum part shunt. In a regulator, shrinkage flow cross-section are usually located in the actual physical limit downstream.
ANSI: the national standards organization abbreviations.
API: American petroleum organization abbreviations.
ASME: American mechanical engineers society abbreviation.
ASTM: American test and material society abbreviations.
Self-control system: a control system can work without human intervention.
Bode graph: a picture of the conversion function in logarithmic baseline logarithm amplitude ratio and phase angle value figure. This is a graphical representation frequency response data most common form
Calibration curve: calibration results graphical representation. One device steady-state output means its steady-state input function. This curve usually express by percentage output range to percentage input range form.
Calibration cycle: Within instrument measuring range, on the direction of rising then drop, using measured variables known value, and record corresponding output numerical calibration cycle curve can be read by increases then reduce device input and obtain. It is usually expressed by percentage output range to percentage input range form. It provides a method of measuring back differential.
Clearance flow: when throttle elements withnot seat closed, the flow lower than the flow can control.
Controller: automatic operation to adjust the controlled variables device.
Enthalpy: a hot dynamic quantity, it is the body's internal energy and its volume and pressure amass sum : H = U + pVo (also called heat capacity).
Entropy: in a thermal dynamic system, cannot transform into mechanical energy theory reactive measure.
Feedback signals: measure directly controlled variables and get feedback signal. For a regulator with locator, feedback signal is usually feedback to the locator throttle components link rod position machinery instructions.
FCI: fluid control organization abbreviations.
Frequency response characteristics: Using amplitude and phase to show steady-state sinusoidal input and caused basic sinusoidal output frequency dependent relationship. The output amplitude and phase shift can be regarded as input test frequency function, and used to describe control device dynamic behavior.
Hardness: metal resistance plastic deformation (usually in the form of depression) capacities. Plastic and rubber resistance pointed piercing its surface ability.
Oscillation: external incentives disappeared, there are still a obvious amplitude vibration. Oscillations are sometimes called circulation or limit cycle. Oscillation is in or close to stable limit place work evidence. In the regulator, control system, or valves locator instability will cause actuators loading pressure fluctuations, oscillation will tend to appear.
ISA: American instrument society abbreviation. Now called international measurement and control institute.
Instrument pressure: supplied by an automatic controller and used to make the output pressure of the valve work.
Loading pressure: used for pneumatic actuators locate pressure. This is the actual effect on actuators diaphragm or piston pressure. If does not use valves locator, load pressure can be instrument pressure.
NACE: used to represent the United States corrosion engineer association. As the organization's scope increasingly internationalized, this noun has been converted into international NACE. NACE is no longer an abbreviations.
0SHA: occupational safety and health law (USA) abbreviations.
The working medium: this refers to fluid, usually for air or gas, used for valves locator and automatic controller work provide motivation.
Work limit: a device can withstand and won't cause working characteristic permanent damage working conditions range.
Scope: the area between the two limits, its spacing can be measured, accepted, or transferred, and use fluctuation range to represent (such as: 3 to 15Psi；—4 to 212°F，—40 to 100℃).
Repeatability: in the whole trip range, along the same direction, under the same working conditions, to the same input values, a series of continuous output measurement value nearly degree. It is often used as an unrepeatable to measure, but expressed in percentage range. It doesn't include back differential.
Sensitivity: after achieving steady state, output amplitude change and caused input change.
Signal: a physical variables, it's one or more parameters carries on the signals represent another variable information.
Signal amplitude sorting (points) : an action process, which there are two or more signal, or two or more terminal control components were driven by an input signal, each terminal control component continuous, with or without overlap respond to input signal amplitude.
Range: fluctuation range value arithmetic differential (such as: scope=0 to 150 ° F, measuring range=150°F, range= 3 to 15Psig, rang= 12 psig).
Air source pressure: a device gas supply port pressure. Commonly used regulator air source pressure value to 3 to 15 Psig spring set range is 20Psig, to 6 to 30 Psig spring setting scope is 35Psig.
Zero error: when input is low range value, a device in the specified application condition error, it is usually expressed as a percentage ideal range.
