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Selection of pneumatic actuators
by：AIRWOLF
2021-01-15
Pneumatic actuator selection
there are many types of the type of pneumatic actuator, so also be more strict to the requirement of its selection, if improper selection not only affect its working performance, and may not work properly. Pneumatic actuators operating requirements, there are two external determinants: signal and power supply.
VAC signal is usually 120/240 or 12/24 VDC discrete voltage, for electromagnetic valve power supply. If you use the locator control the rotation of the actuator, the signal is usually analog ( 4~20
mA) Or digital signal. Electromagnetic valve or digital locator controls the actuator cylinder air supply and exhaust, alternate the position of the control valve. Electromagnetic valve is used to complete the valve open and close position of the transform. Locator also has the same function, but it is mainly used for adjusting control function, and can support more advanced applications, such as parts of the safety instrument system test. As the cost of digital locator is reduced, its application in sustained growth. Pneumatic actuators of commonly used power is approximately 60 ~ 100
psig compressed air.
each pneumatic actuator after cutting off gas source will have a fault location. Double-acting actuators failure when expired ( Ventilation, ventilation close) , will stop in the location of the valve. But if the pipeline fluid pressure dynamic torque is greater than the friction torque of valve, valve rotation will occur. Spring return type actuator in valve valve will return to the initial position when expired. Such a design is usually choose with failure safety requirements in critical situations.
once the valve torque requirement, can correctly actuator selection. Before the selection, accurate information is required. The client shall provide low gas pressure and movement model of the actuator ( Such as: double acting and spring return type) 。
if required spring return type actuator, failure mode, I. e. , the fault closed or open) Must also be determined. Please follow the following guidelines:
the double use of operation: the choice of actuators in the small gas were calculated using the output torque should be greater than the pressure of the valve torque.
spring reset operation, the fault clearance: the choice of executive mechanism under the condition of small gas supply pressure when spring trip at the end of the output torque should be greater than needed to close the valve torque.
spring reset operation, failure to open: the selected under the condition of small gas supply pressure pneumatic actuator trip end of torque output should be greater than open the valve required torque.
when the valve is or select the gear rack and fork type damper actuators, engineers should pay attention to estimate the valve operating torque and set aside safety margin between the actual output torque of the valve. Under the lack of end user instructions, if you need to add a safety factor to rules and fixed valve torque value, you can follow the following instructions:
security coefficient should be added on the valve torque, rather than on the torque of the actuator.
if you have any advice, or valve end user in the directory specified torque data selection 'torque' or 'selection actuator torque', so no need to add the factor of safety.
if the end user not suggest, or valve catalog data indicates the valve torque, torque to the valve torque with the following safety factor: a.
'valve torque' plus 10%, is used to select as a double acting actuators. b。 'The valve torque' plus 15%, is used to select spring return type actuator.
for safety shutoff valve ( SSOV) And emergency shut off valve ( ESD) Choosing actuators, usually has special performance requirements. If the valve movement frequency less than once a month, it is recommended that the safety coefficient is calculated valve torque multiplied by 2. Most SSOV will shut down in a certain time limit, General soon) 。 If the customer requires a 4 'SSOV automatically shut down, and a second it's very normal. In order to ensure that meet the requirements, the actuator manufacturers should implement the calculation of operating time. Documented calculation is usually required to confirm actuator selection consistency and appropriateness.
most automated valve specifications ( The above four) Manual operation will require, to comply with this requirement, it is very important to specify advanced control actuator accessories. In order to ensure safe and proper operation, the pneumatic actuators must be equipped with pneumatic locking and ventilation ( 值列表) Device. The LOV can empty remaining in the cylinder, may prevent the piston moving air and cause equipment damage. And, more importantly, the device can prevent improper operation, especially in the remote operation, improper operation.
there are many types of the type of pneumatic actuator, so also be more strict to the requirement of its selection, if improper selection not only affect its working performance, and may not work properly. Pneumatic actuators operating requirements, there are two external determinants: signal and power supply.
VAC signal is usually 120/240 or 12/24 VDC discrete voltage, for electromagnetic valve power supply. If you use the locator control the rotation of the actuator, the signal is usually analog ( 4~20
mA) Or digital signal. Electromagnetic valve or digital locator controls the actuator cylinder air supply and exhaust, alternate the position of the control valve. Electromagnetic valve is used to complete the valve open and close position of the transform. Locator also has the same function, but it is mainly used for adjusting control function, and can support more advanced applications, such as parts of the safety instrument system test. As the cost of digital locator is reduced, its application in sustained growth. Pneumatic actuators of commonly used power is approximately 60 ~ 100
psig compressed air.
each pneumatic actuator after cutting off gas source will have a fault location. Double-acting actuators failure when expired ( Ventilation, ventilation close) , will stop in the location of the valve. But if the pipeline fluid pressure dynamic torque is greater than the friction torque of valve, valve rotation will occur. Spring return type actuator in valve valve will return to the initial position when expired. Such a design is usually choose with failure safety requirements in critical situations.
once the valve torque requirement, can correctly actuator selection. Before the selection, accurate information is required. The client shall provide low gas pressure and movement model of the actuator ( Such as: double acting and spring return type) 。
if required spring return type actuator, failure mode, I. e. , the fault closed or open) Must also be determined. Please follow the following guidelines:
the double use of operation: the choice of actuators in the small gas were calculated using the output torque should be greater than the pressure of the valve torque.
spring reset operation, the fault clearance: the choice of executive mechanism under the condition of small gas supply pressure when spring trip at the end of the output torque should be greater than needed to close the valve torque.
spring reset operation, failure to open: the selected under the condition of small gas supply pressure pneumatic actuator trip end of torque output should be greater than open the valve required torque.
when the valve is or select the gear rack and fork type damper actuators, engineers should pay attention to estimate the valve operating torque and set aside safety margin between the actual output torque of the valve. Under the lack of end user instructions, if you need to add a safety factor to rules and fixed valve torque value, you can follow the following instructions:
security coefficient should be added on the valve torque, rather than on the torque of the actuator.
if you have any advice, or valve end user in the directory specified torque data selection 'torque' or 'selection actuator torque', so no need to add the factor of safety.
if the end user not suggest, or valve catalog data indicates the valve torque, torque to the valve torque with the following safety factor: a.
'valve torque' plus 10%, is used to select as a double acting actuators. b。 'The valve torque' plus 15%, is used to select spring return type actuator.
for safety shutoff valve ( SSOV) And emergency shut off valve ( ESD) Choosing actuators, usually has special performance requirements. If the valve movement frequency less than once a month, it is recommended that the safety coefficient is calculated valve torque multiplied by 2. Most SSOV will shut down in a certain time limit, General soon) 。 If the customer requires a 4 'SSOV automatically shut down, and a second it's very normal. In order to ensure that meet the requirements, the actuator manufacturers should implement the calculation of operating time. Documented calculation is usually required to confirm actuator selection consistency and appropriateness.
most automated valve specifications ( The above four) Manual operation will require, to comply with this requirement, it is very important to specify advanced control actuator accessories. In order to ensure safe and proper operation, the pneumatic actuators must be equipped with pneumatic locking and ventilation ( 值列表) Device. The LOV can empty remaining in the cylinder, may prevent the piston moving air and cause equipment damage. And, more importantly, the device can prevent improper operation, especially in the remote operation, improper operation.
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