Pneumatic control valve factory calibration content and method

Pneumatic control valve is mainly a compressed gas source of power, based on cylinder actuators, and pneumatic valve positioner, converters, solenoid pneumatic valve, pneumatic valve, gas storage, gas filters, such as attachments to drive the pneumatic valve, realize the switch quantity or proportion type adjustment. Pneumatic control valve is petroleum, chemical, electric power, metallurgy and other industrial enterprises one of the widely used industrial process control instrument.


calibration of the pneumatic valve pneumatic control before shipment of the main projects are fundamental error, return difference, always deviation, rated travel deviation, leakage, etc.


required for calibration equipment for filtration pressure pneumatic valve, pressure gauge, setter, standard pressure gauges, dial indicator, etc.





pneumatic control principle diagram of the pneumatic valve check table


how to check the pneumatic regulating pneumatic valve basic error, return difference, has some deviation?


1. Basic error


will be stipulated by the input signal is smoothly by direction input actuator (increase/decrease Or locator) , measuring each point of the tour value, calculate the actual 'signal - Stroke 'relationship with the theory of relationship between each point error, the larger values is the fundamental error. Test points should include at least the signal range 0%, 25%, 50%, 75%, 100%, the five points. Basic error measuring instrument should be check pneumatic valve basic error is less than the limit of a quarter.


2. Return difference method with 1 in the same input signal is measured by the positive and negative of larger difference is back to the poor.


3. Always deviation method with 1, the signal of offline basic error is the starting point of deviation, as the fundamental error signal launch of end point deviation.


how to check the pneumatic regulating pneumatic valve rated travel deviation?


add 120% signal to actuator chamber, from 100% 120% signal pneumatic valve stem go trip with deviation (rated rated the ratio of the schedule for the trip Its purpose is to ensure that air breath acting valve to close in place) 。


how to check the pneumatic regulating pneumatic valve leakage?


for 10 - test medium Clean gas 50 ℃ ( Air or nitrogen) Or liquid ( Water or kerosene) 。


test pressure for A program: when the pneumatic valve differential pressure p 350 kpa, without the permission of the test pressure were made to 350 kpa, allow the differential < 350 kpa made to allow differential pressure. B according to the regulation of pneumatic valve, larger work pressure difference. Pressure test signal shall ensure pneumatic valves are closed.
in A program, open air pressure pneumatic valve actuator signals for zero; Breath gas dynamic pressure valve actuator signal as the input signal limit on 20 kpa, two type pneumatic valve actuator signal pressure shall be the design specified value. In application, B actuator signal pressure are design specified value.
test medium flow should be in accordance with the provisions, if the pneumatic valve, pneumatic valve can be directly through the atmosphere or link export atmospheric low head loss measurement device, when confirmation link on the lower reaches of pneumatic valves and pipe filled with medium and then measurable leakage completely.


pneumatic regulating pneumatic valve after finish the above set-up project, and into the next process, and then packing warehousing!