1.1 pneumatic control valve main performance and test
Pneumatic control valve performance indicators include: the basic error, hysteresis, dead zone, always point deviation, rated stroke deviation, leakage, sealing, compressive strength, appearance, rated flow coefficient, the inherent flow characteristics, vibration-resistant performance, action life, namely, 13, the former 9 test items for the factory. As the control valve of the transportation, the adjustment of the scope of the work of spring and other factors, pre-installation often requires the performance of the following adjustments to test:
1) basic errors will require the input signal steadily increasing and decreasing according to the direction of input air chamber executive body (or locators), measurement points corresponding to the trip value, and calculate the actual "signal - trip" relationship with the theoretical relations the error between the points. Its maximum value shall be the fundamental error. Pilot sites should include at least the signal range of 0,25%, 50%, 75%, 100%, which is 5 points. The basic error limit of measuring instruments were tested valves should be less than the basic error limit of 1 / 4.
2) The hysteresis testing procedures with the above paragraph 1) above the same. In the same input signal on the measured difference between the positive and negative shall be back to visit the biggest difference.
3) Always-point deviation approach with the first one) point. Signal limit (starting point), Office of the basic error shall be a starting point deviation; signal limit (end) at the end of the basic error of bias.
4) Rated input stroke deviation would be rated by adding pneumatic actuator air chamber (or locators), so that stem way along the road, the actual trip and the difference between nominal and rated travel itinerary of the trip than the deviation shall be rated. Actual travel itinerary must be greater than rated. Y6ZXVN?? P $ _
5) The leakage test medium for 10 ~ 50 ℃ clean gas (air and nitrogen) or liquid (water or kerosene); test pressure of a procedure: When the valve to allow pressure is greater than 350kpa, the test pressure to do according 350kpa , less than 350kpa to do when the press allows pressure; b testing procedures according to the maximum working pressure valve to do. Test signal pressure should ensure that the valve is turned off. In a pilot program, the gas pressure to open valve signal is zero the implementing agencies; gas valve closing pressure of the implementing agencies signals the upper limit of the input signal increases 20kpa; 2-type valve signal pressure should be the executing agency for the design of the specified value. In the b pilot program, the executing agency for the design of the signal pressure should be the specified value. The flow of the fluid under test should be required to join the valve, the valve can be directly exported to connect the export-pass-pass the atmosphere or atmospheric low-pressure head loss measuring device, as identified downstream of the valves and connecting pipes completely filled with dielectric measurements taken only after leaks.
1.2 Electric Control Valve major performance and test
Electric control valve key performance indicators: basic error, hysteresis, dead zone, rated stroke deviation, leakage, sealing, compressive strength, appearance, rated flow coefficient, the inherent flow characteristics and resistance to vibration, temperature, long-term reliability of , explosion-proof, damping characteristics, supply voltage change, ambient temperature change, insulation resistance, insulation strength. Top 10 indicators of the requirements and test methods are the same or similar with the pneumatic valve, in which the fundamental error, hysteresis, dead zone, leakage, sealing, appearance, damping characteristics, supply voltage change, insulation resistance of a pilot project for the factory, after 3 performance requirements and test methods are:
1) The damping characteristics of the damping characteristics of electric control valve, in the positive and negative direction of travel of the two provisions of stem not more than 3 times "half cycle" swing. Test methods were added in the input value of the input signal range of 20%, 50%, 80% signal, observe the stem in the positive, anti-stroke position corresponding to "half-cycle" oscillation frequency.
2) The power supply voltage change electric control valve 220 +20-30 v power supply voltage within the scope changes, changes in the value of stem displacement should not exceed 1.5% of the whole trip. Test method is for the 220v power supply voltage when the input signal range by adding 20% of the value of the signal measurement values corresponding to the valve stem stroke, and then transferred to the supply voltage 190v and 240v, measuring the corresponding change in the value of stem travel . And then followed by adding the value of the signal range of 50%, 80% of the signal, measured changes in the value of stem stroke.
3) Insulation resistance when the ambient temperature is 10 ~ 35 ℃, relative humidity of not more than 85%, the electric control valve insulation resistance shall meet the following requirements: All input terminals of the casing is not less than 20mω; the input terminals of the power supply terminals are not is less than 50mω; power supply terminals on the casing is not less than 50mω. Test method is used 500 megger test.