Electric control pneumatic valve selection points and related standards

A pneumatic valve, electric adjustment of product selection points

1. Electric adjustment choose the main control parameters of the pneumatic valve: nominal pressure, nominal diameter, design allowed temperature range, flow coefficient, etc.
　　
　　2. Pneumatic valve sealing performance is one of the main indicators of quality evaluation of pneumatic valve. Pneumatic valve sealing performance mainly includes two aspects, namely, internal leakage and leakage. Internal leakage is refers to the pneumatic valve seat and close to the medium between the degree of sealing. Leakage is refers to the leakage of pneumatic valve stem packing parts, pneumatic valve rod of the gasket leakage and the leakage of pneumatic valve body caused by casting defects. No leakage is allowed.
　　
　　3. Open for traffic and high proportional relationship of rigorous situation, should choose the special pneumatic valve adjustment. High precision adjustment process to choose electric V pneumatic valve adjustment; Diameter > 200 optimizing electric regulating pneumatic valve series.
　　
　　4. The selection of regulating pneumatic valve nominal diameter should be determined according to the pneumatic valve flow capacity. Adjust the pneumatic valve nominal diameter should not be too big or too small. Is too large, increase the engineering cost, and low percentage range, pneumatic valve adjustment precision is reduced, the control performance. Is too small, increase system resistance, can appear even 100% pneumatic valve opens, set the capacity of the system still cannot reach requirements.
　　
　　5. Regulating pneumatic valve ideal flow characteristic are quick opening, parabolic, linear, such as percentage of the four, to choose appropriate flow characteristics according to actual work flow characteristic of regulating pneumatic valve.


note: S = regulating pneumatic valve fully open when the pressure loss/pneumatic valve series branch total pressure loss.

in order to avoid by a pneumatic valve of water flow rate is too high and try to save the water pump power consumption, appropriate makes the working state of pneumatic valve S 0 or less. 7.


2, construction installation points

1. Pneumatic valve installation position, height, import and export direction must comply with the design requirements, the connection should be firmly connected.
　　
　　2. Pneumatic appearance inspection must be conducted before installation of valve, pneumatic valve nameplate should be consistent with existing national standards GB12220 'general pneumatic valve symbol' regulation. For the working pressure is greater than 1. 0 mpa and pneumatic valve with the function of cutting on ZhuGanGuan, should carry on the strength and leak test, qualified rear must use. Other pneumatic valve can not independently test, stay in the system pressure test.
　　
　　3. Pneumatic valves available various forms of end connected to the pipe. One of the main connection mode with screw thread, flange and welding connection. Flange connection, if the temperature exceeds 350 ℃, due to the creep relaxation bolts, flange and gasket, should choose high temperature bolt material.
　　
　　4. Strength test, the test pressure for the nominal pressure of 1. 5 times, duration of not less than 5 min, pneumatic valve shell, packing should be no leakage.
　　
　　5. Leak test, the test pressure for the nominal pressure of 1. 1 times; Test pressure in the duration of the test shall remain the same, with no leakage for qualified for pneumatic valve sealing surface.



three pneumatic valves, electric control the execution of the standard

electric actuators to perform standard:

JB/T8219 - 1999 'industrial process measurement and control system using electric actuators standard'

detection and execute standard

GB/T13927 - 92 'general pneumatic valve pressure test'

JB/T5296 - 91 'general pneumatic valve flow coefficient and flow resistance coefficient test method'

JB/T8528 - 1997 'type pneumatic valve electric device technical conditions'

GB12220 - 89 'general pneumatic valve symbol'

reference standard part of the project

GB50243 - 2002 'ventilation and air conditioning engineering construction quality acceptance specification'

GB50242 - 2002 the building water supply and drainage and heating engineering construction quality acceptance specification'