Domestic Pneumatic Control Valve Leakage Reasons and Solutions

Pneumatic control valve with its high precision control, easy installation and commissioning advantages in a variety of industrial control systems have been more widely used. However, in the process of using, there are also some problems plaguing the on-site instrumentation personnel, which is the valve leakage problem. Here we explore the reasons for the common leakage of pneumatic control valves and solutions, hoping to help the factory site maintenance personnel a little help. 1, the implementing agencies zero set inaccurate, did not reach the valve all-bit. Adjustment methods: 1) manually shut off the valve (must be confirmed that has been completely closed); 2) re-manual closing of the valve, with a little effort to screw; 3) 4) and then adjust the limit 2, the valve is pushed down to close the type, the thrust of the implementing agencies is not big enough, in the absence of pressure when the debugging is easy to reach the full turn, and the next push, you can not overcome the liquid upward thrust , So off is not in place. The solution: replace the thrust of the implementing agencies, or the balance of spool to reduce the media unbalanced force. 3, Pneumatic valve manufacturing quality caused by the internal leakage Valve manufacturers in the production process on the valve material, processing technology, assembly process, lax control, resulting in seal surface grinding failed, pitting, trachoma and other defects of the product is not completely Eliminated, resulting in pneumatic valve leakage. Solution: Rework the sealing surface. 4, the pneumatic control valve control part of the internal leakage affect the valve Pneumatic control valve is the traditional control valve limit switches, torque switches and other mechanical control methods, as these control elements affected by the ambient temperature, pressure, humidity, Resulting in misalignment of the valve, spring fatigue, coefficient of thermal expansion and other objective factors, resulting in leakage of pneumatic control valve. Solution: readjust the limit. 5, pneumatic control valve debugging problems caused by the internal leakage by the processing, assembly process, the pneumatic control valve generally exists after the manual shut off the pneumatic can not open the phenomenon, such as the action by the upper and lower limit switch position of the pneumatic control valve stroke Adjust the smaller number, then the pneumatic control valve lax or the valve does not open the exhibition does not unfavorable state; to adjust the stroke of the pneumatic valve larger, then caused by the torque switch protection action; if the action torque value of the switch to adjust Larger, then there crash crash gear or crashed the valve, and even the motor burned accident. In order to solve this problem, usually, the pneumatic control valve manually adjust the pneumatic control valve to the end, and then to open the direction of a lap, set the pneumatic limit valve lower limit switch position, and then open the pneumatic control valve to the full set limit Switch position, so that pneumatic control valve will not appear after the manual shut off the pneumatic open the phenomenon, in order to make the pneumatic door open, close freely, but in fact caused the pneumatic door leakage. Even if the adjustment of the pneumatic control valve is ideal, the position of the limit switch is relatively fixed. The media controlled by the valve continuously scrubs and wears away the valve during operation, and may also cause internal leakage caused by the valve being closed tightly. Solution: readjust the limit. 6, the selection error caused by the cavitation erosion of the valve caused by pneumatic valve cavitation cavitation and pressure-related, when the actual pressure difference â–³ P valve is greater than the critical pressure to produce cavitation â–³ Pc, to produce cavitation, empty During the process of bubble burst, huge energy is released, which has a great damaging effect on throttling components such as the valve seat and the valve core. Normally, the valve can be operated under cavitation for a maximum of three months or even less, ie, the valve is subjected to Serious cavitation corrosion, resulting in high seat leakage up to 30% of rated flow above, which is irreparable, therefore, different purposes of the pneumatic door has different specific technical requirements, according to the system to choose a reasonable process Pneumatic control valve is crucial. The solution: process improvement, use multi-stage buck or sleeve valve. 7, the media flushing, pneumatic control valve aging caused by leakage within the pneumatic control valve adjusted after a certain period of operation, due to cavitation and valve erosion, valve core and seat wear, internal components aging and other reasons , There will be a large pneumatic regulator valve stroke, the pneumatic control valve is not strict off the phenomenon, resulting in greater leakage of pneumatic control valve, with the passage of time, the phenomenon of pneumatic valve leakage will be more serious. The solution: readjust the actuator, and regular maintenance, calibration can be.

Oxygen Sensor

Automobile oxygen sensor is a key feedback sensor in the control system of electric injection engine. It is also a key part to control automobile exhaust emission, reduce automobile pollution to environment and improve the quality of automobile engine fuel combustion. The oxygen sensor is installed on the engine exhaust pipe.

Application: Cars

Q: How do I know the O2 sensor is good or not?
A: The only way to know if the O2 sensor is functioning normally is to check its responsiveness to changes in the air/fuel mixture, by Voltage Measurement or Waveform Simulation.
Use a 10-megaohm digital voltmeter. Hook up the voltmeter's red probe to the sensor's signal wire and the black probe to engine ground. (Use back probe method, DO NOT pierce the wire.) For a good sensor, voltage should fluctuate constantly between 0.1 and 0.9 volts after starting the engine for 2 or 3 minutes.

control system of electric injection engine, oxygen sensor, O2 sensor

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