VPR pneumatic valve positioner (referred to as VPR positioner) is Japan Yamatake - Honeywell VFR cam deflection valve dedicated attachment. It is in accordance with the pneumatic regulator signal, the regulator valve quickly and accurately, so as to accurately regulate the valve flow and ensure flow characteristics. I plant the introduction of production in the mid-eighties, has been widely used in petrochemical, power, light industry and chemical industry automation systems. In order to properly use and repair, need to explain its working principle. After the input signal increases, the bellows expands to push the baffle (ie lever) * near the nozzle end face. When the clearance is reduced, the back pressure of the nozzle is increased and the valve core is pushed down by the diaphragm of the relay. The air inlet opens a large exhaust port to close the output pressure increases, so the actuator push rod to move down to make the valve spool open or closed. As the spool rotates, the cam also rotates and the feedback spring is pulled by the cam follower so that the baffle tends to leave the nozzle until the torque generated by the bellows is balanced with the feedback spring moment. As a result of this torque balance, to ensure that the valve opening and input signals corresponding relationship between the accurate, to achieve the correct spool positioning. The following analysis of common causes of failure and measures. Simple exclusions will be omitted. Fault a positioner no output pressure 1. No signal pressure, â‘ pneumatic regulator failure; â‘¡ large number of signal line leak. 2. A large number of bellows leak, repair solder or replacement 3. No gas pressure or gas pressure is too low. 4. Corrugated throttle orifice plugged, using a diameter of less than 0.2mm wire to clear. 5. Locator zero position adjustment is inappropriate, that the gap between the bezel and the nozzle is too large. Use tools to readjust. 6. Cam installation location is wrong. Because a cam contains air-open and air-off, respectively, and other percentages; open air and gas-off linear features, with four mounting holes, easy to install the wrong. 7. Baffle and nozzle end face is not vertical, the baffle and the nozzle face is still in contact after a lot of exhaust. 8. Nozzle hole end face pit, need to be replaced. Burr on the end surface, re-ground. 9. Nozzle and base adhesive leaks. Fault signal decreases, the output pressure is not reduced 1. Zero position adjustment is not appropriate, that is, nozzle baffle clearance is too small. 2. After the relay diaphragm at the throttle aperture is too small or blocked, the use of 0.3mm wire to clear. 3. Bypass mechanism switch position error, the switch should be located in the "ON" position. 4. Deviation spring too hard or wrong choice, supply pressure 0.22MPa spring wire diameter of 1.3mm, 0.28 ~ 0.5MPa when the spring wire diameter of 1.4mm. 5. Cam installation location is wrong. Failure of three gas, no signal, the control valve has been completed most of the trip 1, the relay valve seat and the valve core SR2.3 out of contact or poor seal. 2, in the initial position, baffle and the nozzle face has been in close contact. Failure four basic error (linear) failed 1. Feedback spring force or zero adjustment spring force is not properly adjusted. 2. Cam installation position error or stroke pointer installed wrong. 3. The relay spool and moving valve seat Verlag did not seal. 4. Bellows stiffness is too low, the design requirements of 4.9N / mm. 5. Output pipeline or actuator leakage. 6. Adjustments between the packing compression is too large. Fault five adjustment error between the initial point 1. Cam follower sleeve and the cam is not in contact. 2. Feedback spring selection error, the standard stroke of the spring wire diameter of 0.8mm, split signal is 0.7mm. Failure six locator back to the poor (worse) failed 1. zero position or stroke adjustment is not appropriate. 2. The arm assembly fasteners are loose. 3. After zero position adjustment, tighten the lock screw. 4. Corrugated tube is poor, positive and negative displacement displacement slightly. 5. Cam follower bushing hole and cylindrical coaxiality beyond the design requirements. 6. The relay bias spring poor parallelism between the two ends. 7. Shaft and bush radial or axial clearance is too large. 8. Gas pressure instability. 9. Sleeve and camshaft radial or axial clearance. 10. The feedback spring is not set. More keyword search: Pneumatic valve
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