(1) The conditioning valve does not operate. The symptoms and causes are as follows:
1. No signal, no air source. (1) The air source is not opened, (2) because the water contained in the air source freezes in winter, resulting in the blockage of the air duct or the blockage of the filter and pressure reducing valve, (3) the compressor is faulty; (4) Leakage of air source main pipe.
2. There is a gas source, no signal. (1) Conditioner fault, (2) Signal tube leakage; (3) Air leakage of the bellows of the positioner; (4) Conditioning omentum diaphragm damage.
3. The positioner has no air source. (1) Filter blockage; (2) Pressure reducing valve fault I (3) pipeline leakage or blockage.
4. The positioner has an air source, no output. Positioner saves hole blockage.
5. There is a signal, no action. (1) The valve core falls off, (2) the valve core is stuck with the society or with the valve seat; (3) The stem is bent or broken; (4) Frozen or scorched dirt on the seat and spool; (5) The actuator spring is rusted due to long-term use.
(2) The action of the conditioning valve is unstable. The symptoms and causes are as follows:
1. The pressure of the air source is unstable. (1) The compressor capacity is too small; (2) Faulty pressure reducing valve.
2. The signal pressure is unstable. (1) The time constant (T=RC) of the control system is inappropriate; (2) The output of the conditioner is not stable.
3. The air source pressure is stable, and the signal pressure is also stable, but the action of the conditioning valve is still unstable. (1) The ball valve of the amplifier in the positioner is not tightly closed by dirt wear, and the output oscillation will occur when the air consumption is particularly increased; (2) The nozzle baffle of the amplifier in the positioner is not parallel, and the baffle cannot cover the nozzle; (3) Air leakage from output pipe and line; (4) The rigidity of the actuator is too small; (5) The friction resistance is large during the movement of the valve stem, and there is a blockage phenomenon in the contact with the phase.
(3) Conditioning valve oscillation. The symptoms and causes are as follows:
1. The conditioning valve oscillates at any opening. (1) Unstable support; (2) there is an oscillation source nearby; (3) The valve core and bushing are seriously worn.
2. The conditioning valve oscillates when it is close to the fully closed position. (1) The conditioning valve is selected to be large, and it is often used under a small opening; (2) The medium flow direction of the single-seat valve is opposite to the closing direction.
(4) The action of the conditioning valve is dull. The phenomenon of dullness and its causes are as follows:
1. The stem is dull only when acting in one direction. (1) The diaphragm is damaged and leaked in the pneumatic film actuator; (2) The "O" type seal leaks in the actuator.
2. The valve stem has a dull phenomenon when it reciprocates. (1) There is sticky blockage in the valve body; (2) PTFE filler transformation hardening or graphite-asbestos filler lubricating oil dry; (3) The filler is added too tightly, and the friction resistance increases; (4) Because the stem is not straight, the friction resistance is large; (5) Pneumatic conditioning valves without positioners will also lead to dull action.
(5) The leakage of the conditioning valve increases. The reasons for the leak are as follows:
1. When the valve is fully closed, the leakage is large. (1) The valve core is worn out, and the internal leakage is serious, (2) The valve is not adjusted and closed tightly.
2. The valve cannot reach the fully closed position. (1) The pressure difference of the medium is too large, the rigidity of the actuator is small, and the valve is not tightly closed; (2) There are foreign bodies in the valve; (3) Bushing sintering.
(6) The adjustable range of flow becomes smaller. The primary reason is that the valve core is corroded and becomes smaller, which makes the adjustable* small flow rate larger.
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