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          What are the conditions of the regulating valve?

          發布時間:2018-11-13 關注次數:

          What are the conditions of the regulating valve?

          a) Adjust the valve vibration. The symptoms and causes are as follows:

          1. The regulator valve vibrates at any opening. 1 support is unstable; there is vibration source near 2; 3 valve core and bushing wear seriously.

          2. The regulator valve vibrates as it approaches the fully closed position. 1 The regulating valve is selected to be large, and is often used at a small opening; 2 The flow direction of the single seat valve is opposite to the closing direction.

          b) The adjustment valve is slow. The symptoms and causes of dullness are as follows:

          1. The valve stem is slow to operate in only one direction. 1 diaphragm breakage leakage in pneumatic diaphragm actuator; 2 "O" seal leakage in the actuator.

          2. The valve stem is dull when reciprocating. 1The valve body is stuck with glue; 2Teflon filler metamorphic hardening or graphite-asbestos filler lubricating oil is dry; 3The packing is too tight, the frictional resistance is increased; 4The frictional resistance is large due to the stem is not straight; 5 The positioner's pneumatic control valve can also cause slow movements.

          c) The leakage of the regulating valve is increased. The reasons for the leak are as follows:

          1. The leakage is large when the valve is fully closed. 1 The valve core is worn, the internal leakage is serious, and the 2 valves are not adjusted well.

          2. The valve does not reach the fully closed position. 1 The pressure difference of the medium is too large, the rigidity of the actuator is small, the valve is not tight; 2 the valve has foreign matter; 3 the bush is sintered.

          d) The flow adjustable range becomes smaller. The main reason is that the valve core is corroded and becomes smaller, so that the adjustable minimum flow rate becomes larger.

          Understand the failure phenomenon and cause of the pneumatic regulating valve, and take measures to solve the problem.

          Regulating valve to increase the throttle gap method

          If the solid particles in the medium or the slag and rust that are washed away in the pipeline cannot be blocked or jammed due to the throttle opening, the throttle with a large throttle gap can be used instead. Valves and sleeves of windows and openings can be easily eliminated because their throttle areas are concentrated rather than circumferentially distributed. If it is a single or double seat valve, the plunger valve core can be changed to a "V" shaped valve core, or changed to a sleeve valve. For example, if a chemical plant has a regulating valve that is often stuck, it is recommended to use the sleeve valve to solve the problem immediately.