Do control valves consume air?
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I’m just starting to learn about air compressor stations. Our compressors produce over 6,000 cubic feet of purified air, which is sent to several devices in the factory; control valves are generally used for regulating this flow. I would like to ask whether the use of control valves consumes air, and if so, how much air is consumed?
The pneumatic actuators for control valves, valve positioners, and filter pressure reducers all consume air. The exact air consumption can be found in the product specifications. Generally, the air consumption of pneumatic actuators is approximately 380 L/h, while that of filter pressure reducers and valve positioners is 200–300 L/h.
Refer to the **standards** – different positioners have varying air consumption rates; generally, it is calculated at 1 L/min. For specific details, you can check the standards
The force of the compression spring is maintained by wind, and it is generally considered to be in the range of 0.7 Nm3/h to 1.5 Nm3/h. Refer to HG/T20510-2014 Code for Design of Instrument Air Supply.
The pneumatic accessories of control valves (positioners, pressure reducers, etc.) all consume air; in the absence of specific data, an estimate of 5 liters per minute is used. The control valve itself consumes no gas when it is stationary; gas is consumed only when it moves. Therefore, the total amount of gas consumed needs to be estimated based on experience (standards), the frequency of operation, and the probability that multiple valves will operate simultaneously. When supplying air to control valves, leaks in the pipeline network must be taken into account. .
Even staying still consumes energy! Just like in tug-of-war, to maintain a certain position (such as 40% opening), air is used to sustain the force between it and the spring; if no air is used, it will be C or O.
Just like tires, as long as there are no leaks, the tire pressure can be maintained without having to add air.
For mechanical positioners, take it apart and check the nozzle to find out.