Medium Flow State of Pneumatic Regulating Valve

Under the condition of medium flow, the liquid flow through the pneumatic control valve is proportional to the square root of pressure loss. The relationship between flow rate and pressure loss exists in most valve applications. However, the diversification of raw material processing process is often applied to the media through pneumatic control valves, which is abnormal flow.

When the pressure loss through the valve is small, the viscosity is large, or the Kv value is small, the flow is laminar, and the relationship between flow rate and pressure loss is linear. When the opening of pneumatic control valve is unchanged, the flow rate and flow rate increase with the increase of pressure loss. Under a certain pressure loss, it flows into the transition zone. If the pressure loss on the valve continues to increase, the flow enters the turbulent zone, which is the normal flow state mentioned above.

When the pneumatic control valve has a large pressure loss, at the maximum shrinkage section, the pressure drops to a very low level, so as to reach the vaporization pressure. Because the vaporization pressure of the flowing medium is reached, the vaporization process begins. Pressure buildup occurs after the contraction zone. Return to higher pressure p2, and the bubbles formed in the shrinkage zone are condensed. When the medium flows in the eddy current region, the square relationship between flow rate and pressure is no longer maintained. When the pressure loss of pneumatic control valve increases further, vaporization also develops further.