Failures and troubleshooting methods of the piston-type steam pressure reducing valve

The piston-type steam pressure reducing valve regulates the flow of the medium by adjusting the opening of the valve’s closing element inside the valve body, thereby reducing the pressure of the medium. It also utilizes the downstream pressure to adjust the opening of the valve element, keeping the downstream pressure within a specified range. In situations where the inlet pressure fluctuates, it ensures that the outlet pressure remains within the set range to protect downstream equipment used in daily production. The piston-type steam pressure reducing valve is an essential component of a pneumatic control valve. Its main function is to reduce the pressure of the air source and stabilize it to a fixed value, allowing the control valve to obtain a stable air source for adjustment and control.

I. Classification of Piston-Type Steam Pressure Reducing Valves

By Structural Form: It can be divided into diaphragm-type, spring-diaphragm-type, piston-type, lever-type, and bellows-type.

By Number of Valve Seats: It can be classified as single-seat type and double-seat type.

By Position of the Valve Disc: It can be divided into direct-acting type and reverse-acting type.

The operation of the piston-type steam pressure reducing valve is controlled by the downstream pressure. When the pressure sensor detects an increase in the valve pressure, the valve opening decreases; when the downstream pressure decreases, the valve opening increases to meet the control requirements.

The piston-type steam pressure reducing valve – the pressure reduction ratio must be higher than the system value to a certain extent. Even under maximum or minimum flow conditions, it should respond to direct or reverse control signals. These valves should be selected based on the useful control range, typically 20% to 80% of the maximum flow. Generally, they are of equal percentage type or have an equal percentage characteristic. These types of valves inherently have the best flow characteristics and flow range required for proportional control.

There are many types of pressure reducing valves, commonly including: pilot-operated piston-type pressure reducing valve, diaphragm-type pressure reducing valve, bellows-type pressure reducing valve, proportional pressure reducing valve, self-operated pressure reducing valve, direct-acting piston-type pressure reducing valve, back pressure regulating valve, and so on. They are suited for different working media.

Different forms have different specific working principles, but the general principle is: the pressure reducing valve reduces the inlet pressure to a required outlet pressure by throttling the valve element, maintaining a stable outlet pressure. However, pressure reducing valves generally require an inlet-to-outlet pressure differential of ≥0.2MPa.

II. Causes of Piston-Type Steam Pressure Reducing Valve Failure to Reduce Pressure or Malfunction

1.The sealing surface of the main valve or auxiliary valve is contaminated, and the contaminants should be cleaned.

2.The sealing surface of the main valve or auxiliary valve is damaged, and the seal should be re-ground or replaced.

3.The springs of the main and auxiliary valve discs are fatigued or broken; replace with new springs.

4.The feedback channel C-hole is blocked; clear the contaminants in the channel.

5.The diaphragm is fatigued or damaged; replace the diaphragm.

6.The piston cylinder is worn or corroded; rework or replace the piston.

7.The piston ring groove is stuck with the piston ring; remove the piston and clean it.

8.The valve body cavity is filled with condensate; loosen the screw plug to drain the condensate.

III. Methods for Solving Airflow Blockage

1.The valve cover is misaligned during cleaning; remove the valve cover, align it, and reassemble.

2.The gasket has shifted, blocking the inlet and outlet holes; adjust the gasket so the holes are aligned with the inlet and outlet.

3.The auxiliary valve channel hole is blocked; remove the valve cover and clear the debris from the channel.

If you have any comments or interested in our products, please contract me freely in any time.

whatsapp: +86 18159365159

Email:victor@gntvalve.com

WEB: https://lyv-valve.com/