How Does a Direct Pressure Reducing Valve for Saturated Steam Work?

At startup, the pressure regulating bolt is in the loosen state, the inlet steam pressure and the valve seat spring are in the closed state. We begin by turning the pressure regulating bolt on top of the valve clockwise. The bolt moves linearly, pushing the spring downwards, simultaneously lowering the valve diaphragm, controlling the valve to open, and the fluid and outlet pressure begin to increase. The pressure inside the valve body pushes the diaphragm upwards, balancing the spring force. The pressure after the valve increases simultaneously until it reaches the set pressure value, at which point the valve begins to close gradually, preventing the pressure after the valve from exceeding the set threshold.

When the inlet pressure decreases, the balancing force pushing on the diaphragm decreases, so the outlet pressure also decreases simultaneously. At this point, the spring force will be stronger than the balancing force pushing the diaphragm downwards, causing the valve to open wider to maintain the set pressure value. Conversely, when the inlet pressure increases, the outlet pressure reaches the set value, and the valve closes simultaneously. When the system takes in less steam or stops taking steam momentarily, the outlet pressure will increase slightly, and the valve will tend to close gradually.

Common problems at pressure regulating valve stations:

   - The pressure after the pressure regulating valve is equal to the set pressure during operation, but when stopped, the pressure after the pressure regulating valve increases to the inlet pressure of the valve.

   - The pressure after the pressure regulating valve is often fluctuating, sometimes higher, sometimes lower than the set pressure value.

   - The pressure regulating valve diaphragm often ruptures.

   - Slow system heating.

If you are experiencing any of the pressure regulating valve problems listed below, please contact us for advice on solutions.

TL Plus Company specializes in consulting on solutions, equipment, and energy recovery calculations for saturated steam systems. If you need to improve your saturated steam pressure reducing valve system, please contact us via email at sales(at)tlplus-engineering.com

TL Plus Company is the authorized distributor of Watson McDaniel products in Vietnam and other Asian countries.

💡 Reference products

                                                  Pressure reducing type O, Watson Mcdaniel USA