How does the pressure reducing valve work?
The pressure reducing valve is a gate valve that reduces the inlet pressure to the required outlet pressure according to the adjustment, and automatically maintains the outlet pressure stable by the strength of the medium itself.
The pressure reducing valve is an essential part of the self-operated regulating valve. Its specific function is to relieve the pressure and stabilize the pressure of the pneumatic valve, so that the regulating valve can obtain a stable air source power for adjustment and operation.
Do you know the three pressure reducing valves?
At this stage, the immediate effect type pressure reducing valve and the plastic film type pressure reducing valve of the piston machine are widely used in the sales market.
1. Immediately effective pressure reducing valve.
Very simple pressure reducing valve, immediate action pressure reducing valve with flat diaphragm or metal bellows. Because it is separate, there is no need to install an external sensor underneath.
It has the smallest volume and the most economical application of the three pressure reducing valves, and is designed for low to medium total flow rates. Accuracy of immediate acting regulators is typically +/- 10% of the mid-downstream set point.
2. Piston engine pressure reducing valve.
This type of pressure reducing valve integrates two types of valve pilot valve and main valve. Proportional regulators are designed similarly to immediate action regulators.
The exhaust pipe pressure of the proportional pressure reducing valve acts on the piston rod, causing the piston to open the main valve. If the main valve is large and cannot be opened immediately, this design will use channel pressure to open the main valve. Therefore, compared to immediate acting pressure reducing valves, this type of pressure reducing valve has more volume and accuracy (+/- 5%) for the same line size. Similar to the immediate action pressure reducing valve, the pressure reducing valve’s internal structure recognizes the pressure, and there is no need to install a sensor outside.
3. Plastic film pressure reducing valve.
In this class of regulators, a double-pulse damper replaces the piston rod in an internally piloted regulator.
This increased total area of the pulsation damper can open a higher main valve, which exceeds the volume of an internally piloted piston rod regulator for the same line size. In addition, the pulsation damper is more sensitive to pressure transitions, with an accuracy of +/- 1%. The higher accuracy is due to the precise positioning of the middle and downstream sensors (outside the gate valve), and the turbulence of the gas or solution is less.
The pressure reducing valve is very flexible and can use different kinds of proportional pressure reducing valve (such as pressure valve, temperature valve, gas carrier valve, vacuum solenoid valve or several types of gate valve).
The most basic common sense for choosing a pressure reducing valve.
1. Within the range of known torsion spring pressure, the outlet pressure can be continuously adjusted between the highest value and the lowest value, without clogging and abnormal vibration;
2. The soft sealing pressure reducing valve shall not leak within the required time period; the leakage of the metal material sealing pressure reducing valve shall not exceed 0.5% of the maximum data flow;
3. When the total flow of the outlet changes, the error value of the outlet pressure of the immediate effect type should not exceed 20%, and the pilot type should not exceed 10%;
4. When the inlet pressure changes, the outlet pressure error of the immediate effect type should not exceed 10%, and the pilot type should not exceed 5%;
5. The pressure after the valve of the pressure reducing valve should generally be lower than 0.5 times the pressure before the valve;
6. The pressure reducing valve is widely used and can be used as machinery equipment and pipelines for liquid media such as steam, air compression, chemical gas, water, and oil. The amount of medium flowing through the outlet of the pressure reducing valve is generally indicated by the gas flow rate or the total volume flow;
7. The metal bellows immediate effect pressure reducing valve is suitable for low voltage, medium caliber and small steam medium;
8. The immediate effect pressure reducing valve of plastic film is suitable for medium and low voltage, medium and small caliber gas and water medium;
9. The core piston rod pressure reducing valve is suitable for steam, gas and water media of various pressures, specifications and temperatures. If the stainless steel plate acid-resistant steel is used, it can be applied to various corrosive media;
10. Pilot metal bellows pressure reducing valve, suitable for low voltage, medium caliber, small steam, gas and other media;
11. Pilot membrane pressure reducing valve, suitable for low voltage, medium pressure, medium caliber small steam or water and other media;
12. The fluctuation of the inlet pressure of the pressure reducing valve should be adjusted to 80%~105% of the given value of the inlet pressure. If it exceeds this range, it will damage the characteristics of the early pressure relief;
13. The pressure after the valve of the pressure reducing valve should generally be lower than 0.5 times the pressure before the valve;
14. Each torsion spring of the pressure reducing valve is only suitable for a certain outlet pressure range, beyond which the torsion spring should be replaced;
15. When the operating temperature of the medium is high, a pilot piston rod pressure reducing valve or a pilot metal bellows pressure reducing valve is generally used;
16. In places where the medium is gas or water (liquid), an immediate effect membrane pressure reducing valve or a pilot membrane pressure reducing valve should generally be used;
17. When the medium is steam, pilot piston rod or pilot metal bellows pressure reducing valve should be used;
18. In order to facilitate the actual operation, adjustment and maintenance, the pressure reducing valve should generally be installed on the leveling pipeline.
Post time: Apr-25-2022