What form is good for a steam pressure relief valve? ? ?

There are three types of pressure relief valves in total. Direct-acting pressure relief valve. The simplest pressure relief valve is the direct-acting type, equipped with a flat diaphragm or bellows. Since it is a standalone structure, there is no need to install external sensing wires downstream. It is the smallest in size and most cost-effective of the three pressure relief valves, designed specifically for medium to low flow rates. The accuracy of directly-acting pressure relief valves is typically +/−10% of the downstream set point. Internal guide piston pressure reducing valve. This type of pressure relief valve combines two types of valves – a pilot valve and a main valve – into one. The design of the pilot valve is similar to that of a directly-acting pressure relief valve. The exhaust pressure from the pilot valve acts on the piston, causing it to open the main valve. If the main valve is too large to be opened directly, this design uses the inlet pressure to open the main valve. Therefore, this type of pressure relief valve offers higher capacity and accuracy (+/-5%) at the same pipe size compared to directly acting pressure relief valves. Similar to direct-acting pressure regulators, the pressure regulator senses pressure internally, eliminating the need for external sensor wires. External pilot-operated pressure relief valve. In this type of pressure relief valve, dual diaphragms replace the piston found in internal pilot pressure relief valves. This increased diaphragm area enables the opening of a larger main valve, and at the same pipe size, it has a higher capacity than internal pilot piston pressure relief valves. Furthermore, the diaphragm is more sensitive to pressure changes, with an accuracy of +/-1%. The higher accuracy is due to the positioning of the downstream sensing wire (outside the valve), where there is less turbulence of gas or liquid. This pressure relief valve is highly flexible, allowing the use of different types of pilot valves (such as pressure valves, temperature valves, air loading valves, solenoid valves, or a combination of several such valves). As can be seen from the above, external pilot-operated pressure relief valves are more stable and reliable, but they are also more expensive; the most commonly used type is still the pilot-operated one. Strainers should be installed before and after the steam pressure reducing valve; otherwise, water accumulation in the valve can lead to malfunction of the pressure reduction function. A filter is placed before the pressure relief valve. Abroad, there are valves that combine hydrophobicity, pressure reduction, and filtration functions.