Problems with the dual solenoids of the compressor anti-surge valve

The diagram shows a parallel connection, which increases reliability

One should not rely solely on flowcharts (which are merely illustrative); instead, it is necessary to examine the pneumatic circuit diagrams of the valves. There are essentially two approaches: single-power-loss interlock (reset with dual power supply) and double-power-loss interlock (reset with single power supply). It is important to consult the specialist team to determine whether interlock failure or false interlocks pose a greater risk to the equipment or the manufacturing process, before making a decision – instruments alone cannot cover everything. Example: The XV valve at the inlet of the circulating compressor to prevent backflow – PID indicates single-power-loss interlock, but in practice a double-power-loss interlock is used to close the valve (with reset upon single power restoration).

It is about whether the valve is open, closed, or held in a specific position in case of a fault, as well as whether the priority is to protect the equipment or to protect the pipeline network. Is my understanding correct?

Xiao Wu, the anti-surge signal comes from the ITCC; it seems to be a fail-safe solenoid valve. Both solenoids are normally powered, and if either one loses power, the anti-surge valve (FO) opens

Your understanding is correct. Valve failure refers to air loss (cylinder pressure drop), which is clearly a FO. What is being considered now is the relationship between the safety and operability of logical programs (and circuits), and which one should take precedence; this is a question that needs to be answered by the equipment and process designers, with the instruments being implemented in accordance with their requirements. There is also a positioner on the valve for continuous opening adjustment.

On the forum, one can even meet leaders – truly, you never know where you’ll meet someone in life! After checking relevant information, the parallel installation of solenoid valves enhances reliability; the failure of any single redundant solenoid valve does not affect the system’s functionality. The system can only stop working when both redundant solenoid valves fail. For this legend, the designers used dual solenoid valves, and a \"shuttle valve\" was added at the point where the air circuits meet. Even if one solenoid valve loses power and the corresponding circuit of instrument air loses pressure, the shuttle valve can prevent pressure release, allowing the other circuit to continue operating normally. Thereby reducing malfunctions and the resulting production fluctuations or shutdowns. The mathematical relationship for the reliability of a system with redundant solenoids is as follows: Failure probability: F = F1 · F2. Reliability: R = 1 – F. Here, F represents the failure rate of the system with redundant solenoids; F1 is the failure rate of the redundant solenoid SV1, and F2 is the failure rate of the redundant solenoid SV2. R denotes the reliability of the system with redundant solenoids. Assuming that the failure rate of each of the two redundant solenoids is 0.1 (with a reliability of 0.9 for each solenoid), the failure rate of the system with redundant solenoids is 0.01, while its reliability is 0.99 – a significant improvement over the reliability of a single solenoid.

“The shuttle valve ensures that even if one solenoid valve loses power and the corresponding supply of instrument air is reduced in pressure, it can prevent pressure loss by blocking it, allowing the other circuit to function properly. ? You can attach the illustration