Calculation of the maximum actuation time for quick shut-off valves
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While I had nothing to do in the afternoon, I looked up some information. To my regret, I found that there is indeed no unified standard regarding the timing of operation for quick-shut-off valves. Eventually, I came across a paper that provided some insight: in brief, in gas power generation systems, the main function of the quick-shut-off valves in the gas main pipelines is to quickly cut off the gas supply in the event of a sudden power outage, thereby preventing the combustible gases in the furnace from reaching their explosive limit and causing an accident. In other words, the ratio of the gas flow rate to the volume of the furnace during the valve’s shut-off operation must not exceed the lower limit of the explosive limit; otherwise, an explosion will occur, i.e., 0.5△tQ/V
For cut-off valves, it seems that our manufacturing plant does not need to worry about the cutting time; rather, the overall requirements are set out in the project’s process package and by the design institute responsible for the detailed design. Our manufacturing plant simply installs cylinders on the valves and arranges the air supply systems according to the size of those cylinders, thereby meeting the time requirements specified by the designers. Theoretically, any speed you specify can be met, as there is theoretical data to support it; of course, theory is just that – theory – and it also needs to be practical. However, for turn-off times of 1.0S or 0.5S, it is easy to achieve this with small cylinders, such as those of the rack-and-pinion type ； However, it is more difficult for large cylinders like shift forks; it is necessary to enlarge the cylinder bore, increase the exhaust speed, add pilot valves, and if those measures still don’t suffice, resort to faster hydraulic actuators or similar solutions. If you have friends who would like to discuss this, you can do so via email: xuming.li@az-armaturen.cn