Discussion on the selection calculation of API520 safety valves
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In API520’s calculations for critical conditions in gas media, what does Kd represent when a pressure relief valve is used in combination with or without a rupture disk? How should this phrase be understood?
It is about whether to consider using a safety valve in series with a burst disc. When a safety valve and a burst disc are used in series, a coefficient needs to be taken into account; from what I remember, the value of this coefficient specified in the standards is 0.9
When there are burst discs in series, it is one value; if none are present, it is another value
This refers to whether there is a burst disc at the inlet of the safety valve; if so, a burst disc correction factor of 0.9 must be used when calculating the flow capacity of the safety valve, while if there is no burst disc, the correction factor is 1.