Regarding the calculation of flow restriction orifice plates, standard HG/T 20570-95: critical flow rate pressure ratio
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This post was last edited by goldliyang on 2017-7-6 at 21:29. Hello everyone, I have a question regarding the calculation of flow control orifice plates, in accordance with the standard HG/T 20570-95. The medium is gas. (1) In section 2.0.2.1 on page P446, it is stated that the pressure ratio after the flow control orifice plate to the pressure before it should be no less than 0.55; thus, p2/p1 ≥ 0.55. (2) In section 3.0.4 on page P449, it is said that if such orifice plates are used for flow control, then p2/p1 must be ≤ the critical flow rate pressure ratio rc. I have two questions. First, what is the definition of the critical flow rate pressure ratio rc? Second, the value of rc is listed in P458; it can be seen that in most areas of the table, even when the relevant parameter values (such as d0 and D) are changed, this value remains less than 0.55. Assuming the corresponding rc is 0.45, doesn’t that mean 0.55≤p2/p1≤0.45, in which case it’s impossible to find a solution? .
This post was last edited by zemxlyf on 2022-9-19 22:49. No one has replied in several years? It seems that 3.0.4 should be P2/P1≥γc, because P2 cannot be less than the critical pressure.