Calculation and selection of the safety valve throat diameter
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After calculating the required discharge area based on API standards, should the throat diameter of the safety valve be selected one size larger? I have a few valves of the Crosby JOSE series; the calculation result is 1877 mm2. Instead of using size ‘L’ with a value of 3.22 In2/2078 mm2, size ‘M’ is used instead, giving a value of 4.065 In2/2622 mm2. Could anyone tell me what considerations led the designers to make this choice? Thank you
It might be an internal rule. Maybe it was purchased by the owner.
First, determine whether your leakage rate is correct. Second, the valves manufactured by suppliers are chosen based on the leakage rate; there is no size available that matches your leakage rate (safety valves are generally produced in standard sizes and are not designed or manufactured specifically according to individual calculations)