Pressure sorting
Thread Content
For pressure vessels equipped with safety valves, the relationship between the vessel’s design pressure, operating pressure, and test pressure on the one hand, and the discharge pressure and opening pressure of the safety valve on the other hand is as follows: A. Test pressure ≥ Discharge pressure ≥ Calculated pressure > Design pressure > Operating pressure > Opening pressure; B. Test pressure > Discharge pressure > Calculated pressure > Design pressure > Operating pressure > Opening pressure; C. Test pressure > Calculated pressure > Discharge pressure > Design pressure > Operating pressure > Opening pressure; D. Test pressure > Discharge pressure > Calculated pressure > Design pressure > Opening pressure > Operating pressure. I chose D, but I’m not sure why the discharge pressure is greater than the calculated pressure. Could someone help check if that answer is correct?
The discharge pressure is equal to the design pressure plus the overpressure limit (the smaller of 10% of the design pressure and 0.02 MPa). The calculated pressure is equal to the design pressure plus the hydrostatic pressure of the liquid column. The answer should include an equal sign
It might be better for this topic to remove the calculation of pressure. Take the hydrostatic pressure of a liquid column as an example; it is related to the height of the liquid column, and it is not possible to determine this relationship for this problem.
The calculated pressure is not necessarily always greater than the design pressure