How is the differential pressure before and after a valve generally calculated?
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When selecting valves, the pressure difference before and after the valve needs to be taken into consideration; this value is usually provided in the process specifications. However, if the material flows solely due to gravity, how should this pressure difference be calculated? The process specifications only state that the pressure is normal before the valve and also normal after it – isn’t that incorrect?
It definitely can’t be right; there must be pressure on it.
The source of the parameter is generally the pressure from a pressure source such as a pump on the side before the valve, while it is usually the pressure required by the process on the side after the valve; this value can be obtained quite easily.
For gravity, refer to Bernoulli’s equation; there is a formula involving density * gravitational acceleration * height. Based on density, it is possible to convert this value into mm of water, which is equivalent to MPa. However, it’s difficult to calculate pipeline pressure loss
The original poster, take a look at this post: http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1415692