Steam Coil Air Heater (SCAH)
Steam Coil Air Heater (SCAH)
(OP)
Is there any way to quantify a leak based on lost pressure. A SCAH being pressure tested with air to 25 psig. Over a two hour period the pressure decays slowly to 5 psig. Is there criteria for how long pressure must be held to determine if there are no or no significant leaks leaks? I was not the one who did the test so I do not know if the rate of pressure drop was quick at first and then slowed and the internal pressure got lower.





RE: Steam Coil Air Heater (SCAH)
what was the purpose of a pressure test with 25 psig? What I do normally is a leakage test with air slightly above atmospheric pressure ( 0.5 bar ) and check with soap water for leaks at weldings and flanges. The pressure test should be done as hydrotest with water in case of a steam coil with at least 1.3 x operating pressure. In case of leaks the pressure will drop within minutes and you should be able to detect the leaks by dripping water.
Hope this helps.
RE: Steam Coil Air Heater (SCAH)
RE: Steam Coil Air Heater (SCAH)
Assume you expanded the gas to a pressure of 20 psig. Now the actual volume should be (20+14.7) x V. This comes out to be 14.4% (39.7/34.7) greater than volume at 25 psig. But as your coil volume remains constant, the leakage is 14.4%.
Though this method is not perfect it will give you some approximation and is generally used.
As far as pharmaceutical application is concerned, we don't bother if the leakage is less than or equal to
1.3 mBar/Minute.
RE: Steam Coil Air Heater (SCAH)