I need help figuring out what causes a breathing valve to leak
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The parameters of a flame-arresting breathing valve in our factory are as follows: Serial number, tag number, equipment model to which it belongs, nominal diameter (DN), external dimensions (length×width×height), pressure class, operating pressure, weight (kg), serial number, date of production, manufacturer. Positive pressure, negative pressure: 2BV-701A-2TK-701A, 100-NF-150, 2007, 70×440×700, PN 0.65, 39 Pa, negative pressure: 245 Pa, weight: 98 kg; date of production: 1998.3. It is manufactured by Fushun Petroleum Machinery Factory and is used on the top of a hexane storage tank; the operating temperature is around 65°C, and it has been functioning properly ever since. But recently, hexane liquid leakage was detected from the intake valve side. No issues were found after removing the suction valve; the problem persisted after it was reinstalled. It is currently not in use. That expert, could you please help analyze this situation? Thank you so much!
This post was last edited by yjjpedp on 2009-6-29 at 19:23. In fact, gas was leaked and condensed into a liquid outside. Hexane has a boiling point of 68.7°C, and its saturated vapor pressure at 60°C is 76.36 KPa. Possible reasons: 1. Deformation of the sealing valve seat – since the valve seat is machined after weld overlay without stress relief, it deforms over time, resulting in poor sealing of the suction valve cover. 2. Deformation of the valve disc: The valve disc is made of polytetrafluoroethylene, and temperature changes cause it to deform. 3. It is fitted with the exhaust valve disc; the operation of the exhaust valve causes the intake valve to operate. 4. Debris has entered the sealing surface. Place the intake valve disc on the valve seat and tap it with your finger; if there is a hollow sound, the seal is not tight enough ； Most vent valves these days are of poor quality.