Torch system pressure
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SH 3009 stipulates that the pressure at the boundary of the device should not be lower than 0.15 MPa; however, the safety valve within the device is set at a pressure of 0.35 MPa. If a bellows is used, the back pressure shall be more than 30% of the set pressure, with this back pressure not exceeding 0.105 MPa； Isn’t that a contradiction then? How can this be done?
It is also okay to use the bellows at 50%
But don’t the investment costs increase as well for using diaphragm safety valves for the low-pressure safety valves of the equipment?
That’s not possible. With a set pressure of 0.35, it’s impossible to use a spring-type mechanism; unless you increase the design pressure, but that means extra costs
This post was last edited by altpage on 2017-11-25 at 16:13. I searched throughout SH 3009-2013 but couldn’t find that sentence; only the one in the image was available. Additionally, most of the safety valves in our unit are spring-type, available in two back pressure settings: 0.05 MPa and 0.11 MPa.
The concept of the brother value seems incorrect; my understanding is that it should be 0.35*（1+30%）
How is that possible? Does the safety valve release pressure to relieve high pressure? Release from 0.35 MPaG at constant pressure to 0.455 MPaG?