Location of the safety valve
Thread Content
When a safety valve on a liquid pipeline vents to a closed system, is it required that the outlet of the safety valve be at a higher level than the venting main, or is it sufficient for the pipe leading from the safety valve outlet to be at a higher level? What factors need to be considered in this regard?
The design of the outlet pipe for safety valves should take into account that the back pressure should not exceed a certain percentage of the valve’s set pressure; for example, in the case of ordinary spring-loaded safety valves, the back pressure should not exceed 10% of the valve’s set pressure. The outlet pipe of the safety valve connected to a closed system should be angled at 45 degrees along the flow direction of the medium, attached to the top of the pressure relief main, in order to prevent condensate in the main from flowing back into the branch pipes and to reduce the back pressure on the safety valve.
If the outlet pipe of the safety valve is inserted at an elevated angle into the discharge main, and the safety valve is located below the bottom of the main, could liquid accumulate at the outlet of the safety valve after pressure release, thereby increasing the back pressure?
Prevent condensate in the main pipe from flowing back into the branch pipes
What was said on the 2nd floor isn’t very comprehensive! Please analyze the gas or gas-liquid mixture. What if there is no condensate or condensed gas?
If it is a gas, then such a situation does not occur, as the pressure difference resulting from the outlet of the safety valve being below the highest point in the pipeline does not lead to an increase in backpressure； In the case of liquids or liquid-gas mixtures, fluid can accumulate at the high point of the outlet pipe of the safety valve, resulting in an increase in back pressure!
The design of the outlet pipe for safety valves should take into account that the back pressure should not exceed a certain percentage of the valve’s set pressure; for example, in the case of ordinary spring-loaded safety valves, the back pressure should not exceed 10% of the valve’s set pressure. The outlet pipe of the safety valve connected to a closed system should be angled at 45 degrees along the flow direction of the medium, attached to the top of the pressure relief main, in order to prevent condensate in the main from flowing back into the branch pipes and to reduce the back pressure on the safety valve. This statement is reasonable for the outlet of safety valves in pipelines carrying liquid materials to be directed into a closed system; under normal circumstances, it also applies to gas-phase pipelines.
For gas-phase pipelines, it is also necessary to consider whether the gas phase will condense; if condensation is possible, the same considerations as for the second floor must be applied.
The outlet of the safety valve should be above the discharge main to prevent water accumulation and reduce pressure
If the safety valves in a closed factory building are distributed fairly widely, and if they must be placed at a higher level than the main pipes, this may require the addition of many platforms, which could affect the aesthetic appearance. How should this be taken into consideration?