The pressure relief valve regulates the outlet pressure and flow rate
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For laboratory gas use, when the consumption is low (below 200 cubic meters per hour), the flow rate remains stable. However, when the gas consumption is high, the gas flow rate fluctuates significantly; at a consumption of 400 cubic meters per hour, these fluctuations can reach as much as 60-70 cubic meters per hour. It is possible to clearly hear intermittent filling sounds coming from the second gas storage tank (with a capacity of 8 cubic meters), and the flow rate also fluctuates in accordance with the appearance and disappearance of these filling sounds. The air supply system used in this laboratory is as shown in the diagram. The compressor generates compressed air at a pressure of 0.6 MPa; its output volume is sufficient, at 996 cubic meters per hour. After passing through a 4-cubic-meter air storage tank for buffering, the air pressure is reduced to around 0.2 MPa by a pressure regulator, after which it enters another 8-cubic-meter air storage tank (the outlet of the pressure regulator is directly connected to this tank). From there, the air is delivered to the devices that require it using a vortex flow meter, and the amount of air used is controlled by a ball valve located behind the vortex flow meter
Positive-displacement compressors do not use outlet pressure buildup to regulate flow.
Pressure relief valves generally come with flow loss
Thank you. We use screw compressors, which also belong to the positive-displacement type. How can we stabilize the flow rate?
Use a variable frequency drive or a control valve installed on the line from the outlet back to the inlet.
The pressure relief valve has insufficient flow rate; use one with a larger capacity
Well, thank you very much for your response. Considering that the quality of the pressure regulator used earlier might not have been up to standard, we added a DN125 pressure regulator behind the 8-cubic-meter storage tank. When adjusting the flow rate, we found that the fluctuations were around 30, which is sufficient to meet the requirements of the experiments. Now we are considering further optimizing the pipeline in order to achieve a more stable outlet flow rate. Please give some advice, thank you!
This post was last edited by Watt Energy Saving on 2017-7-29 at 19:12. The position of the pressure relief valve is incorrect; as the specific volume increases significantly after pressure reduction (and density decreases), the amount of air that can be stored after pressure reduction is less than 30% of the original amount. It is recommended to use a pressure reducer at the gas point; if multiple devices are in use, do not rely on a single pressure reducer – instead, use individual devices for pressure reduction. If pressure reduction at the main pipe is necessary, it is recommended to use parallel pressure regulators for step-controlled reduction, which will yield a better pressure reduction effect
Parallel pressure reduction, step control, for conditions with large flow rate variations