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CO2 Flow Rate

  1. Feb 23, 2015 #1
    Hello guys,
    I need to calculate the flow rate for the following system. 2 lines of CO2 cyclinders at 60 bar. Each line (1/2'') goes to a 1/2'' PSV valve. Downstream the 2 PSV the line are collected together into 1'' pipe.
    The two PSV are identical and as per datasheet they have the following characteristics:
    - max volume flow (working condition): 24,669 m^3/h
    - max volume flow (standard condition): 4265,116 m^3/h
    - max mass flow: 8372,849 kg/hr
    First question: Do you think it is possible to calculate the flow rate trhough the 1'' pipe with the datas above?
    second question: don't you think that 8372,849 kh/hr are a huge quantity considering that all this mass with pass through 1/2'' hole?
    Thank you very much!
  2. jcsd
  3. Feb 23, 2015 #2


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    Gold Member

    Is this a sustained flow? Carbon dioxide has a huge Joule-Thomson coefficient, and it's no trick at all for a flow path to freeze closed at even small constrictions. You say PSV: this is to relieve a system to prevent overfilling of bottles?
  4. Feb 23, 2015 #3
    The flow will occure in case, during CO2 discharge for fire extinguish, pressure in the line will go for some reason above 170 Barg (PSV set point). Under this circumstances I will have flow through the system (CO2 nozzles) plus flow through the 2 PSV valves which will relieve the pressure. I need now to calculate the flow on the two (1/2'') lines downstream the PSV's having just data sheet of the valves and pressure upstream each valve (170 Barg).
  5. Feb 23, 2015 #4


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    Staff: Mentor

    What are your professional education and certifications for being given the job of designing this fire extinguishing system? Why are you asking on an Internet forum how to design a system that has life-saving (or not) ramifications?
  6. Feb 24, 2015 #5
    The system is already designed... i wanted just to double check backpressure downstream the PSV valves and i have just asked feedback on how to calculate flow rate of CO2 gas flow... not to design the system, but anyway... you're right...maybe i shouldn't ask such kind of info trhough a forum just thought it could be interesting also for others.
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