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Vacuum condensate return unit testing

nreeve Member Posts: 1
I'm wondering if anyone can help me understand how to test the CFM rating on a vacuum condensate return system. I would like to test some of the systems we're selling to ensure they're doing what is advertised, but I'm not sure the process / setup required. I've seen a post on here where @Pumpguy stated "This can be easily measured by valving off the vacuum pump's receiver tank, and fitting one or more orifices to the tank that are open to atmosphere. By knowing the size of the orifice(s), and the resulting vacuum, I can tell you your CFM. For this test to be accurate, all air entering receiver tank must come from atmosphere through these orifices." and I'm hoping someone can elaborate on this process.


  • Jamie Hall
    Jamie Hall Member Posts: 23,310
    Just what @Pumpguy said. The principle is quite straightforward. Given the size of the orifice, a very specific rate of gas flow will occur for a given pressure differential across the orifice. This reference is as good as any: https://engineersforengineers.com/2021/10/11/orifices-flows/?msclkid=89cbb3a1c71b11ecac4c0780a477e5ab

    If you know the vacuum gauge, then that's your pressure differential (or can be converted to it -- the equation they give is, for some reason, in water column...) and you can calculate the flow. As @Pumpguy said, though, all of the flow has to go through the orifice, which is why you valve all the other inlets off.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Pumpguy
    Pumpguy Member Posts: 659
    Attached to this reply is the file from my website describing the testing procedure for vacuum condensate return pumps.

    If you can give me some idea of what brand and type of vacuum heating pump you have, its capacity rating, and what level of vacuum you are wanting to achieve, I can suggest one or more orifice sizes to use.

    Should you wish to pursue this orifice testing project further, please feel free to contact me directly and I will do all I can to help.
    Dennis Pataki. Former Service Manager and Heating Pump Product Manager for Nash Engineering Company. Phone: 1-888 853 9963
    Website: www.nashjenningspumps.com

    The first step in solving any problem is TO IDENTIFY THE PROBLEM.