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Valve Selection (Valve Authority & Rangeability)

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AasifKhan
AasifKhan Member Posts: 2
in Thermostats and Controls
HI,

I have something very basic to ask about CONTROL VALVE selection. Hope i will someone who could reply in the best and easiest way.

1. What is Valve Authority (In layman' term) and how to calculate it. What is the formulae. Usually we have flow rate only and we assume system DP as 5psi. From Flow and DP i calculate Cv and basis of CV globe valve is selected. Now how i can calculate Valve authority out of it. If someone can explain.

2. What is Valve Rangeability (usually it is 50:1 for Globe valves) so what does this 50:1 means.

Please reply shall be very very grateful.

Comments

  • hot_rod
    hot_rod Member Posts: 22,131
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    It would be tough to put an explanation in a sentence or two.

    Here is one of the best that I have found, thanks to Robert Bean for providing so much useful info. Most in laymen's term:)


    http://www.healthyheating.com/Control-Valve-Theory/Control-Valve-Theory-pg1.htm#.WFkkg7GZO7Y
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • PinkTavo
    PinkTavo Member Posts: 64
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    @hot rod I went to the site you referenced. Are these web-based classes? I can't find a place to "sign-up" for a class...or cost if any. What am I missing?
  • Zman
    Zman Member Posts: 7,569
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    Those look like they came from Integrated HVAC, a course Robert Bean taught through heatspring.com.
    I would highly recommend it if it is offered again.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rod
    hot_rod Member Posts: 22,131
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    PinkTavo said:

    @hot rod I went to the site you referenced. Are these web-based classes? I can't find a place to "sign-up" for a class...or cost if any. What am I missing?

    I think Robert puts the slides from his presentation on his site for all to see. Reading through and looking at the pics gives you a pretty good understanding of the concepts. I'm not sure if he presents this topic on a regular basis, check his calendar at the site.

    Entire textbooks have been written on balancing if someone want to go that deep.

    TA Tour& Andersson had some great balancing and valve selection design manuals years ago, not sure they exist as that name anymore, maybe Victraulic merged them?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream

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