Determining GPM through a Circuit Setter

[dblyle]

Ok, here is my problem. I have a client that buys water from his building. He is on the top floor of a huge mall and they recently renovated the chill water piping system. My client doesn't believe that he is receiving the correct amount of water so he asked me to verify that he is getting all the water he needs.

Anyway, my initial feeling is that the building is supplying enough water but lacks the sufficient head to push it through his system. To prove this, I bought a 4" circuit setter (Bell and Gossett) and installed it on the main supply line into his space. I actually cut a Tee in to the line and, on the bypass side, installed the circuit setter and a hose to the return side. My thought was that I would test flow running the system in bypass and determine the flow rate. Once known, I would then add his system to the loop and determine flow rate. The difference in flow rates would allow me to determine the additional head needed to "push" through his system.

Here is my problem...I have had three (3) balancing contractors read the valve and all give me different answers to the correct water flow through the valve. According to B&G, the Cv of the valves varies with % open setting. According to some of my certified balance guys, the Cv must remain constant. According to B&G's CB Balancing wheel and my pressure readings, as I close the valve, the pressure drop increases and the flow rate increases. That makes no sence to me.

So, if anyone has had any experience in this area or run across this problem before, please let me know what I may be doing wrong.

Thanks.

-LYLE

 

[walkes]

Forgive me if my information is outdated. But, I was looking at my B&G Circuit Setter Balance Procedure Manual, one of the images shows the circuit setter with the open to closed gauge on it where the numbers vary from 0 to 40 which I believe is the angular degree setting not a percent open setting. Therefore the information on your balance wheel is correct but the interpretation is not. 0 is fully open and 40 is approaching fully closed.