Circuit Balancing Valve, Circuit Setter, PRV?
Even though people explain it to me, I still don't quite understand what is the difference between a circuit balancing valve and a pressure reducing valve. Balancing valves are used in bypass situations and have an adjustable setting. Sounds like a pressure reducing valve to me. Also, what is the difference between a circuit setter and a circuit balancing valve? Any help would be greatly appreciated.
A Pressure Reducing Valve is used to obtain a desired downstream pressure. The valve is adjusted with that goal in mind.
The
fact that a valve is adjustable does not necessarily make it a PRV. A
balancing valve might be used to balance the flow in a circuit to a
desired flow rate. They are not only used in bypass situations. They
might also be used when there are a number of circuits coming into one
common manifold, and one wants to obtain an equal pressure drop through
each circuit (balance the circuits). The goal is different to the PRV.
The purpose of a balance valve is to balance/control the flow in a
particular branch or circuit. Even in coil systems with two-way control
valves (i.e., no bypass), you don't want the coils closest to the pump
to get all the flow. It's similar to manual volume dampers in HVAC duct
systems. It is probably true that the pressure is incidentally reduced
through a balance valve.
The Circuit Setter is a registered
trademark of ITT Bell & Gossett. It is a balance valve. The
importance of getting balance valves or circuit setters vs. just a globe
valve or something that you can throttle, is that it comes with
integral valved read-out ports and a memory stop indicator. That way
you can measure the pressure differential across the device (like an
orifice flow meter) and with a manufacturer-furnished chart establish
the flow. The memory stop is useful in that you can shut off the valve
when necessary, but then you can return it to the the formerly balanced
position when you want to put the circuit back in service.
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