· Static balancing in variable volume systems can present problems.
· When control valves start closing, the characteristics of the system will change.
· Static commissioning valves like Fixed Orifice Commissioning Valves are pressure dependant so a change in pressure will result in a change in flow rate.
· Even if the valves are proportionally balanced, overflows and underflows will still occur.
· The solution is to use Dynamic balancing valves that are pressure independent so that flowrates will remain constant if there are pressure changes elsewhere in the system.
· A Differential Pressure Control Valve is a self-operated device which monitors the difference in pressure between the flow and return pipework and compensates to maintain a constant differential pressure at that point in the circuit.
· The DPCV protects control valves in a branch from rising pressure and stabilises the water flow and temperatures within the branch.
· The closer the DPCV to the control valve, the higher the authority
· The most efficient method of balancing would be to fit DP control on each terminal unit which would give the control valve very high authority.
· The solution is to combine a DPCV with a control valve and a balancing valve.This is a dynamic, Pressure Independent Balancing Control Valve (PIBCV) or combination valve.
· As the valve is pressure independent the terminal unit will be unaffected by pressure fluctuations elsewhere in the system so the valve maintains a constant flow rate if the differential pressure alters.
· The integrated DP controller gives the control valve 100% authority
Dynamic Valve Family