Stating that it is primarily for use in district cooling applications, Danfoss has announced its full range of self- acting differential pressure controllers (DPCs). The basic function of a DPC, say Danfoss, is to maintain a constant and stable differential pressure across Motorised Control Valve (MCV), from 100% to 0% flow conditions. As a result, the valve authority of the control valves is improved.

The manufacturers state the following salient features of the DPCs:

• Tailored/adapted setting range, which fit to almost all requirements.
• Because of pressure relieved valves, the DPCs are able to close off against high pump pressure – 10-20 bar.
• The VFG valves come with a soft sealing option – EPDM rubber – in case of low leakage requirements.
• Self Acting Actuators (AFP) are fitted with a pressure-limiting valve in the rubber diaphragm in order to protect it against excess pressure.

The DPCs have the following specifications:

• Size : DN 15 to 250
• PN 16,25 & 40
• Mounting : Flow or return

The manufacturers specify that the two impulse tubes (copper tubes), which transmit chilled water upstream and downstream pressure, should be installed before and after the MCV.