The Hypro VDR50 Control Unit (9910-VDR50) will mount directly onto the Hypro D503, D703, D904, D813, D1064, or D1265 Diaphragm Pumps (the D703 and D904 are discontinued pumps, however there are some used in the field).
The control unit / pressure regulator can disengage the valve for easy gas engine starting and can be remote mounted or attached directly onto the pump. It has a return line that returns to the tank to handle excess pressure and flow. The return line shouldn't have any agitation on the end and should have zero pressure. The pump may damage if you are obstructing excess flow.
The Hypro 9910-VDR50 Control Unit includes: