The valve, the warning hydroblow

The valve, the warning hydroblow with electromagnetic management of model 735-55-M – hydraulically the operated adjusting valve with the diaphragm drive.
At blackout the valve immediately opens even before the pressure drop in system connected with a pump stop.
The open valve 735-55-M dumps the come-back wave of an elevated pressure and prevents hydroblow.
Feeling change of pressure in system, the valve is smoothly and hermetically closed.