Series S116-52, S1116-52 Combination Surge Anticipator and Pressure Relief Control Valve is designed to minimize the effects of water hammer and pressure surges resulting from: 1) Normal pump starting and stopping operations or 2) Mechanical or electrical power failure situations. The valve senses hydraulic pressure changes above and below the adjustable setpoints of the pilot control system directly from the pump station discharge header. High Pressure Relief Operation: When discharge header pressure exceeds the adjustable setpoint, the valve opens quickly to dissipate the high pressure surge. Low Pressure Opening Operation (Surge Anticipation): When discharge header pressure falls below the adjustable setpoint, the valve opens in anticipation of the returning high pressure wave. This condition normally occurs during a mechanical or electrical power failure situation. stored main valve cover pressure. If header pressure does not recover above the low pressure opening setpoint, stored pressure in the unique hydraulic accumulator system allows the valve to close, avoiding system siphonage or draining the pumping system.