ELECTRO HYDRAULIC MODEL 118-3 The control of the model 118-3 is via a three-way solenoid. This solenoid may be electrically interlocked to either the pump power or pump starter. If wired to the pump starter, the valve will automatically proceed in the opening cycle on each pump shutdown. Wired across pump power it opens only on pump power failure. Valve opens when solenoid is deenergized - either directly on power failure or through pressure switch on low pressure - remains open for a predetermined time (accumulator fill), then slowly closes. Valve also opens when set point of relief pilot is exceeded, then slowly closes when pressure returns to normal.
ELECTRO HYDRAULIC MODEL 118-4 The model 118-4, provides the basic functions of the Model 118-3. The electronic Surge Commander, is a self-powered module, designed with two selectable modes of operation allowing for finer tuning of the variables of when to open and how long to stay open. Mode A - Opens valve when there is a power failure during pump run accompanied by a down surge in pressure. Mode B - Opens valve when there is a power failure or when there is a down surge in pressure. Both modes prevent unnecessary valve opening caused by power interruptions with no pump running. The time the valve remains open a precise time and is easily adjustable via a digital timer. The valve also opens when set point of the high pressure relief pilot is exceeded, then slowly closes when pressure returns to normal.
HYDRAULIC MODEL 108-SA-3 The control of the model 108SA-3 is via two hydraulic control pilots. A normally open, low pressure pilot that opens the valve when system pressure drops to its set point. This setting is typically 25 psi less than static pressure. The valve also opens when set point of the high pressure relief pilot is exceeded. The valve slowly closes when system pressure returns to normal (pressure is between the settings of the two pilots).