Pressure Sustaining Normally Open (PSNO) Valves are the universal solution for all types of filters to maximize flush cycle efficientcy. A PSNO valve will ensure that the filter initiates a backflush cycle with the required pressure by maintaining the correct pressure upstream of the valve (downstream of the filter). Filters flush more efficiently resulting in less maintenance, less downtime and less water and energy used. There is no need for a larger pump, saving capital and operating expenses, to achieve the correct pressure during backflush for proper cleaning.
A PSNO Valve is always installed downstream of the filter. During standard operation, filtration mode, the PSNO Valve is fully open and flow or pressure to the field is not restricted. The solenoid is not energized at this time (See Figure 1).
During the flushing mode, the solenoid is energized and the PSNO Valve partially closes in order to provide the desired pressure to the filter for proper flushing. This is referred to as the sustaining mode. During the sustaining mode, the valve maintains a “set” upstream pressure regardless of flow rate or pressure variations (See Figure 2).
At the end of the flush cycle, the solenoid is de-energized and the PSNO Valve will fully open again.
Pressure Sustaining Normally Open (PSNO) Valves ship pre-assembled by Netafim USA following strict quality standards. The PSNO Valve consists of a Basic Valve, a Normally Closed Solenoid, a Pressure Sustaining Pilot, and an Accelerator Relay (if the valve is 6” and larger).
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