Netafim has the perfect solution for assuring your automatic flush cycle on your filter performs at optimum efficiency. The Pressure Sustaining Normally Open (PSNO) valve maintains the correct pressure between the filter and the valve ensuring sufficient pressure to complete the flush cycle. This saves you money by reducing water usage and not needing a larger pump plus reduces maintenance on the filter. Ideal for all types of automatic flush filters.
The valve is preassembled from the manufacturer, consisting of the basic valve, a normally closed solenoid, a pressure sustaining pilot and an accelerator relay. The inline valve is easy to install, has low losses at high flow rates and is constructed of durable PVC. Manufacturer recommends sizing the valve in relation to the flow rate not the pipe size, see technical specifications for details.
PSNO Valve Operation
- A PSNO Valve is always installed downstream of the filter. During normal 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.