Pressure Reducing Valve (Cont.)(2)
4. Pressure Reducing Control Valve with Integral Back-up (106 / 206-PR-SM)
The 106-PR-SM and 206-PR-SM series control valves are engineered to be used anywhere pressure reducing valve failure is unacceptable. These valves have a second and independent operating system superimposed upon the standard primary system. With the assurance of a back-up system, maintenance schedules may be extended as pressures will continue to be controlled even in the event of failure with the primary system.
Under normal pressure reducing conditions, the primary pilot senses the downstream pressure through a connection at the valve outlet. Under flowing conditions, the pilot reacts to small changes in pressure to control the valve position by modulating the pressure above the diaphragm in the lower operating chamber. The downstream pressure is maintained virtually steady at the pilot set-point that is adjustable.
Should the primary pilot system and / or main valve fail to control the downstream pressure, the independent back-up pilot system will begin to operate. It controls the pressure above the diaphragm in the second operating chamber. The back-up pilot is set slightly higher than the primary pilot. The forces now operating in the top chamber assume control of the inner valve assembly and maintain pressure reducing control. During back-up operation only, there is a small (1 USGPM / 0.063 L/s) continuous discharge that should be taken to drain.
The secondary pilot continually senses the downstream pressure. Should there be a rapid rise in downstream pressure for any reason, the secondary pilot will respond quickly, and will pressurize the top chamber. This will compliment the primary pressure reducing controls and provide faster response.
- Ideal for applications where failure is not an option
- Includes a back-up system to protect against diaphragm or pilot failure
- Reduces unnecessary maintenance
- Provides downstream surge protection
5. Pressure Reducing and Pressure Sustaining Valve (106 / 206-PR-R)
The 106-PR-R and 206-PR-R pressure reducing and pressure sustaining valves are based on the 106-PG or 206-PG main valve with the addition of the sustaining pilot 81-RP and pressure reducing pilot PR-160.
Provided the upstream pressure setting is satisfied, the 81-RP pilot is kept open, permitting the valve to be controlled by the 160 pilot. The 160 pilot senses downstream pressure and under flowing conditions, it reacts to small changes in pressure to control the valve position by modulating the pressure above the diaphragm.
Should high demand cause the inlet pressure to fall to the 81-RP pilot setting, the upstream pressure has priority and the valve will modulate to prevent the upstream pressures from dropping below the set-point.
When the valve is modulating to sustain upstream pressure above the minimum 81-RP pilot set-point, the downstream 160 pilot may try to open the valve to maintain its set-point, but upstream has priority and downstream pressures will fall below expectations.
In typical applications, the reduced port model 206-PR-R is often the best selection.
- Excellent low flow stability
- Ensures minimum upstream pressure
- Easily and precisely set downstream pressure
6. Pressure Flow Control (Modulation) Valve (106 / 206-PFC)
The PFC valve alters and controls pressure with flow to create virtually constant pressure at the critical pressure point in a system. It will also automatically adjust for distribution friction losses. The PFC valve will deliver consistent performance as it has no electrical components and is not affected should the valve chamber be flooded. The valve may be used wherever a standard PRV is installed.
- Reduces pressure when demand is lower resulting in reduced leakage losses and pipe breaks
- Compensates for pressure loss in a long pipeline to deliver virtually constant pressure at all times at a distant point
- Simple to set-up and adjust