Excess pressure within a distribution system can give rise to both increased leakage and additional maintenance costs from higher pipe burst frequencies. In the right circumstances, the application of pressure control can quickly reduce costs in these areas and assist in maintaining the reductions. A brief description of the methods is outlined below:
Fixed Outlet Control
Fixed outlet control is the traditional method of control. This method uses no additional control instrumentation and is very cost-effective for areas with uniform topography and demands which do not vary greatly due to seasonal changes.
Time-Based Modulation
Time-based modulation changes the downstream setting of the PRV at specified times. This methodology is very effective for areas with high variability between peak and off- peak demands, ie. the downstream pressure is increased for peak periods and reduced again during off-peak periods. The controller incorporates a modulating pilot, but 2-point control can be effected using a programmable solenoid valve and 2 standard pilots.
Flow-Based Modulation
Flow-based modulation is the optimal control for areas with changing conditions, headloss and fire flow requirements. This type of controller sets the downstream setting of the PRV in accordance with a defined pressure vs. flowrate curve. The downstream pressure modulates automatically as the flow rate changes ie. high flow = high downstream pressure and vice versa.
Installation costs are higher – however, optimal savings and guaranteed fire flows due to more intelligent control, can mean this is the most cost- effective type of control.
The Service modules offered by Sentinel Water Services include:
- Pressure control policy development
- Pressure reducing valve (PRV) operation audits
- System investigations & zone specification
- Zone discreteness testing
- PRV station design, construction and commissioning
- Performance monitoring of installations
- Existing PRV optimisation reviews
- Routine PRV maintenance programmes