Proportional Pressure Equals Pressure Management for Municipalities

By Kelly Sulwer, IPEG (a subsidiary of OTP Industrial Solutions)

Pressure control is key for an optimized water distribution system in municipalities. Another term for proportional pressure is demand driven distribution. This means, when installed correctly, proportional pressure control decreases pressure at lower flow demands and increases the pressure at higher flow demands to compensate for pipe friction loss.

Proportional pressure control is especially effective in municipal pump systems since they have long pipe runs and are often oversized for future growth. The pressure requirement is also calculated high, accounting for “fire fight” conditions and using conservative head loss calculations. The end result is an oversized pump with a high pressure set point that will rarely operate in these “worse case” conditions, causing excessive water loss through existing leaks and wasted energy.

To effectively utilize proportional pressure, the percent of friction head of the total required boost pressure must be determined. A consumption pattern or load profile of the water usage is also beneficial to know. This will establish where the pump will operate a majority of the time and help determine how much additional savings can be achieved since there will be less friction head generated at lower flow rates, ultimately lowering the set point.

A few ways to accomplish proportional pressure is remote mounting a pressure sensor or utilizing the built-in logic of the Grundfos MPC controller. Once the controller is programmed with the percent of friction head and preferred adaptation mode (linear or square), it will then utilize the pump’s performance curve and flow estimation software to automatically adjust the set point to compensate for the friction loss seen in the system. This can achieve the following major benefits:

  • Reduction in water leakage from excessive pressure on pipes
  • Reduction in maintenance cost on piping
  • Reduction in energy consumption by utilizing the VFDs more effectively towards the system’s demands
  • Reduction in the amount of pipe burst in the distribution network

The ability to control pressure effectively can lower leakage losses and save overall operating costs. To ensure a properly sized system, contact IPEG to help select the correct size, type and number of pumps best suited for your system’s needs.