This project investigates the feasibility of achieving further water conservation using an advanced pressure regulating valve (APRV) technology that modulates pressure based on demand to optimize water reduction. The demonstration was conducted on a controlled pipeline test bed located at the U.S. Army Engineering Research and Development Center in Vicksburg, Mississippi to validate water savings potential, along with the overall functionality and reliability of the APRV. The objectives of this project were as follows:
Unlike conventional pressure regulating valves (PRVs) that have a single downstream pressure set point, the APRV design has two constant downstream pressure settings (normal and low-pressure settings) that adjust distribution system pressure in response to the flow rate through the distribution system. The APRV saves water by operating at the lower pressure setting during low flow requirements that occur during periods of low demand (e.g., overnight, weekends). However, as water usage increases, the APRV provides higher pressure to automatically increase flow to the distribution system. The flow trigger point is set based on end user requirements and is adjustable in the field to accommodate future changes in distribution system requirements.
Three APRVs were evaluated: Singer 106, Cla-Val 98-06, and Cla-Val 131. All three APRVs were able to reduce water loss up to 30% in comparison to the baseline (with the water supply at 95 pounds per square inch [psi]). Based on the test data, 10% water reduction from leakage was achieved with a high to low pressure delta of 15 psi. For all APRVs tested, the maximum APRV flow achieved was 750 gallons per minute (gpm), exceeding the minimum UFC fire flow requirement of 500 gpm for one-story, non-sprinklered family housing over a duration of 90 minutes.
The team does not recommend implementing the Singer 106 or Cla-Val 98-06 APRVs due to transition speeds, commissioning pressure transients, and water hammer experienced during testing. The team also experienced manufacturer errors (wrong valve size shipped and a clogged strainer) and issues with temperatures below 32ºF. The project team recommends the Cla-Val 131 for use in isolated tree-type water distributions, but not multi-feed systems.
Current U.S. Department of Defense (DoD) guidance (UFC 3-600-01) no longer allows the use of PRVs on distribution lines or service mains for future designs primarily due to lack of manpower and resources available to maintain existing critical infrastructure. The demonstration testing at ERDC was intended to validate leak reduction and reliability of APRV operations, which aligns with DoD installations’ requirement to take measures to reduce water loss and to improve water use efficiency (Executive Order 13693). A follow-on full-scale demonstration at an operational environment was planned to collect data on APRV performance in the field to assess long-term maintenance issues and to develop guidance for deployment of this technology at DoD installations. This initiative was not completed due to the pressure transients observed when testing the APRVs.
For the two hydraulically actuated valves, the Singer 106 and Cla-Val 98-06 models, issues were experienced with water hammer and the valve closing speed when transitioning from high to low flow rates. This led to unwanted pressure surges and an increased potential for infrastructure damage. The team transitioned to an electronically actuated valve, the Cla-Val 131. For the Cla-Val 131, two out of 10 tests resulted in a pressure transient of 10 psi over 5 seconds, and one test with a pressure transient of 30 psi over 5 seconds. Overall, the Cla-Val 131 presented the lowest amount of pressure transients. Consequently, it is considered to be a more viable alternative than the hydraulically actuated APRVs.