Will a PRV Operate at Zero-Flow Condition?

PRV's are not designed for the situation you described. Most municipalities require either gate or butterfly valves at some interval along major water transmission mains, which would be used to isolate the water main for repairs/maintenance.

My suggestion for you is to leave out the PRV's altogether. They're maintenance intensive and a headache to calibrate unless you know what you're doing + they cost a bundle. If you're installing pilot-operated Pressure Regulating Valves, then they'll work in all flow regimes, including non-flow conditions because they work on differential pressure rather then flow. Please visit the Ross Valve Company, Troy, New York USA for any assistance you may need concerning PRV's.....IF you are conveying fresh water only....no, seawater or brackish water or petroleum products, etc. You can also consult with CLA-VAL in Calif. USA

If your worry is a problem due to a high Pressure Head, then I suggest that you install several hydraulic structures along the pipeline where the pipe exits into a open-top tank which is exposed to atmospheric pressure.....these tanks will serve as your pressure break points, and the water pressure entering the downstream portion of the pipeline (leaving the tank) will be essentially reset to 0 PSIG or atmospheric pressure. Just may sure your tanks are sized properly for efficient hydraulic operation......be very careful with your exit and entrance losses in your hydraulic comps and modeling, otherwise you'll overtop the tank/structure with your fluid.

And don't forgetto investigate installing inline hydro turbines along your pipeline to take advantage of the pressure and velocity heads present in order to generate electricity to run your SCADA equipment and anything electrical at your tank structures and other substations........free energy to tap into!

Pretty simple concept isn't it? Most engineers forget about these simple principles during the design phase of projects and get all wrapped-up in the technological gee-wiz "gizmos"....... Please keep in mind to always utilize the "KISS" Principle whenever possible! Have a great day!

Signed,

CaptMoosie, LPE, PhD

This option is not readily adaptable to the water industry, when you are not just trying to get the water from point A to point B. You have customers to serve in between, and their pressure has to meet a minimum pressure. Also, when you go up and down hills, the design you recommend doesn't adapt. The PRV's operate well in the type of scenario originally described. However, PRV's are not designed to work in zero pressure situations. They are mostly used to regulate a pressure past a point.

M. Adada, which PRV is it, "Pressure Reducing Valve" or "Pressure Regulating Valve"????

There are major diferences between them as far as use, and appropriate and non-appropriate locations for either.....

Ideally, if there are no required service demands along the pipeline you're better off with the control stations that I mentioned before and let gravity and the atmosphere do the work for you instead of mechanical devices which are always requiring maintenance and some sort of upkeep and recalibration....

And even if ther are customers along a certain segment or segments of the pipeline, then it's still possible to use the control stations, but you're going to have to do more design work and system modeling...

No flow across valve = no pressure drop = no pressure control.

Cheers! DZ