Pressure Reducing Valves in Underground Mine

[Cruiser2522]

We've been struggling with commissioning a new PRV system for our mine water supply in our underground shaft mine here over the last few months. We are using 4" Singer 106-PR's and they are located on levels ranging from 300' to 600' apart with a total drop of around 6000'. We are finding these valves much too tempermental for the underground applications we're dealing with, we find that with any air entering the system they fail in either a completely opened or closed state, which will lead to cascading failure down the line. We've been working with Singer extensively and basically we've given up on these valves.

In our other older shaft we are using 3" Cash Acme E-56's but the levels are closer there and only are facing 150 feet of head on top of the 100 psi set point. The Cash Acme valves are easy to setup and use but another problem with them is that when low or no flow situations arrise I believe the system will equalize and we will get no pressure regulation leading to pressure reliefs at the levels opening until the pressure is again regulated and then the cycle would start again.

So basically I'm looking for suggestions on some valves which can handle the higher pressure required than the Cash Acme and still provide regulation under low or no flow situations but are simple and robust like the Cash Acme. Accuracy is not super critical if we can reduce from 200-300 psi and hit a target in the 90-110 psi range I'd be happy.

Any help with this would be greatly appreciated. We've dumped over a quarter of a million bucks into this system so far and don't have anything remotely functional yet.

 

[hydrae]

What are the flows you are working with?
How are you getting rid of any air?

I am guessing the cascading failure is one valve closes up (for whatever reason) and the following valves see no pressure upstream so they open wide trying to maintain setpoint and not able to. Then when water is restored the valve just send it right on through and then wham the pressure just shoots right on past the sepoint and bad things happen.

You can add a control that will close the valve if there is no pressure up stream so that when the water comes back it will gradually open providing a smooth startup, the smooth startup will then also allow controlled venting of the air
Each valve will be 'downstream pressure-reducing upstream pressure-sustaining 106-PR-R' they can be backfitted to the existing models.

These valves are slow reacting, so startup will take time to change flow from full closed to wide open, you may want pressure tank(s) to help in pressure ballancing and smooting out the responses along with reducing water hammer.

If your flow rates are commonly low (2 gpm to 20 gpm) you may want to also add 3/4" or 1" bypass valves with the same functions to handle the small flows. They will also be more responsive at the low flow rates.

Hydrae