Automatic Draining of Pipe above a Check Valve

[rangercap]

Does anyone know of a relief valve that has the ability to drain the portion of pipe above the check valve?

I have a client who wishes to do this. His idea is when the check valve closes, a smaller separate valve will open (automatically) and release the water contained in the pipeline above. An AV release is already placed in the system.

I spec'd a 2" bronze ball valve on a tee above the check valve that would enable manual draining of the line. My client wishes to this automatically, but i can't see how an automatic relief valve can distinguish between a line flowing under pressure and a line containing a static volume of water.

Thanks

Brian

 

[Pumpsonly]

You can install a small line with a check valve in the reverse direction across the main check valve.When the pump is pumping, the pressure will keep the small CV closed. When the pump stop the small check valve will allow water above it to drain back to the suction tank.

 

[bimr]

There are a number of companies that make hydraulically operated valves that can do this function.

One of these companies is Cla-val. They make an valve with an unloading function. They have a few valve arrangement that you can use, depending on your application. A few examples:

The Model 93-01/693-01 can be installed in a distribution line where there is a need to close the unloading valve on the starting of a pump. The solenoid control is activated on pump start-up and closes the valve.

The Model 136-AU Battery-Operated Programmable Control Valve is ideal for automating distribution system flushing applications. Model 136-AU applications requiring remote, stand alone valve opening and closing on a predetermined schedule include night-time tank filling, service line limiting time of use, automatic line strainer flushing, etc.

I am not sure of the exact details of what you you are trying to accomplish. But Cal-val has the equipment that you need. Give them a call for specific details.

http://67.199.35.174/pdfs/CV_Control_Solutions_Catalog.pdf

 

[rangercap]

Thanks, bimr. I'll check them out.

BTW, we are moving fresh water from streams to impoundments for shale gas development and will have some sections buried and other above ground. Sections above ground are going to be drained in the winter, but the client wishes to do this automatically. These valves will most likes be exposed to extreme temperatures for extended periods of time, so I'm looking for something fool-proof (if there is such a thing).

Brian

 

[bimr]

For devices above grade, you will have to have some type of heated insulated enclosure.

You may need to blow the lines out as well. I doubt all of the fluid will drain by gravity.

 

[BigInch]

Reverse check? Why have a check valve if you are going to put in a small reverse check valve. You only need the main check valve when the pump is not running, so installing a smaller reverse on a bypass defeats the whole purpose of having a main check valve.

Put a solenoid on the drain valve with a temperature control. When the temp gets to zero F, open.

We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer

 

[SteveWag]

I’ve done a number of jobs where I simply drilled a hole, or tapped the bottom of the pipe and added a small pipe and directed it to a drain. When the pump turned on, water flowed out these holes/drains and was wasted. When the pump turned off, the system drained. It works well when hundreds of GPM are being pumped and the material is just water. I have also but a one-eight hole just above the check valve on a submersible well pump with the intention of draining the line to prevent freezing. Just be careful of erosion of the side of the well and the air entrained in the system when drained.
Steve

 

[Pumpsonly]

The small CV in the reverse flow direction on the By-pass is to allow draining of the water above the main CV automatically and is FOOL PROOF.
Using a solenoid valve with temp. sensing means extra wiring and instrumentation.

Drilling a hole in the CV as proposed by SteveWag is even more simpler solution provided a simple conventional type CV is used. But not on those proposed by bimr.

 

[SteveWag]

We have a few of these in PA at drilling sites. Rather than trucking water, as is done at most sites, if water is near it is pumped, especially if the water main can be installed along with the gas transmission line. I have drilled a hole at the low spots, beneath grade, and put a load of stone I as backfill. This way the pipe drains to the low spot(s) and is empty during static, freezing times. Of course you don’t know if the hole(s) become clogged, but these are less labor intensive than automatic schemes and more easily understood by laymen.
Steve

 

[rangercap]

Makes sense, Steve. I'm likely to stay away from any automatic valves, just because of the remote locations, and maintanence headaches.

Where are you working PA? We have marcellus work in Susuqehanna and Clearfield counties right now.

Brian

 

[SteveWag]

We have offices in Hollidaysburg and Towanda
Steve

 

[SteveWag]

When I do one of these I first look at the expected life. For a typical well development site I just drill some holes in the pipe. If the pipe is PVC, they last for years and are quick and dirty. If steel pipe I sometimes put a very short stainless nipple in a tapped hole. If you’re welding, just a one inch long piece of plain end pipe. If it is to be a long term job, I sometimes put valves on the tap and or daylight the drain end. Daylighting brings freezing. A small underground valve can be operated with a steel rod and by listening to the rod as the valve is operating I can tell if the drain is clogged or flowing. The best drains are underground and drain to a rock filled sump, no valve and no freezing.

As to sizing, I have a table that I found years ago (see link). It’s an AWWA “Leak Loss” table showing loss (flow) at various diameters and pressures. If your pumping 4-500 GPM at 100 PSI, then a 3/16-inch hole “leaks” about 8 GPM, or about2% of the flow.
Steve

 

[PEDARRIN2]

Sprinkler contractors install these all the time to drain the piping upstream of the check valve which is connected to the outside fire department connection.

Since these connections are sometimes above grade, the piping between the check valve and the connection needs to be drained.

Not sure if this is what you want, but you can look on

http://www.vikinggroupinc.com/en/technical/233/241

for information.