Pressure release for sediment jetting system 1

[deccantrap]

Hello Y'all!

I am working on a retrofit of a water jetting system which consists of a 30 HP pump pumping water through a 6" PVC pipe which is sealed at the other end, but has 1/8" holes spaced 6" apart. The purpose of the system is to "jet out" water from the 1/8" holes to keep sediment from settling in a river intake.

The system failed in operation in the past because in the non-pumping season, the 1/8" holes fill with biologic growth and debris, thus causing undue pressure in the system and tripping of the pump.

The idea is to install a "pressure valve" or "relief valve" which would allow the egress of excess pressure. This valve needs to stick above the water, so the operator can get a visual clue that there is excess pressure.

Does anyone has any ideas what kind of valve would be suitable? This is my first experience with pressure/relief valves.

Thanks.

D.T

 

[coloeng]

deccantrap,

It sounds like what you are looking for is a surge relief valve. They are typically setup so that if the pressure on the line exceeds their setting they will open and discharge. The discharge could be set above the water surface so that the operator would see that it has opened. Clavalve is one manufacturer, I am sure there are others.

HTH

 

[bimr]

The valve that you need is a pressure relief valve. These open on high pressure and discharge to atmosphere. The valves will automatically close when the pressure drops. Cla Val makes one, Farris Engineering also makes one:

http://www.cla-val.com/pdfs/E-750-01.pdf

 

[Artisi]

Fitting the relief valve will overcome the problem of the pump operating against a high discharge pressure - but my concern would be to address to blocking of the holes - why not set-up a routine run of the pump each week / month or what ever is needed and remove the problem completely.

 

[dnsalyer]

If the pressure is not too high, you could also install a standpipe. If you know the headloss across the orifice, make the standpipe height equal to something greater than that. When water is coming out of the standpipe, you have your answer.

P.S. Put a gooseneck and bug screen at the top of the standpipe.

 

[deccantrap]

Thank you all for your tips. I checked out the suggested manufacturers and found some appropriate valves. But let me pose another question:

The valves I found based on the suggestions have cast-iron or steel parts in them. The river intake being at the bed of the river, the valve will periodically be submerged in high-flood events. Attempting to raise it higher than the high-flood level is not practical since it will involve a standpipe more than 40' high. I would like to use a valve which can operate under submergence (i.e., it has stainless steel parts).

Any ideas?

 

[dnsalyer]

You could look at a plastic relief valve, such as a Plast-o-matic RVT (only goes to 2").

http://www.plastomatic.com/rvt.html

There are all-stainless relief valves available from a number of mfrs. A good company to talk to is North American Safety Valve.

http://nasvi.com/nasvcat.htm.

They rep a number of brands, including Farris and they have competitive prices.

If the relief valve is sized for full flow, it will be large and expensive. I don't know what flow rate you have here, but if the 6" pipe is any indication, you are talking about an expensive relief valve, probably in excess of $3,000.

I think you'll find that the same problems you're having with plugged orifices will show up in a submerged relief valve as well, regardless of material.

If you're just trying to protect the pump from dead-headng, you could install the relief valve near the pump discharge or install a pressure switch.

 

[bimr]

There is no reason that the relief valve should be in the river. Put the valve in the pump discharge line close to the pump location.

 

[BigInch]

Pressure gage on the pipe with a green band and a red line painted on the glass.

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[cvg]

gold star for biginch - the key is to shut off the pump when it runs in the red. If you want to reduce excess pressure, then reduce the flow by throttling the pump so that pressure stays in the green range. but the bigger problem is how to keep it from plugging in the first place.

 

[BigInch]

Thanks.

I think Artisi already mentioned that solution. Run it for a few minutes on a regular basis. Probably will have other benefits as well.

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[bimr]

It should be somewhat obvious that the system will plug since it has 1/8" diameter holes.

Do you have some type of strainer on the pump suction or intake?

 

[sewerratt]

IS this a homemade system or something available on the market? I've been looking for a system for a similar sediment problem. SOunds like what I was looking for. Any company info available on the jetting system would be appreciated.

thanks