• We will be performing upgrades on the forums and server over the weekend. The forums may be unavailable multiple times for up to an hour each. Thank you for your patience and understanding as we work to make the forums even better.

Dewatering Conduit

Merry Christmas
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
Dennis Alwon said:
I installed a 2" conduit about 150' . A few months later we went back and pulled a line thru--- bone dry. It was the first time I used pvc primer and then glue.
Click to expand...

Yeah you certainly can keep the water out if you do a more careful job, and primer I think helps. I have always said there are times when this is important, like when you have a conduit sloping down hill and into a basement.
 
H

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
electrofelon said:
Yeah you certainly can keep the water out if you do a more careful job, and primer I think helps. I have always said there are times when this is important, like when you have a conduit sloping down hill and into a basement.
Click to expand...
Both ends must be sealed to keep out condensate.
Otherwise there will be some water in a pipe glued tight
 
H

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
electrofelon said:
Sure but the issue I am talking about is when a conduit slopes downhill through a wet area into a basement, and has joints that are not watertight. I have seen a continuous stream that is very hard to stop.
Click to expand...
Oh yes. When we leave a transformer or a vault and go downhill to a house we put everything in conduit. We have had water come into the meter bases go into the breaker panels and leaking inside the house. For those we will put a hole in the backside of the elbow where it turns up to the meter base.
 
TwoBlocked

TwoBlocked

Senior Member
Location
Bradford County, PA
Occupation
Industrial Electrician
Soooo, There were four 2" stub ups that are supposedly making up two underground 2" PVC conduits. One, I could see some water in. One at a time, I blew into them with a 20 gal shop vac. Could tell a large amount of air was going in from the suction on the shop vac, BUT NO AIR COMING OUT OF ANY OF THE CONDUITS!!! So I then tried suction on each of them, little or no air coming out and no suction on any of the conduits. I Did get a little water on 3 of the conduits, less than a gallon all together.

My guess is the conduits are broken underground and there are pools of water. Dry fitted caps on the conduits and marked "NFG."

I do wonder why I could blow air, but not suck...
 
TwoBlocked

TwoBlocked

Senior Member
Location
Bradford County, PA
Occupation
Industrial Electrician
electrofelon said:
can you try putting a fish tape in to confirm if its broken? I recall trying to get water out of conduits with a shop vac and not having much luck.
Click to expand...
Wasn't going to risk losing a fish tape. Besides, They don't need it now, just wanted it cleared out for future use. It is designated for temporary instrumentation so they will probably go wireless if needed.
 
S

SceneryDriver

Senior Member
Location
NJ
Occupation
Electrical and Automation Designer
Got a plumber friend with a camera snake? That could tell you a lot.


SceneryDriver
 
S

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
I am with the tow behind air compressor option. You don't really need the sealing rig shown but it is a nice addition. A couple rags will do the trick. Make sure to have your apprentice guard the other end. (just kidding) make sure no one is within 20 feet of the other need of the conduit.
Barring that, using a vacuum cleaner you need to "rock the boat" not plug and end and try to pop it. Rock the boat is suck, remove, suck remove, in a rhythm like 1,2,3...1,2,3... the water will start rocking back and forth.
 
Knuckle Dragger

Knuckle Dragger

Master Electrician Electrical Contractor 01752
Location
Marlborough, Massachusetts USA
Occupation
Electrical Contractor
TwoBlocked said:
Got a small job coming up. Part of it is to "dewater" some underground 2" conduit that got flooded. Nothing is in them, just for future use. No caps had been installed on the stub ups, so the flood waters was free to enter, and they are full.

Haven't done this before. Figure to start with blowing them out with a shop vac. Once most of the water is out, keep blowing into one end while holding a hand over the other to build up pressure and then release it to "burp" more water out.

Here's my question: Should I stop after burping, or should I try to pull some kind of piston through to get all the water out? I'm concerned with getting it stuck if there is a lot of mud, or if the conduit broken under ground. I'm sure some of you fine folks have good advice for me.
Click to expand...
I know I'm late to the discussion. If it's a lot of water I would pull a mouse (some kind of piston) threw then plow or suck. The water could be too heavy blow with a shop vac ( maybe ren a large compressor).
Goodluck!
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
Yeah I am just remembering an electrician friend of mine telling me how he had to rent one of those big boy not screwing around tow behind air compressors to blow a line through. IT was a big pipe filled with water and I guess neither the shop vac nor the homeowner harry air compressor would do the job.
 
TwoBlocked

TwoBlocked

Senior Member
Location
Bradford County, PA
Occupation
Industrial Electrician
electrofelon said:
Yeah I am just remembering an electrician friend of mine telling me how he had to rent one of those big boy not screwing around tow behind air compressors to blow a line through. IT was a big pipe filled with water and I guess neither the shop vac nor the homeowner harry air compressor would do the job.
Click to expand...
Yeah, but air blew into the conduit very well without any coming out of another conduit. Then when sucking, it would be almost a vacuum, drawing only a little water.
 
N

neault

Member
Location
MA
Occupation
Retired Engineer
Velocity moves the water. You can plug the shop vac with your hand, and may not be able to push through. Low pressure high volume will be best. Look to the irrigation contractors that blow out the lines at the end of season.
 
R

retirede

Senior Member
Location
Illinois
Hv&Lv said:
I don't think irrigation is pushing 2,000lbs of water
Click to expand...

It doesn’t matter. The amount of pressure required to expel the water is largely determined by the burial depth. For very long runs, friction will come into play once it starts moving.

If a pipe is buried 3’, applying a pressure greater than 36” WC will start pushing the water out. The higher the pressure, the faster, as long as the air source can supply the required flow.
 
You must log in or register to reply here.
Top