bluecollar84
Senior Member
- Location
- US
What is the best way to blow out a bunch of water in 4” pvc conduit 200 feet long ?
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
Water in conduit
- Thread starter bluecollar84
- Start date
- Status
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The blower output of a shop vac would probably work well enough, just not very fast.
If the geometry is such that there is a several foot pressure differential with standing water you might do better using suction instead. Where do you plan to dump the water that gets blown out?
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
How much is acceptable to remain in the conduit?
My thoughts are unless you have pretty high volume blower, you will only get so much out and then it will just blow over top of water standing in the bottom of the conduit. You may be able to get a blower to push water toward one end but not necessarily have enough umph to push vertically to get out of the ground (assuming an underground raceway that is reasonably level), but might be able to push one way with a blower and use a shop vac to pull water out the other end?
4 inch has plenty of room to insert hose for a transfer pump into it- even a 2 inch hose on a higher volume pump.
My thoughts are unless you have pretty high volume blower, you will only get so much out and then it will just blow over top of water standing in the bottom of the conduit. You may be able to get a blower to push water toward one end but not necessarily have enough umph to push vertically to get out of the ground (assuming an underground raceway that is reasonably level), but might be able to push one way with a blower and use a shop vac to pull water out the other end?
4 inch has plenty of room to insert hose for a transfer pump into it- even a 2 inch hose on a higher volume pump.
DrSparks
The Everlasting Know-it-all!
- Location
- Madison, WI, USA
- Occupation
- Master Electrician and General Contractor
Dzboyce
Senior Member
- Location
- Royal City, WA
- Occupation
- Washington 03 Electrician & plumber
You might try blowing a foam piston thru a couple of times after you have seen what just the vacuum cleaner does.
Another way way to look at it is; what air velocity will it take to clean the pipe? 4” conduit has a cross section of about 12 1/2 square inches. You need an air velocity of 3000-5000 feet per minute to clean a hole. That calculates to 250-400 cubic feet per minute of air. That will blow water, rocks, mice or whatever out of a conduit.
Another way way to look at it is; what air velocity will it take to clean the pipe? 4” conduit has a cross section of about 12 1/2 square inches. You need an air velocity of 3000-5000 feet per minute to clean a hole. That calculates to 250-400 cubic feet per minute of air. That will blow water, rocks, mice or whatever out of a conduit.
ptonsparky
Tom
- Occupation
- EC - retired
Lots of good unsafe ways. Make sure your pickup is no where close to the discharge end.
Wouldn’t hurt to warn the help.
Wouldn’t hurt to warn the help.
ptonsparky
Tom
- Occupation
- EC - retired
Run a fish tape thru then attach the piston and drag it back out quickly.
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Underground or above?
Mostly level or with risers?
The most working vacuum a generic shop vac will pull is usually less than maybe 18-20" water column, so if you have 24" risers to an underground conduit you're better off pulling it out with a suction pump and then dropping a vacuum hose in to slurp out what it can from the deep end. (I've seen vacs pull a static vacuum of >50", but any airflow deeply cuts that.)
Likewise, to push the water out, once there's less than 4" in the pipe you need to get enough airflow through to drag what's left along to the end (then vacuum it out) and enough pressure to get that flow past the leaks and general flow resistance of the pipe walls. Again, a generic shop vac probably won't do it.
I have heard of people pulling in a piece of rope or mule tape and then using a mandrill with a rubber disk at the front to push the water to one end for pumping out. Also helps with the mud.
Of course, if you have an un-pressurized underground conduit, it will eventually refill.
1 PSI = ~~28" water column
Water weighs about .58oz / cubic inch
If I have my math right, 1" of water in a 4" vertical EMT weighs about half a pound (8.5oz).
Mostly level or with risers?
The most working vacuum a generic shop vac will pull is usually less than maybe 18-20" water column, so if you have 24" risers to an underground conduit you're better off pulling it out with a suction pump and then dropping a vacuum hose in to slurp out what it can from the deep end. (I've seen vacs pull a static vacuum of >50", but any airflow deeply cuts that.)
Likewise, to push the water out, once there's less than 4" in the pipe you need to get enough airflow through to drag what's left along to the end (then vacuum it out) and enough pressure to get that flow past the leaks and general flow resistance of the pipe walls. Again, a generic shop vac probably won't do it.
I have heard of people pulling in a piece of rope or mule tape and then using a mandrill with a rubber disk at the front to push the water to one end for pumping out. Also helps with the mud.
Of course, if you have an un-pressurized underground conduit, it will eventually refill.
1 PSI = ~~28" water column
Water weighs about .58oz / cubic inch
If I have my math right, 1" of water in a 4" vertical EMT weighs about half a pound (8.5oz).
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
"Run, Forrest! Run!"
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
- Status