PVC conduit used for pressure pipe?

[mcbane]

I plan to run PVC pipe up to rooftop sprinklers. I would use ordinary SCH40 except that is not UV resistant. I know that gray SCH40 PVC conduit is UV resistant but have no idea whether it is good for 60 psi operating pressure. Does anyone know whether that is a workable solution?

I want to avoid running copper due to the soldering work and the $$$ for materials.

 

[nadogail]

Why not use CPVC or Schedule 80 PVC?

 

[mcbane]

Why not use CPVC or Schedule 80 PVC?

Both of those plastics are special order in my area. I guess I should price it out vs copper.

 

[fitter30]

They don't make 90° ells (close radiance and with bells on each end to accept pipe) and tees in conduit. Conduit isn't tested for pressure.

Heritage Plastics has PVC conduit, fittings, accessories

Heritage Plastics is an American manufacturer of PVC conduit, fittings, and pipe for the electrical, irrigation, municipal and plumbing markets.

www.google.com

 

[LOW1]

Can you run pex in the enclosed area and when exposed to sun use copper with shark bite fittings?

But all copper with sweat fittings can’t be too much more expensive. How long is the total length that you need? And soldering joints is actually kind of fun,

 

[HoosierBuddy]

You shouldn't use conduit for pressure.

Understanding the Differences Between Electrical and Plumbing PVC

Plumbing and electrical PVC piping have a number of key differences, including their color, wall thickness, and, most importantly, their applications.

www.commercial-industrial-supply.com

 

[rlitman]

I would be wary of PVC used for this. I've seen black poly installs that when left to sit in the sun and heat under pressure blow out. While PVC is a little more heat resistant, without flowing water, it can get heated in the sun beyond its service limits.

CPVC is a better answer, since it can handle hot water. An alternative is to use white PVC and paint it white. The white paint should not only block the harmful UV, but also keep the pipe reasonably cool.

 

[karoc]

Why not rigid pipe, where I work rigid pipe is used for drains on roof for ac units which is exposed to sun all day, every day. Do it once never have to do it again, well maybe in 40 yrs. Yea its a pain run, but most HD sells that pipe in different lengths.

 

[kbs2244]

sch40 will handle the pressure
but I would do it karoc's way
conduit is not designed for any pressure
it is designed to protect wires that is all

 

[John in OH]

PVC conduit should NEVER be used in pressure service. It was never intended for such service. Bad practice.
If you want to use PVC, use PVC piping or CPVC, NOT conduit.

 

[rayra]

If it isn't under constant pressure, just use Sched40 PVC and paint it. It'll work fine.
Where will the valving / controls be?

 

[bigdav160]

I've used gray PVC conduit for pressurized water pipe on my farm for years. I've never had one issue with it.

YMMV

 

[mike93lx]

Pvc is UV resistant. The outside will get weathered, but the pipe will be structurally sound for a long, long time.

Many studies have been done on this and all the exposed pool plumbing supports it too

 

[andyvh1959]

Could also use nylon air brake tubing, made for constant duty air pressure, UV stable, Ozone stable. Rated to 150 psi constant duty and 500 psi burst pressure. Can use standard compression fittings available at near any hardware store/Home Depot/Lowes/Menards. Can also use commonly available push to connect fittings. Comes in many colors; black, red, green, blue. Many sizes from 1/4" up to 1".

 

[AndyL]

As mentioned above - PVC isn't rated but it's rate of degredation is pretty slow.

And of course - a couple cans of krylon can make it look less awful + add some uv protection

 

[Walkers]

Pvc is UV resistant. The outside will get weathered, but the pipe will be structurally sound for a long, long time.

Many studies have been done on this and all the exposed pool plumbing supports it too

Show me one study. PVC (the white stuff) is not UV resistant, and after it sits it the sun (usually less than a year) it gets brown on the outside. At that point it is incredibly fragile. That is why they generally paint the pipe when exposed to the sun.

 

[Toolfool]

Rooftop sprinklers for fire protection ? Invest the money in copper.

 

[mike93lx]

Show me one study. PVC (the white stuff) is not UV resistant, and after it sits it the sun (usually less than a year) it gets brown on the outside. At that point it is incredibly fragile. That is why they generally paint the pipe when exposed to the sun.

Is PVC and CPVC pipe UV resistant? | U.S. Plastic Corp.

Weatherability of PVC Pipe

www.usplastic.com

Yes UV has an impact, on the outside of the pipe. Paint can help mitigate that, but UV doesn't ruin pipe like you seem to indicate

 

[mcbane]

Rooftop sprinklers for fire protection ? Invest the money in copper.

Only looking at plastic for a temporary fix. I need to replace siding in the near term and want to have sprinklers until that can be done. Will eventually install copper.

 

[pima67]

When I used sch 40 for a low pressure (25 lbs) irrigation system, I painted it to match the house (tan color). That was 10 or so years ago. No problems. It is on the east side so it has morning to noon sun exposure. It runs up and over the garage door and then down to the ground. I couldn't put it in the existing sleeve under the apron because the original black pipe was jambed in the sleeve and I could not get it out to make room for the pvc

 

[Walkers]

Is PVC and CPVC pipe UV resistant? | U.S. Plastic Corp.

Weatherability of PVC Pipe

www.usplastic.com

Yes UV has an impact, on the outside of the pipe. Paint can help mitigate that, but UV doesn't ruin pipe like you seem to indicate

Your study is say the the UV hardly harms it, however they say that is should be painted. I notice that it was done by the plastics industry, and they seem to downplay he amount and time for degradation. The study seems to be talking about a 1 year exposure time (I also read several other studies, also by plastics companies).
I don’t see a great deal of exposure damage in a year, but 5 year old PVC, here in AZ with one of the higher UV exposure areas on the studies charts, makes to pipe so fragile that it doesn’t take much to break it. Also be aware that we are not talking about schedule 80, or CPVC, just ordinary schedule 40 that you get at the big box stores.
If you want to run PVC above grade, have at it. Just don’t be surprised when it breaks.

 

[rayra]

Is PVC and CPVC pipe UV resistant? | U.S. Plastic Corp.

Weatherability of PVC Pipe

www.usplastic.com

Yes UV has an impact, on the outside of the pipe. Paint can help mitigate that, but UV doesn't ruin pipe like you seem to indicate

That just tells me you've never had to actually deal with an exposed old PVC pipe.
UV and solar insolation very quickly destroy exposed Sched20 PVC, making it very fragile and prone to breakage.
Sched40 buys you a decade. Painting the pipe goes a long way towards preserving it.
Sched80 and paint, you'll never have to worry about it again.

3/4 in. x 10 ft. Copper Type L Hard Temper Straight Pipe is $42 right now.

3/4 in. x 10 ft. PVC Schedule 40 Plain-End Pipe is $6.50, or 15% of what copper costs.

 

[Dogmeat]

I have a 125 psi compressor, and I've used 1" Sched. 80 pvc pipe, which is rated for 480 psi, which is MORE than
adequate for my compressor. My compressor is outside of my enclosed, insulated work/party area, and I run
this overhead and down to the work/party area...been that way for over 10 years, and it works GR8! Actually,
that extra distance also works like an extended accumulator, increasing the volume of compressed air that is
in addition to the compressor tank as well! I used 45 degree fittings instead of 90 degree fittings at all
bend areas to allow the air to flow easier!

 

[mike93lx]

I have a 125 psi compressor, and I've used 1" Sched. 80 pvc pipe, which is rated for 480 psi, which is MORE than
adequate for my compressor. My compressor is outside of my enclosed, insulated work/party area, and I run
this overhead and down to the work/party area...been that way for over 10 years, and it works GR8! Actually,
that extra distance also works like an extended accumulator, increasing the volume of compressed air that is
in addition to the compressor tank as well!

We have a winner!

 

[Dogmeat]

WOW mike931x, that was a FAST response....thank YOU!

 

[mike93lx]

WOW mike931x, that was a FAST response....thank YOU!

I am 100% sarcastic. Pvc for air is a terrible idea.

If it was a workplace, you would get an OSHA citation. Hopefully it never pops, because if it does, it will be incredibly dangerous

 

[Stuart in MN]

I have a 125 psi compressor, and I've used 1" Sched. 80 pvc pipe

The original poster is talking about water under pressure for a sprinkler system, not compressed air. Totally separate things.

 

[Dogmeat]

Well, Stuart.....EXCUSE Me for not relating to water vs. air....hell, pressure IS pressure...I was simply pointing out that
heavy wall PVC CAN be used for a LOT o' pressure applications.....U think I don't know they are TOTALLY SEPARATE THINGS??!!

 

[mike93lx]

Well, Stuart.....EXCUSE Me for not relating to water vs. air....hell, pressure IS pressure...I was simply pointing out that
heavy wall PVC CAN be used for a LOT o' pressure applications.....U think I don't know they are TOTALLY SEPARATE THINGS??!!

Pressure is not pressure. Storing compressed air and water under pressure are dramatically different things

 

[Dogmeat]

I am 100% sarcastic. Pvc for air is a terrible idea.

If it was a workplace, you would get an OSHA citation. Hopefully it never pops, because if it does, it will be incredibly dangerous

WOW Mike....in 1 post U AGREE, and with this post U totally disagree with your original "like" post....WTF???
This is NOT a fkn workplace, and at 120 psi, which is WELL under the 480 psi rated mat'l, it would never burst...and, IF it
did, coming out of a 1" PVC Sched. 80, it would NOT be "Incredibly dangerous".....whatever!!

 

[mike93lx]

WOW Mike....in 1 post U AGREE, and with this post U totally disagree with your original "like" post....WTF???
This is NOT a fkn workplace, and at 120 psi, which is WELL under the 480 psi rated mat'l, it would never burst...and, IF it
did, coming out of a 1" PVC Sched. 80, it would NOT be "Incredibly dangerous".....whatever!!

There is no contradiction in my posts. Pvc is not safe for air. Will it always fail? Nope. But when it does, it is bad

 

[Dogmeat]

I'm done wif this "mildly entertaining" thread...

 

[Stuart in MN]

The reason for not using PVC for compressed air is that gases are compressible and liquids are not, and PVC is not ductile like metal.

If you have a pipe containing a liquid under pressure and it springs a leak, the liquid doesn't expand - it just squirts out. On the other hand if you have a pipe containing a gas under pressure and it springs a leak, the gas expands rapidly as it comes out of the leak. In a metal pipe the material around the leak will bend, but in a PVC pipe the rapidly expanding gas can shatter pieces and shoot them out explosively like shrapnel. There are many documented cases, and several people here on the board (including me) have seen it happen in person (and yes, sharp shards of broken PVC were stuck in the walls around the pipe that failed.) If you look at the technical specifications from any PVC pipe manufacturer, they will state specifically that their products are designed for use with liquids only.

 

[cvairwerks]

From Boyles Law and making the assumption that the temp of the gas stays the same, as well as the number of molecules, P1V1=P2V2.

From there, a 100 gallon tank of air, held at 120 psig, when released to atmospheric pressure, will expand to a volume of approximately 12,000 gallons of air at under 1 psig. Lots of other stuff happens and comes into the exact calculations, but the numbers are close enough for non lab work...

 

[Toolfool]

I can't believe anyone can be on GJ for five years and NOT have seen all the PVC airline conversations.

 

[cvairwerks]

I can't believe anyone can be on GJ for five years and NOT have seen all the PVC airline conversations.

That or understand the basic information in the ratings listed on the pipe.

 

[nadogail]

For what it may be worth the decontamination piping on US Navy ships was PVC; I say was because I retired from the Navy in 1981. The Water Wash Down System was a dry system, that is water was only put into the pipes when the need for washing the exterior of a ship was determined to be necessary. Those plastic pipes which were covered with paint seemed to tolerate exposure to the weather quite well.

An externally valved sprinkler system built with dry pipes should not have a lot of problems.

This assumes that the fire sprinklers will be a dry system and valve controlled.

 

[BombShelter]

Dogmeat, please do not use PVC for air lines, when it blows it throws shrapnal pieces at a high velocity around the room. It's never the installer of the system that gets hurt, its the little kid watching his dad. They make Duraplus ABS Piping for these applications, when it blows it's more like bubble gum popping.

Going back to my PVC pipe days years ago, I think they mostly used latex paints for outdoor applications and not something like Krylon which might have a chemical reaction with the PVC, check with somebody like Georg Fischer for their recommendations, they make some of the best PVC pipe. https://www.gfps.com/en-us.html

Unfortunately to meet code I think you need the orange-fire rated plastic pipe system? But then I found this website with failures due to other construction materials.

Fire Sprinkler Piping — Plastic Pipe Experts

CPVC Fire Sprinkler Piping Life-saving systems can cause more harm than good.

www.plasticpipefailure.com