Thinking of using PVC pipe for air?

This is where bits of wisdom will be stored, a frequently asked question section with answers.

Moderators: Harold_V, WJH

User avatar
SteveHGraham
Posts: 7739
Joined: Sat Jan 17, 2009 7:55 pm
Location: Florida

Re: Thinking of using PVC pipe for air?

Post by SteveHGraham » Sat Apr 01, 2017 9:07 pm

Someone explain the chlorine filter story.
Every hard-fried egg began life sunny-side up.

User avatar
NP317
Posts: 1915
Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon

Re: Thinking of using PVC pipe for air?

Post by NP317 » Sun Apr 02, 2017 10:18 am

I plumbed the compressed air in my new shop with commercially available air hoses. It was easy and works well.
The longest run is 50 ft. with 3/4" diameter hose.
~RN

tomjaksa
Posts: 22
Joined: Thu Mar 30, 2017 12:11 pm

Re: Thinking of using PVC pipe for air?

Post by tomjaksa » Tue Apr 04, 2017 12:38 pm

The chlorinator kept running without the 15kw filter pump there to provide flow. A by product of salt chlorination is Hydrogen gas.
It filled all the pipework with hydrogen gas!
They bypassed the safety switches to keep it running

And it was one of the top Universities in the country.

User avatar
SteveHGraham
Posts: 7739
Joined: Sat Jan 17, 2009 7:55 pm
Location: Florida

Re: Thinking of using PVC pipe for air?

Post by SteveHGraham » Tue Apr 04, 2017 3:32 pm

They bypassed the safety switches! And they weren't just using PVC for air...they were using it for an explosive gas! That's Darwin territory.

In fairness, I would imagine hydrogen would also blow iron pipe into smithereens.

Not surprised that it happened at a university. Common sense and the kind of sense that helps people get good grades are not always found together.
Every hard-fried egg began life sunny-side up.

User avatar
SteveM
Posts: 6890
Joined: Mon Jun 27, 2005 6:18 pm
Location: Connecticut

Re: Thinking of using PVC pipe for air?

Post by SteveM » Wed Apr 05, 2017 6:41 am

SteveHGraham wrote:In fairness, I would imagine hydrogen would also blow iron pipe into smithereens.
With a significantly higher mayhem potential!

Steve

John Hasler
Posts: 1271
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Thinking of using PVC pipe for air?

Post by John Hasler » Wed Apr 05, 2017 8:07 am

SteveHGraham wrote:They bypassed the safety switches! And they weren't just using PVC for air...they were using it for an explosive gas! That's Darwin territory.

In fairness, I would imagine hydrogen would also blow iron pipe into smithereens.

Not surprised that it happened at a university. Common sense and the kind of sense that helps people get good grades are not always found together.
You wouldn't want to use iron pipe around chlorine.

User avatar
SteveHGraham
Posts: 7739
Joined: Sat Jan 17, 2009 7:55 pm
Location: Florida

Re: Thinking of using PVC pipe for air?

Post by SteveHGraham » Wed Apr 05, 2017 9:29 am

So it's not just the hydrogen that goes through the pipes?
Every hard-fried egg began life sunny-side up.

User avatar
BigDumbDinosaur
Posts: 827
Joined: Tue Jun 28, 2011 9:19 pm
Location: Midwestern United States

Re: Thinking of using PVC pipe for air?

Post by BigDumbDinosaur » Wed Apr 05, 2017 9:56 pm

tomjaksa wrote:And it was one of the top Universities in the country.
There's quite a difference between being educated and having common sense.
—————————————————————————————————
I'm an old guy. What's your excuse? ☻

John Hasler
Posts: 1271
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Thinking of using PVC pipe for air?

Post by John Hasler » Thu Apr 06, 2017 9:59 am

SteveHGraham wrote:So it's not just the hydrogen that goes through the pipes?
I don't think hydrogen was supposed to be in the pipes at all. It isn't clear what was. If the pipes were supposed to be carrying chlorine it's obvious why they used plastic (bypassing the safeties and running the system without filters was still stupid, of course). I suspect that the system was properly engineered but improperly operated. I also doubt that any of the university faculty were involved (or even knew about it). Professors don't usually do plumbing.

tomjaksa
Posts: 22
Joined: Thu Mar 30, 2017 12:11 pm

Re: Thinking of using PVC pipe for air?

Post by tomjaksa » Sat Apr 08, 2017 5:27 am

The chlorinator makes chlorine from salt in the water. It runs plumbed in the return line of the filter plant. The small amounts of hydrogen are carried away with the water. The main filter pump stopped, water was not being carried away. They bypassed the flow sensor. It was like that for about seven days. The hydrogen gas had nowhere to go,
As for the faculty i do not know..... The maintenance staff was warned not to do it. The last thing i said to them in the reply letter was for them to ask on of the "proffies" why they should not do it.
Luckily i had a copy of the letter to show them that i said they must not do it When it came to paying for an new filter plant.
And all that to save some bucks on granular chlorine.

User avatar
SteveHGraham
Posts: 7739
Joined: Sat Jan 17, 2009 7:55 pm
Location: Florida

Re: Thinking of using PVC pipe for air?

Post by SteveHGraham » Sat Apr 08, 2017 10:42 am

Now I know what you're talking about. When I was a kid, my dad had a gadget called a Genie-Chlor. It was an electrolysis machine that turned salt into chlorine gas. It sat next to the pool pump. It was supposed to save us the hassle of adding chlorine tablets to the water.

It turned out to be pretty worthless. The seller kept coming to the house and putting bags of salt in the pool, but it never lived up to the hype. I would guess the problem was that chlorine gas evaporated and left the pool. To make it work, you would need a constant supply of chlorine salts that could be broken up to free chlorine.

PVC was not a problem for this machine. The pipes were was carrying chlorinated water, which works fine with PVC, and it never got the opportunity to fill the plumbing with hydrogen.

The Internet says PVC works fine carrying chlorine gas below atmospheric pressure, but that pressurized chlorine will make it porous.
Every hard-fried egg began life sunny-side up.

John Hasler
Posts: 1271
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Thinking of using PVC pipe for air?

Post by John Hasler » Sat Apr 08, 2017 7:22 pm

> I would guess the problem was that chlorine gas evaporated and left the pool.

It would be used up as it reacted with organics in the pool as well (but that's what it is for).

> To make it work, you would need a constant supply of chlorine salts...

Sodium chloride: table salt. Water-softener salt or feed salt from the feed store would work fine.

My high school had an indoor pool that was heavily overused. To keep the E. coli count within legal limits without changing the water as often as they should have they chlorinated the hell out of it. Of course they also were too cheap to adequately ventilate the pool so every student got to breath chlorine gas for about half an hour every week until they fulfilled their swimming requirement.

Post Reply