CL2 migration through poly tubing

[pmeloy]

Has anyone ever heard of or had problems with chlorine gas actually migrating though Polyethelene tubing? I've been using the stuff for years and never had a detector show any trace of CL2 in the gas room even when an exhaust fan is down for maintenance or replacement.

[Watermom]

Hi and welcome to the Pool Forum! Unfortunately, I can't answer this question but hopefully somebody will be along soon who can. Hope you enjoy being a part of the forum!

[PoolDoc]

Ok. Gotta ask.

Why would you even have chlorine gas IN polyethylene tubing. I was pretty sure, but I checked first: LDPE is not very resistant to wet chlorine gas. Your choices are more along the lines of Hastelloy C, PVDF or CPVC (under 100 deg F).

Anyhow, this isn't a question for the general forum -- I'm guessing I may be the ONLY one here who has experience with chlorine gas. So . . . I'm moving this thread to the China Shop.

[pmeloy]

Poly tubing is common as dirt on gas systems (vacuum). Depending on what type you buy it's good for one to four years. Go to home depot and you'll have to replace annually since it gets very brittle after 2-3 years. Buy the thicker version with more plasticizers from a commercial pool supplier and you'll be replacing every four years. Most of ours are such short runs that I use the better form and replace annually anyway. I'm already in there rebuilding regulators, injectors, and roto-meters so the added labour and expense is a drop in a bucket.

I'm asking this because another facility believes they have this problem with a CL2 gas line (the better quality stuff) filling an underground PVC pipe with gas. I'm thinking it's actually a different problem altogether but I don't deal with tubing that is essentially sealed into a small space.

[PoolDoc]

Optimizing chlorine gas feed systems for pools is NOT a topic for discussion here, outside this section!

Using PE on gas feed systems, even though it gets "very brittle" . . . is NOT something I'll ever recommend!

Buying Chinese made PE tubing from Lowes to use on chlorine gas feed systems is even worse. I've already -- personally and expensively -- had my belly FULL of problems and expense directly due to erratic product quality control on Chinese-made, Lowes-sold and (Watts branded) plumbing parts.

Pat, I'm not sure why you want to post this stuff here.

+ It's not relevant to residential pool use.
+ It does not reflect professional practice.
+ It's not safe.
+ It's not of any value (that I can see) to anyone here.

If your buds want to use PE with chlorine gas, and put that tubing in a confined space, that's on their heads. But if they want help from us on whether gas can migrate . . . nope, not going there. The ONLY recommendation from here is that they REMOVE the PE and replace it with something that's fully compatible with safe transport of chlorine gas, wet or dry. From the charts, it appears CPVC meets those requirements, and it's widely available.

It's the China Shop, so you may continue if you like. But, I can't imagine why you'd want to do so.

[pmeloy]

I don't know what charts you're looking at but every supplier of gas chlorinator equipment we've used supplies poly tubing (HDPE) with their kits. The wholesalers all have poly. Worksafe (like OSHA), and the health authorities are all fine with HDPE. Every municipality I've ever talked to that also uses gas uses HDPE save one; they use Kynar at over 10x the price that is still replaced every few years.

Why does the industry use HDPE if it's not the best on the charts? Probably because the more resistant products cost too much when compared to the material and labour required to periodically replace the less resistant products. These systems require frequent changing of tanks to the material must remain flexible and mechanically stable despite the stresses it's subjected to.

That's about all I can tell you. If you wish to consider anyone using poly as unprofessional that's your prerogative.

[PoolDoc]

I didn't see charts showing HDPE resistance, so I can't comment on that.

But, based on my experiences with Chinese plumbing product quality control, my working assumption would be that Chinese-made, Lowes-bought PE tubing *might* be HDPE (which might, or might not, be adequately resistant -- I don't know), or it might be LDPE (which is not sufficiently resistant) or might might be any other plastic that merely looked and felt like LDPE.

Using tubing that "becomes brittle" -- your words -- to transport chlorine gas is definitely on my "To-Don't-Do" list.

And, anyhow, in most of the areas I'm familiar with, chlorine gas use on pools is very actively discouraged (if not outlawed) by current regulations, so it's sort of a non-issue in those areas.