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topic 18103

Chlorine Leaching from CPVC


2002

Dear Sir or Madam,

I am interested in the hazards of chlorine leaching from CPVC. What conditions must exist for leaching to occur? Is the risk great enough to replace CPVC with another material?

Thank you very much.

Mary Woodruff
Iowa State University - Ames, Iowa


2002

Hi Mary,

What a weird question! Why CPVC ... why not ordinary PVC as that, too, is chlorinated, is it not?

This material is made in the form of pellets. These pellets go through a process ... extrusion, injection moulding, whatever ... during that process a small, ultra small whiff of chlorine may be given off.

But for the polymerized, i.e., final form, then this matrix will not break down easily. You should get absolutely ZERO leaching ... a slightly different matter occurs if you heat it up too much!

PVC and CPVC must be regarded as the factor by which all other plastics are judged ... and the only edge that CPVC has over PVC is temperature resistance. Both are super inert materials.

In short, zero hazard potential ... why, even copper is more hazardous ... which is why copper pipe is never used in fish rearing as it will kill hatchlings.

freeman newton portrait
Freeman Newton
White Rock, British Columbia, Canada

(It is our sad duty to
advise that Freeman passed away
April 21, 2012. R.I.P. old friend).



2004

I was wondering more about when Freeman Newton answered this question before he said there would be absolutely no leaching of chlorine a unless "slightly different matter occurs if you heat it up too much!" I was wondering what would occur and at what temperatures?

Adam Tabor
- Ames, Iowa, United States


2004

Hi Adam,

Re chlorine ... well, by itself I wouldn't recommend PVC nor CPVC ... but many people talk about chlorine when they mean chlorinated water ... where both of these materials excel.

Re temperature limitations? Ah, that depends, too, on the pressure, too, doesn't it. Assuming we're talking about Sch. 80, then the max. temp. for PVC/CPVC is 140 and 160 °F .... BUT .... in a dual laminate situation, you can go to MUCH higher temperatures and at higher pressures, too.

For a true chlorine liquid (or gas), I'd opt for a fluorocarbon or the PVDF material.

I assumed from Mary's request that she was talking about chlorinated water ... dammit, I really shouldn't have assumed anything, should I !

Freeman Newton
Freeman Newton
White Rock, British Columbia, Canada

December 3, 2008

I heard from a salesman at HACH that they don't recommend using PVC or CPVC with their auto-sampling equipment because industries testing for dissolved organics would have effluent samples that get false positives for organics due to leaching of the polyvinyl. He said that HACH opts to use pharmaceutical grade (flex?) hose in their auto-samplers instead to eliminate the leaching issue caused by their strongly acidic effluents....of course, consider that the source is a sales-rep, and that's why I decided to check online.

James Falk
Gateway CC Student - Scottsdale, Arizona, USA



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