# schedule 80 to 40



## d78coots (Mar 30, 2009)

I know this question is downright dangerous, but please bear in mind I am a simple commercial plumber. Just got a job, building is completely plastic. Now I am a cast/copper Guy because all the old schools say its manly. Point I am trying to make is, I've never used cpvc. 

Need to tie into a 4" cpvc sch80 water main, but it'll transition to a 1" cpvc sch40. Do I need a special transition fitting or is sch80 and sch40 interchangeable in regards to PVF?


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## Widdershins (Feb 5, 2011)

d78coots said:


> I know this question is downright dangerous, but please bear in mind I am a simple commercial plumber. Just got a job, building is completely plastic. Now I am a cast/copper Guy because all the old schools say its manly. Point I am trying to make is, I've never used cpvc.
> 
> Need to tie into a 4" cpvc sch80 water main, but it'll transition to a 1" cpvc sch40. Do I need a special transition fitting or is sch80 and sch40 interchangeable in regards to PVF?


 Somebody finally stumped me.

In my defense -- I wouldn't use cpvc for anything that might ever conceivably be put under pressure.


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## rocksteady (Oct 8, 2008)

I've never worked with sch. 80 cpvc. I do know that the un-chlorinated pvc has the same o.d. whether sch. 40 or 80. I'm thinking you're fine changing from 80 to 40 without any special fittings.








Paul


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## d78coots (Mar 30, 2009)

Widdershins said:


> Somebody finally stumped me.
> 
> In my defense -- I wouldn't use cpvc for anything that might ever conceivably be put under pressure.


I totally agree with you. But everything in this seven story is plastic. I couldn't believe it. The 4" says its rated 320 psi WP @ 73F.


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## d78coots (Mar 30, 2009)

d78coots said:


> I totally agree with you. But everything in this seven story is plastic. I couldn't believe it. The 4" says its rated 320 psi WP @ 73F.


If you know what I mean.


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## Protech (Sep 22, 2008)

No transition fitting should be needed.

Are you sure it's 1" sch 40 and not 1" CTS? If that's the case, then YES you will need a transition bushing.



d78coots said:


> I know this question is downright dangerous, but please bear in mind I am a simple commercial plumber. Just got a job, building is completely plastic. Now I am a cast/copper Guy because all the old schools say its manly. Point I am trying to make is, I've never used cpvc.
> 
> Need to tie into a 4" cpvc sch80 water main, but it'll transition to a 1" cpvc sch40. Do I need a special transition fitting or is sch80 and sch40 interchangeable in regards to PVF?


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## U666A (Dec 11, 2010)

Schedule changes inside diameter always, never outside diameter. Period

Sent from my iPhone using PlumbingZone


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## d78coots (Mar 30, 2009)

Protech said:


> No transition fitting should be needed.
> 
> Are you sure it's 1" sch 40 and not 1" CTS? If that's the case, then YES you will need a transition bushing.


Couldn't CTS be sch40? I assume all PVF will be CTS, where the OD is 1/8 bigger than ID


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## Widdershins (Feb 5, 2011)

U.A.til.I.die said:


> Schedule changes inside diameter always, never outside diameter. Period
> 
> Sent from my iPhone using PlumbingZone



Good call, Rain Man.


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## d78coots (Mar 30, 2009)

U.A.til.I.die said:


> Schedule changes inside diameter always, never outside diameter. Period
> 
> Sent from my iPhone using PlumbingZone


Did not know that. Thanks! So the answer is yes, they can be joined together, depending on whether both components are CTS or sized for steel.


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