PVC pipe sizes - what the ???


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Old 12-03-14, 03:31 AM
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PVC pipe sizes - what the ???

I bought some Schedule 40 PVC and fittings at Home Depot. They're all labelled as 1/2" ASTM D1785, but it's larger than expected. I took its measurements with a caliper, and get an OD of over 1", ID about 0.84... From all the charts I can find this appears to match the specs for 3/4" nominal. Am I missing something here?
 
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Old 12-03-14, 07:24 AM
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Looks like someone stuck a CPVC fitting into the wrong place.

CPVC Pipe Schedule 40 Dimensions
 
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Old 12-03-14, 08:24 AM
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Can you clarify? The old pipe that this was supposed to replace is CPVC, but that also marked as 1/2". Doesn't D1785 cover both types and specify the same dimensions?
 
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Old 12-03-14, 09:23 AM
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They're all labelled as 1/2" ASTM D1785, but it's larger than expected.
Iím no plumber but if the above is stamped on the pipe then to me that is a real head scratcher. I donít think there is any way thatís a half inch PVC or CPVC pipe if you measure its OD to be greater than an inch.

1/2 inch Schedule 40 CPVC, OD = 0.840
1/2 inch CPVC-CTS, OD=0.625
1/2 inch Schedule 40 PVC, OD=0.840
 
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Old 12-03-14, 11:13 AM
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Hold on a sec....what did you actually measure? The pipe or fittings? Wasn't clear.

I just checked a section of 3/4 pipe and it matches your readings for the stuff labeled 1/2.

They could just have a badly marked shipment...which someone should have caught and pulled.
 
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Old 12-03-14, 11:21 AM
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This whole situation is... less than nominal.
 
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Old 12-03-14, 11:21 AM
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I bought some Schedule 40 PVC and fittings at Home Depot.
And...

The old pipe that this was supposed to replace is CPVC, but that also marked as 1/2".
PVC and CPVC are two different materials, they are NOT interchangeable. Their nominal sizes are different as well.

If you have CPVC that needs to be replaced you CANNOT use PVC for the replacement.
 
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Old 12-04-14, 08:35 AM
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Ok, figured it out. First, the PVC is fine re: the labeled size - I guess I just confused myself.

As for the size difference, it seems those specs are not mandated by Schedule 40 or ASTM D1785 (on a side note, CPVC has now been split off into ASTM F441) but rather by which sizing standard it's made to, in my case IPS (iron pipe size) for the PVC and CTS (copper tubing size) for the CPVC.

As for interchangeability, this is for the condensate drain on an HE furnace. The manufacturer states either is acceptable, it's just a matter of getting something the right size. :-)
 
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Old 12-04-14, 08:57 AM
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Donít you just love all these different sizes? lol Itís a wonder all plumbers arenít crazy. (Maybe they are,lol)
 
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Old 12-04-14, 02:13 PM
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As for interchangeability, this is for the condensate drain on an HE furnace. The manufacturer states either is acceptable, it's just a matter of getting something the right size.
Yes, either material is acceptable but not BOTH at the same time. Stick with either the CPVC or the PVC for the entire drain.
 
 

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