What is the difference in conduit schedules?


Old 06-20-05, 03:29 PM
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What is the difference in conduit schedules?

For example I always see schedule-80 or schedule-40 printed on PVC conduit. What does it mean? What are the available schedules and what are their differences?
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Old 06-20-05, 06:05 PM
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The higher the number the the thicker and stronger the wall.
Lot's of Info on google.


Here is some I found.

In the United States, "Schedule" refers to the thickness of the pipe wall and, therefore, how much pressure it will hold. In most aquaculture applications, Schedule 40 is used because:

It works for most applications and is readily available.
In small quantities, it is only slightly more expensive than the thinner wall Schedule 120.
The wall is thick enough so that it will not distort when walked on.
From 1/2" to 2", it is rated at no less than 140 psi at 73F. The highest pressure typically found at any facility is 65 psi, which is the average city water supply.
Schedule 80 is rated at no less than 200 psi at 73F (up to 2") and is usually gray (similar to the Schedule 40 pipe used for electrical conduit).
There are very few reasons to ever need such a heavy, costly pipe for aquaculture. The outside diameter (O.D.) is the same on Schedule 120, 40 and 80, so an expensive Schedule 80 fitting could be used on Schedule 120 or 40 pipe, if that's all that was available. As the wall of the pipe gets thicker, the inside diameter (I.D.) gets smaller. With fittings, the outside diameter gets larger.

The main reason to use Schedule 80 is if it is mandatory in your area for specific applications.
Old 06-20-05, 10:31 PM
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joed got his metaphors mixed a little. SCHEDULE 120 would be extermely heavy and is rarely if ever seen. CLASS 120 pvc pipe is used in the landscape industry. It has a pressure rating of 120 PSI, and is very thin walled.

I am not sure if in the electric trade that anything other than schedule 40 is used. More important, electrical conduit must be UL listed, which schedule 40 water pipe is NOT. Also, plastic conduit could be used in a water system, but schedule 40 galv. electrical conduit must NEVER be used as gas pipe.
Old 06-20-05, 10:42 PM
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Sch 80 pvc conduit is sometimnes used. PVC conduit can not be used for potable water. PVC Water pipes are listed (I think NSF lists water pipes)
Old 06-21-05, 06:32 PM
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I cut and pasted it direct from the site. After I looked again I figured was probably supposed to be sch20 but that is how they had it at the site.
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