pvc vs cpvc glue

[Qapla]

...It's not glue and glue should never be used on water lines under pressure...

I was using the word "glue" interchangeably with "cement". Around here, when we go to the supply house, we tend to say "Give me a gallon of blue glue, or gray glue, or clear glue, or even 'purple glue' (yes they make a purple colored one not to be confused with the 'blue' that is 'waterproof')"

The primer is a softener that prepares the PVC for the cement...Cleaner is not the same as primer. Cleaner is for dirty lines. After you use the cleaner, then you have to use the primer and then clear cement on PVC.

Most of the "cleaner" I have used is called "cleaner or primer" by the people using it - they do not distinguish between them. You are right though, both products are made. They also make "clear" primer for applications where the purple color would be a problem to the finished product.

..That's a new one to me; however, I'll continue to prime it...

When you buy the fittings one at a time in a big-box-store or even the "contractor pack" they sell with 10 fitting in it, you won't see the notice. When you buy the box of 50 from a commercial supplier, you will sometime get the notice about the primer in the 1/2" and 3/4" fittings. I kept the first couple I found just in case someone complained.

PVC and CPVC are solvent bonded using MEK and Tetrahydrofuran in a thickened mix using PVC or CPVC resin resp to thicken the mix ... Altho CPVC is good to a higher temperature the bond area is so large that even a slightly softened hot bondline of PVC/CPVC++ mix would not allow the socket joint to spread.

That may be the case, but in the "real world" I have found CPVC to not bond properly when the incorrect cement is used and the connections are subject to blowout/blow apart. I have also found that CPVC is more likely to fail if primer is not used.