Compressed Air Piping

Demonic said
Do not use PVC.

You can say that again!

Demonic said
The pipe is not the problem, it's the fittings. They get brittle and oxidize just from age, and explode after a few years.

Maybe true. But once it goes, its all over. Not sure if he (the landlord) had it installed more than a year or two. No more than that.
Larger diameters probably increase the stresses in the material.