Should I Use PVC Piping With Compressed Air?
Polyvinyl chloride pipe gets used in all sorts of various applications these days, and there are probably a few reasons for that. PVC costs less than most of the alternatives out there. It doesn’t corrode particularly easily, and it’s relatively strong. Plus, it’s readily available. PVC pipe works really well in a variety of applications, not the least of which revolves around transporting liquid. Because PVC stands as a really versatile and rugged option, it makes sense that it gets used for all sorts of applications, even ones that it might not be an ideal fit for. Compressed air or other gasses fall into this camp, though folks have used it plenty for this application. It is a viable option, at least initially. But, should you actually use PVC piping with compressed air? The answer, given the obvious direction we’re taking with this article, probably won’t surprise you.
The Problems With Using PVC Piping With Compressed Air
As previously mentioned, PVC piping has its definite benefits, but it also has some pretty obvious drawbacks as well. The first, and probably main thing worth noting revolves around PVC’s susceptibility to explosion. This becomes problematic, as exploding PVC will shatter, sending plastic shrapnel everywhere. Ultimately, using PVC piping with compressed air presents a health and safety risk, since PVC is a lot sharper and harder than all your fleshy bits.
Age And Temperature
Of course, PVC doesn’t just shatter or explode out of nowhere. Most consumer air compressors only compress to around 125-175 psi. This doesn’t seem like a whole lot, especially when even the smallest size PVC pipe can generally handle anywhere between 300-600 psi. However, these stats only really hold any value when the PVC pipeline is new and sealed properly…which brings up a couple more issues surrounding the use of PVC piping with compressed air.
For one thing, PVC becomes much more brittle as it ages and as the temperature drops. The manufacturer psi ratings really only apply when the PVC is “fresh”, for lack of a better word. Take 10-year-old PVC pipe, for instance. The initial rating, at that age, becomes pretty meaningless since the plastic has had 10 years to degrade. Plus, when PVC runs into freezing temperatures, its structural integrity becomes compromised, making it much more prone to shattering.
In either of these cases, impact will likely be the catalyst for PVC failure. For this reason, and due to the numerous injury cases reported over the years, OSHA does not allow the transportation of compressed gases in above-ground applications. They will, however, allow the use of buried PVC piping with compressed air, but this option opens up a whole new can of worms…
Another common problem with PVC in general, but especially as it applies to using PVC piping with compressed air, comes down to how the piping has been sealed. PVC pipe is notoriously difficult to install and seal properly, and leakage has become a common concern. PVC cement doesn’t often get the sort of time it needs to properly set, or the thread sealant fails due to improper application techniques. At any rate, a compromised compressed air system becomes a dangerous, and potentially ineffective, compressed air system.
Repairing these issues might be less of a problem when your compressed air system exists above ground, but again, OSHA does not smile kindly on that sort of operation. They will allow you to bury your PVC system underground, as the risk of pipe explosion won’t put anyone at risk. The problem here, however, is that you still run into the same proneness to failure as you would with above-ground systems: compromised structural integrity due to low temperatures, possibly shoddy sealant work, and the effects of aging. The need for repairs will undoubtedly spring up, but guess what? You’ll need to dig up all your pipework to repair it.
A Better System
Rather than using PVC piping with compressed air, you’re better off with any number of metal options. Copper pipes, steel water pipes, galvanized pipe, and aluminum pipe can all handle the task. You won’t run the risk of explosion, and the material won’t degrade like plastic will (black iron pipe ought to be avoided as it corrodes very easily). Plus, and this may be the biggest benefit to using metal piping, OSHA won’t show up to your jobsite, flipping out about your above-ground compressed air system.
Another alternative out there different from metal and PVC is PEX piping. PEX seems to be catching on for running compressed air lines. It can hold some pretty extreme pressures (750+ psi) and it splits when it does fail – not explode like PVC. Who knows what OSHA’s take on the PEX air alternative, but I’m sure we’ll find out soon.