Ahh! You bring good points. I had no idea what rating for pressure on PVC and CPVC was. So if the compressor is pushing that limit, then yeah, no go! It is one thing to have it spring a leak as the material breaks down over time, but under that pressure, it could become shrapnel, so I totally feel you about safety.

 

I will note that it varies by diameter and schedule. Given how cheap plastic is, I'd prefer to go larger ID to keep the flow rate up, but 1/2" is about the cap before the psi rating gets too low.

You can go higher schedule (thicker wall), but the local big box stores only carry schedule 40 (and I suspect shipping 10 foot pipes of a higher schedule would quickly make it as expensive as copper due to truck freight).


I do like to have the ability to run above 100 psi as I've had to do it a few times. One good example was my c6 balancer bolt. Ive got a 1/2" impact that should be way more than strong enough to break it loose. But it just sits there an bangs indefinitely with no movement.

I stick a pressure gauge right on the gun inlet and find I've got abysmally low pressure. I always kept the regulator on the compressor at 100, but was only getting about 35-40 at the gun while running it (due to lack of airflow). I had my usual go to 3/8" 50' hose, plus a little 6 foot piece of coiled 1/4" hose for extra maneuverability as its a tight squeeze in the engine bay.

Swapped over to a 25' 3/8 hose only and cranked the regulator up to 130 and the balancer bolt popped right off. I was finally getting 80 at the gun too while running. So I'd like whatever system I get to be able to handle full open on the regulator just in case.

 

Sorry to kinda hijack here but.. Is it safe to assume that after a certain length of air hose, you will start to lose pressure or not have consistent pressure? Say you run a bunch of soft line (air hose) in place of hardline (copper or alu) to set up a shop, thats not possible?

I guess you could run it all with a small inner diameter but then you have flow issues?

Running soft line with a larger inner diameter will give the flow needed but will lose pressure or be inconsistent with the regulator?

Ive been following this since I may be taking on this project myself soon.

 

Please do, that was exactly my hope with this thread. Its been a bit slow lately, so I figured it would be nice to get some discussion going.

There are formulas for restrction calculations based on air flow need. Essentially, every single item between the tank and the tool contributes a small piece to restriction (including every fitting, valve, filter, quick disconnect, and every inch of line). When you get enough of these tiny restrictions piled on top of each other, you can end up with meaningful pressure drop under load.


Some tools are more sensitive to pressure drop than others. For something like a sander or cutting tool, a drop in pressure isn't usually noticeable as its still doing work. If you get into something like an impact or paint sprayer, going under pressure has a notable impact on function.


One thing thats important to keep in mind is pressure during operation. When not running, the system will equalize almost instantly to tank pressure regardless what size the line (like running that tiny 1/8" hose for a mechanical boost gauge). But the thing that matters is keeping up with enough flow to maintain pressure while the tool is running.

It is ok, and likely isn't drastically more or less restrictive than a hard pipe of the same ID. You are somewhat limited on ID options for longer runs though. But for a regular garage, that's likely by far the most common way to do it.

You want to keep the diameter as large as is practical. Obviously a home shop isn't going to pay to run 1.5" hard pipe all over. I think this was my main issue on the balancer bolt- that last 6 feet of 1/4" line (plus having to flow through one more quick disconnect pair). That small hose just can't support the air flow from a heavy use tool.

Lots of variables though- tool air use, length run, total number of restrictions in the line, what kind of tool (ie does losing 5, 10, 20 psi matter). Theres equations out there to help calculate, but most people just wing it.

Its important to think of it as each restriction in the line taking away X psi at a certain flow. So right off your tank is your regulator -say set for 100psi. Now you screw in a hard 90 degree fitting and its down to 99.8 at the outlet (at a given flow). Then you add a filter which drops it to 98. Then a quick disconnect coupler set that drops it to 92. Then 50 feet of 3/8 line gets it down to 85. Another quick disconnect pair to hook up your tool and you're at 79 at the tool while running at the flow rate used for the calculations.

Thats just making up #s for the sake of discussion, but it gives you an idea of how a 100 psi regulator setting doesn't equate to 100 at the tool while running, and it also shows how every single piece in between has a negative impact on outlet pressure due to restricting flow to some degree.

Subbing a smaller hose for a larger hose in the equation will cause less restriction and thus yield higher pressure at the outlet.

If you've got concerns, the easiest way to check is add a pressure gauge on the inlet of the tool you're concerned about (preferably hard threaded between the tool and the existing quick disconnect - not by adding another pair of quick disconnects as theyre notorious for hampering flow). Then you can operate the tool and read the pressure in real time. It also lets you make changes upstream to improve the number (ie sub your 50 ft soft hose for a 25 ft, etc).


Also, to be clear, I was cheating a bit in my balancer example by jacking the reg pressure. You've got to be careful doing that as you can exceed the tool's pressure capability at rest which can cause damage, especially when your getting well above. The right way to fix things is to increase airflow of the components in between so you don't have as much pressure drop during operation in the first place.

 

I would say for me it depends on the tool size, for now, the size difference for 1/4 ratchet, 3/8 ratchet, die grinder, etc are all still much better to have air powered. Also time period use items, like sawzalls and angle grinders, where the battery will discharge in 45 minutes of continuous work. For the impacts and drills, battery for sure. I also like not having to worry about the hose scratching up a fender if it slips past a fender cover somehow.