Compressed air

[Phil Pascoe]

I need to get compressed air from one side of the bungalow to the other. My sensible head says do it properly in hard pipe and have done, but it would be much easier to run a hose through the loft and down into the 'shop. Is there any difference in pressure loss over a distance between the two? I would like to be able to switch it off remotely as well - could I use a switch with a relay to save a fairly large cable/flex running all (50') the way over? Other suggestions?

 

[Rorschach]

If there are no leaks then there won't be any pressure loss. With hard pipe though you can get more CFM. Depends on your application really.

What do you mean when you say switch it off remotely? The air or the compressor?

 

[Fitzroy]

Pressure loss is a function of velocity and internal roughness. In your situation I’d expect the hose to have a considerably smaller internal diameter than hard pipe, so a higher velocity at the same flow rate and hence a greater pressure drop. However, whilst the pressure drop will be bigger it may be small in both cases. If you have a hose length, operating pressure, hose internal diameter and flow rate I can do a calc for you on the expected pressure drop.

F.

 

[Phil Pascoe]

I'm not interested in the actual calculations, just which would be best. (Thanks for the offer, though.)
The tools I'd use are fairly low demand.
I'd arrange it so I could let the pressure from the workshop, but I'd like to be able to switch the compressor from there as well - I can't easily get to the other side sometimes, and I can't move the compressor for space and noise reasons.

 

[Phil Pascoe]

So, any suggestions? Is there a significant benefit to piping the air over rather than using a hose? I am inclined to do it, but it's more money and more work. Upsides? Downsides? It's uncharted territory.

 

[Sideways]

In plastic you'll never have to worry about rust - inside or out - and the extruded surface will be a little smoother than the equivalent galvanised pipe for what that's worth. If you can get hold of good quality plastic with the same internal bore as the metal pipe you'd use, I would fit plastic. I think you can get it with a safe working pressure up to about 10 or 11 bar so I imagine that is good enough.
I assume the pipe doesn't run anywhere hot that would reduce the safe working pressure of the plastic.
N.B. I haven't done this. I just had an "ahhh !" moment when I came across some plastic pipe for fixed air on some manufacturers website a few weeks back.

 

[novocaine]

Chuck a hose through. No joins to worry about.
Use 14mm if you can.
Polyurethane will be fine.

Hard pipe is great but for low pressure stuff its overkill.

 

[Phil Pascoe]

Toolstation keep the plastic pipe. £37.50 per five, 15metres in all. Knowing my luck I'd need 16 metres. 10bar at normal temperatures. Hose would be simpler - I'm only likely to run a small drill, small sander, die grinder maybe and airbrush.

 

[Phil Pascoe]

14mm i/d or o/d?

 

[novocaine]

Sorry was working in pipe rather than hose.
Poly 14mm is 10mm id which would be fine. Rubber 14mm would be 6.3mm and to small.

Id 14mm is a bugger to get

Measure the run before you buy anything.

 

[Distinterior]

Toolstation keep the plastic pipe. £37.50 per five, 15metres in all. Knowing my luck I'd need 16 metres. 10bar at normal temperatures. Hose would be simpler - I'm only likely to run a small drill, small sander, die grinder maybe and airbrush.

I didnt think you were allowed to use plastic pipe with compressed air unless it was a specific flexible hose...? I'm sure I read it somewhere?

 

[Phil Pascoe]

As it is described as "compressed air nylon pipe" I would assume they know what they're selling. I don't know.
Is it easy to fit reliable tails to the hose if I buy the hose without their already being fitted? It's far easier to use hose.

 

[Distinterior]

Sorry Phil! I was looking at the standard push fit pipe and fittings.

 

[Phil Pascoe]

Not only me who has no idea, then. :lol:

 

[flying haggis]

john guest do a range of fittings specifically for compressed air

https://www.google.co.uk/url?sa=t&rct=j ... t1oQkjQLY4

presumably you could use 15mm copper pipe with the correct air fittings ie elbows tees etc

if you type compressed air into the search box on the toostation site it lists pipe and fittings

 

[Phil Pascoe]

Thanks, I hadn't seen that particular site although I was looking at J.G. stuff.

 

[Phil Pascoe]

Could I use 15mm o/d hose with push fit fittings?

 

[flying haggis]

doubt it would seal properly

 

[Phil Pascoe]

I'm thinking of using this stuff -
https://www.ebay.co.uk/itm/QUALITY-ASSU ... 1613816172
The 15mm o/d could be an advantage as I've got loads of 15mm pipe clips.

 

[mbartlett99]

That'll work fine and 15m is nothing at all. You don't sound like an industrial user who needs to comply with various regs etc. just be careful of kinks and sharp edges obviously. I've used this stuff loads of times for jury rigged extensions when needle gunning etc and it'll be ok for domestic use. Parker do nice pushfits and I don't think much of regular hose tail/jubilee clips - always seem to end up leaking somewhere somehow.

If you want to gild the lily go for drawn stainless all the way through with stainless fittings throughout - it'll cost several times what your compressor did.