Thread: Air Compressor and fixed air lines recommendations for shed fitout

This hardly a completely definitive test but it's still interesting.

The other plastic hose that can be used is braided vinyl which I use this as the working flexible extension between a fixed point of the comp air line and the tool
The one I use is 1/2" and has a max working pressure of 230psi and burst pressure of 930PSI.

Over time it goes hard and lose flexibility - eventually they leak but even when they have gone relatively hard they don't explode maybe the braid prevents that. Usually they leak at junctions. They don't like accidentally being left up against a grinding wheel for too long - no explosion just a loud hiss.the embarrassing thing is that this I have done this twice

Originally Posted by jack620

derates to about 150psi for air.

And in that lies the rub.

Single stage compressors can achieve 150 psi if there is a failure in the control system and the pressure relief fails to work. It does happen.
Over the last 10 years there has been a shift in Australia to two stage 175 psi compressors in the DIY market. There have been cases of guys taking their new high pressure comps home plugging in to their old systems with something letting go.

I find it interesting that on the net there are lots of talk about the dangers of tanks going bang but not a lot about the dangers of an under spec or aging system letting go and the subsequent injuries it can cause.

Tony

Originally Posted by BobL

This hardly a completely definitive test but it's still interesting.

Cheap easy to assemble.

Originally Posted by bts

And in that lies the rub.

Single stage compressors can achieve 150 psi if there is a failure in the control system and the pressure relief fails to work. It does happen.
Over the last 10 years there has been a shift in Australia to two stage 175 psi compressors in the DIY market. There have been cases of guys taking their new high pressure comps home plugging in to their old systems with something letting go.

I find it interesting that on the net there are lots of talk about the dangers of tanks going bang but not a lot about the dangers of an under spec or aging system letting go and the subsequent injuries it can cause.

Tony

So if the electrical controls fail. Then the safety don't lift. Bursting disk doesn't burst. It's still unlikely to cause any injury in the shed.

Doesn't seem that dangerous to me. The tanks even it's not like you sit on them for smoko. Even if it is damaged by rust it will more than likely develop a slow leak.

Originally Posted by jack620

Agreed. But derating a pipe isn't exactly onerous either. Take the rated water pressure and divide by the derate factor for the expected working temp. At 40C a 200psi water rating derates to about 150psi for air.

Originally Posted by jack620

Not so Bob. From the following document: https://www.pipa.com.au/wp-content/u...8/09/tn011.pdf

"An important difference that needs to be understood relates to the relative pressure derating of pipe for compressed air applications. The reason for this derating is that compressed air is a gas that is under pressure and as such contains substantial stored energy - more so than a liquid under the same pressure. If that energy is released suddenly there is an increased risk of injury to anyone nearby. For that reason there is a greater factor of safety applied to pipe for compressed air applications than would be applied to a pipe carrying water at the same pressure and temperature. Therefore the allowable working pressure of a compressed air pipeline is less than the PN rating of the pipe."

Hi mate .so does this mean " that the compressed gas is only more dangerous if the pipe has a rapid decompression?
If it doesn't blow up it's not dangerous? How would a pipe know if it's full of gass or liquid?

Gas expands as it decompress. Turns things into projectiles.
Fluid does not compress so no expansion.

Look up air tank explosion on google

Tony

Originally Posted by bts

Gas expands as it decompress. Turns things into projectiles.
Fluid does not compress so no expansion.

Look up air tank explosion on google

Tony

Yah but Na. . Not likely to happen thou ? Is it. ?

Originally Posted by azzrock

If it doesn't blow up it's not dangerous?

Congrats, you win the Dumbest Question Of The Day award.

Originally Posted by bts

Gas expands as it decompress. Turns things into projectiles.
Fluid does not compress so no expansion.

Perhaps "may turn things into projectiles" is a better descriptor?
Right now there must be many thousands of litres of air being decompressed around Australia and nothing is being projected - except the air and maybe a bit of paint.
Projectiles only eventuate if the container or pipe shatters, or burst object is not constrained.

By far the majority of compressed air line and compressor tank failures are leaks, or less often rips/tears without any sort of "explosion". Thats not to say explosions don't happen but they are relatively are rare. Perhaps not as rare as wood dust extractor spark induced explosions. Given the very large numbers of old rusty compressor receivers out there, many full of water, I'm surprised it doesn't happen more often. How often do you vent the condensed water out of your tank?

"Not constrained" results in the recoil of pipe or tank from any rapid decompression - ever been hit it the teeth by a compressed air push fitting being released without sufficient constraint? This problem is exacerbated if the object being propelled keeps being propelled but most pipes would affixed well enough to prevent this. For compressors it depends on the size of the explosion - I have heard of one been thrown across a workshop - luckily no one was there at the time.

Technically air is a fluid, I think you may mean liquid? Liquids don't expand (much) but continuous rapid loss of liquid under pressure can have consequences eg loose fire hose.

Perhaps another reason to locate compressors outside sheds.

For a change maybe we should discuss air embolisms?

Talking of compressors, leaks and hoses I noticed today that the compressor was cycling a bit more than necessary. Its not a completely sealed system as the auto vent mechanism regularly released small amounts (50ms every 50 minutes) of air so, even when I'm not using air, so it usually only recharges about once a day - but today it was about every 4 hours.

So out with the dilute dishwasher detergent and paint brush and found it was one of the joins outside the shed where a flexible braided hose from the compressor joins the solid copper cooling coils. Its a barbed 1/2" BSP connection and the hose is held onto the barb wth a standard hose clamp. About a 1/2 turn on the clamp screw stopped the bubbles.

Hard to say but leaks seem to happen more often when there is is a major change in the weather and it's nearly always a join outside the shed that leaks.

Is it time to give the thread back to the OP?

Originally Posted by azzrock

Yah but Na. . Not likely to happen thou ? Is it. ?

Yea I no I am being pedantic on this but I have seen the end result on two major failures. One a tank tried to go through a double brick wall. Luckily it did not make it as 5 people were working on the other side of the wall. The other was an old PVC system blew when an electrician bumped it with his ladder. Luckily they got away with a couple of shards of PVC in their forearms.
When I was working in the pneumatic field two gentlemen I worked with had nearly 80 years in the game between them.
Between them they had some horror stories especially the one that had spent years working for the government checking accidents and safety inspections.

Just because it has not happened to you does not mean it does not happen.

Tony

Kept it simple here at the shop and simply ran the flexible air comp line on the wall top hats around the shop. Tee off where I need a drop.

Added to it over time. Some sections would easily be over 5 years old. Where it goes over metal edges (say over the top of the columns) ran some poly pipe over it.

Temps around here span from into the 40s right down to just below zero over the course of a year. Some sections of hose are touching the cladding on the Nth side, so no prizes for guessing how hot it would get.

Run a water trap at the comp and one at the cutter. Very little water found at either end of the line.

Comp sits outside under cover. Admit to being a bit anal with dumping any excess water out of the comp tank.

I run a Peerless PHP15, 2 stage, single phase unit. Good unit in my humble opinion.

Originally Posted by BobL

At the mens shed we used blue line black poly pipe...

Did you join any copper lengths into the poly for water condensing? Are there fittings to achieve this? What was used to connect the outlets and drain taps to the poly?

I am taking another look at 32mm PE100.