Storing a compressor with air in it

[Arron]

Hi again,
I'm wondering whether there is any problem with storing a compressor with air in it. What I'm thinking is that I'll probably only be using the compressor for spraying once every few weeks, the rest of the time it will sit in a cupboard. However I'd like to be able to be able to take small items to it occassionally and be able to use it to blow dust off - using one of those air gun things - without having to drag it out of the cupboard, plug it in and fill it up.

So what I'm thinking is that when I've finished spraying, I could vent it to get the water out, then fill it up again with air and put it away. Is there any problem doing this ?

cheers
Arron

[Chris Parks]

Hi again,
I'm wondering whether there is any problem with storing a compressor with air in it. What I'm thinking is that I'll probably only be using the compressor for spraying once every few weeks, the rest of the time it will sit in a cupboard. However I'd like to be able to be able to take small items to it occassionally and be able to use it to blow dust off - using one of those air gun things - without having to drag it out of the cupboard, plug it in and fill it up.

So what I'm thinking is that when I've finished spraying, I could vent it to get the water out, then fill it up again with air and put it away. Is there any problem doing this ?

cheers
Arron

It may not hold air that long. As long as it is drained of moisture there will be no problems. You can buy compressed air tanks to do exactly what you want and use them as a portable air supply.

[soundman]

A great many compressors are never turned off, so their tanks and lines stay at full pressure 24/7/365.

My compressor is permanently powered up and has been so nearly continuously for over 10 years.

I have a cheap $100 compressor for fiddles, and it holds air for months,,,in fact it probaly has air in it now.

If you expect things to hold air long term ya have to be very fussy about leakage.

in short no problems.

cheers

[arose62]

I've heard of a spare tyre being used for this sort of application, or even to power infrequently used airbrushes.

Cheers,
Andrew

[nearnexus]

I have an expired 9kg LPG gas bottle that I use as a portable air source.

Very handy to blow dust out of PCs and do jobs on vehicles that are well away from the shed.

LPG bottles are rated at twice the pressure of the average air compressor.


So long as you make sure they are free of gas fumes there should be no problem.

One way is to fill them with water and drain and dry them in the sun.

Rob

[soundman]

Yeh air from spare tyres is a bit dirty and a bit inconvienient.

I too have a converted gas bottle that I use as " bucket of air".

If the gass bottle is a bit old, cleaning the putrification chemical out can be a bit of a mission.

yes fill with water, to expunge any remaining gass.

I sluced mine with petrol a couple of times and rinsed with water and detergent.
Then left sit full of water for a week.

blow out with compressed air and leave in the sun.

some bottles getting a fitting to mate after the gas valve has been removed can be a problem...som e bottles are straight BSP thread others are BSP gas which is more tapered and the metal is very hard to tap..even if you have a BSP tap on hand.

There are some air tanks available.....Tigers11 4wd accessories have a couple, an 9 & an 18 liter from memory the 9 i seem to remember has a handle.

Arlec used to sell a 20 liter in the chain stores but I have not seen one for a while.

cheers

[nearnexus]

I did away with the original brass screw in tap on mine.

I filled the cylinder with water and welded a steel tube into the top which is threaded for two small ball taps.

I then fitted air line connectors to each - one male, one female.

Makes filling from the existing supply quick and easy and all the airtools snap straight on.

Can supply a photo if anyone is interested.

Anything over a 9 kg LPG is a bit heavy to hump around.

Rob

[Bob38S]

I did away with the original brass screw in tap on mine.



Can supply a photo if anyone is interested.



Rob

Would appreciate a photo as I'm toying with adding a large ex gas bottle as extra storage fro my 10 cu ft McMillan tank.

[soundman]

If ya thinking about adding a second reciever( tank) to your compressor, look for a tank with a seperate input and output, prefereably at opposite ends of the tank.

If you do this you will drop the majority of water out of your air line.

I used to suffer from accumulated water in my lines and water pissing out of my air tools with heavy use.

I fitted a tank off an expired compressor and a filter reg after that and my air lines remain clean and dry.

this is what happens

the air comming out of the compressor its self is quite hot and carries moisture from the outside air and a little oil from the compressor.

the air in the first reciever remain hot and the moisture remains suspended in gassious form.

Filter regulators and moisture traps can only extract moisture in liquid droplet form, so this moisture goes straight thru the filter reg and moisture trap.

a second reciever allows the air to cool, slow down and drop its moisture as it passes thru the tank from one end to the other.

Now when it hits the filter reg, the air is considerably cooler and what remains of the moisture will be picked up by the moisture trap.

I run a second filter reg for spraying air......I have not seen any moisture in it since the second reciever was added and it has not been drained since.

This one of the single best improvements you can make to a compressed air system.

Your spraying results will improve and you air tools will love you for it.

cheers

[BobL]

Just a word of warning about adding too large a reservoir to a small (cheap) compressor. Most of the wear on a compressor happens during the last part of the pumping part of the cycle as this is when the compressor is at it's hottest and forcing it to continually run longer than this does add to wear. Adding a 9kg (18L) bottle should be OK but don't do like a mate of mine did and add a 100L tank to his new 2.5HP with a 40 L tank which died after about 8 months of use. Luckily he got it replaced under Warranty!

One of the most useful things I have done to my compressor is fit an automated venting valve. It consists of a 24V irrigation solenoid, a 24V power pack from and old irrigation time and a switch. I removed the existing vent valve and added a T-piece and put the old vent valve on one arm of the T and the solenoid on the other. The powerpack and the switch are inside the shed and wired back to the compressor which is located outside the shed.

[soundman]

Adding a rediculously large tank is indeed not clever, but most compressors will benifit from doubling the size of the sotored air capacity.

While the machine will run longer it will have less starts.

Besides....when I get to some serious use my compressor can run continuously for quite some time.
If I am drilling & riveting or using other air tools I frequently have to wait for it to catch up....and that will go on all day.
My machine has been doing thaty for over 10 years

The fact is that cheap compressors die young, and are not designed for continuous use...often the motor simply has insufficient ability to cool its self.

When ya cheap compressor dies thats where ya get ya tank from

cheers

[nearnexus]

Here's the LPG (bucket of air) tank I made up.

I centre bored some round stock and welded it in with the arc.

Simple setup which works well.

Fill it at the bottom fitting, close tap and good to go.

As the air has already been through the dryer there are no moisture issues to complicate matters.

Having fittings setup as shown I can use the tank before or after the regulator (eg to boost tank capacity - though this is rarely required as I have a 240 litre main.

These little portable tanks are very handy.

Rob

[soundman]

If ya get the right gas bottle there is no need to do any welding, lots of the cheaper bottles have a common BSP taper thread.
A trip to the local truck spares shop should get the right adaptors & taps.

Mine had a BSP GAS thread, it was hard work but a managed to get 3 clear threads of engagement and mounted a T piece with a female nitto on one side and a male nitto and a valve on the other side

It charges from empty to line pressure off my air hose in about 30 seconds.

If I need to top up a car tire, fire a couple of nails or blow some dust out of something, its much easier to pick it up rather than run out a hose or drag a compressor.

cheers

[nearnexus]

This whole gas bottle service life limit seems a bit over the top to me. I've seen more than a few LPG bottles cut open and there was absolutely no sign of rust or corrosion.

Compare that to an actual air compressor tank with water sloshing around in it that rarely gets drained - 60 years later it's still in service (home use).

Yet you never hear of any compressor tanks blowing up - they don't actually blow up, or rip themselves apart, they just leak air.

Rob

[soundman]

Ah yeh well, large industrial compressor tanks can blow up and with absolutely frightening results, that is why all compressor tanks in australia must be manufacturerd according to australian standards and in most states large industrial air tanks require inspection and certification.

The whole LPG gass bottle thing is more than the integrity of the actual cylinder.
More important that inspection for the cylinder integrity is, the inspecting the service valve for leakage and servicability and replacing the pressure relief valve.

A simple leak in an LPG cylinder is a whole lot more serious than a compressed air leak.

Put ya average compressor in a fire and some of the various plastic or rubber seals will melt letting out the air more or less harmlessly.

An LPG bottle in a fire is a whole other thing, this is why they have a pressure relief valve.

The issue is that it is cheaper to replace a small LPG bottle than to pay to have it serviced and certified.

If you look at large and more expensive gas bottles. They are more viable for recertification.

Every gass bottle should have a manufacture date stamped into it.....look at any steel industrial gas bottle and you may well find ( unless you are an old fart like me) it is older than you.
I have seen oxy and acetlyene bottles with dates going back to the late 60's and 70's. Steel argoshield bottles are likely to date back to the 80's

Anything of recent manufacture will be aluminium.

Likewise many large LPG bottles like are used for household or commercial supply could easily be 30 or 40 years old and have been recomplianced several times.

cheers