Thread: Small workshop compressor - any non-petrol options?

Im a little lost, as id never consider a petrol/diesel powered compressor, unless i lived in the country or worked on site with no access to electrical access.


most people just use air compressors, connected to a a 10 amp plug in there home workshops, unless they have 3 phase or a 15 amp socket

The smaller 10 amp aren't great for spraying, as the airflow isn't great, 15amp with a LPM flow is better, I've got a Pilot 15 amp compressor and i find it just suitable, having said that i have the 50ltr instead of the 100 ltr tank as i have space issues.

I have a small electric compressor (<$150) that is adequate for about 75% of my needs; mainly a brad nailer & topping up tyres. When I use it with rotary tools such as a die grinder it quickly runs out of puff, and as a sprayer it is very frustrating having to stop and wait for it to build the pressure back up.

However; if I was to buy a 2.2hp unit the problem then would be waiting for the compressor to fill such a large tank when all I might need it for would be to put in a dozen staples; but would be fine for the once or twice a year when I need to spray something.

If you definitely want to spray finishes then go for the biggest you can afford; preferably an oil-free model. But if your air usage is pretty low then a small 1hp unit may be all you need.

I have a 10amp compressor I got cheap from Super Cheap Auto. In other words nothing flash. I can't remember the exact size but it is fine for nailing, cutting and spraying. Im traveling now but I can give you the details when I get home if you like.
With spraying it has to work hard but I don't actually run out of pressure.
I sprayed both sides of all the cupboards from our large kitchen. Two at a time. That's about 8 hours spraying per coat. The compressor was often running almost half of the time I was spraying but I never actually had to wait for it. It has two values. From memory the machine it set for 120psi and the outlet for spraying is 40psi. Hence the machine can drop a lot and slowly build back up without ever affecting the spray.

I have also used it to build a new wall in the house at the end of a 30m hose. No problem even though the hose was leaking.

What you have to avoid is attempting to run the compressor at the end of an extension cord. Use a longer hose instead.

I usually wheel mine outside under an external outlet it have. I do this due to the noise and because I normally work out there in the carport anyway.

If you were worried there are better, more power, larger cylinder 10amp compressors than mine.


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Petrol compressors are really annoying to use and as bryn said is more of a necessity rather than an option in my book, the constant noise and maintenance is definitely worth avoiding if you can help it.
Whats your setup like at the moment? do you have 15 amp sockets or 3 phase? if you do then you should be able to get a sufficiently large compressor to meet your needs. Alternatively there are a few on the forum running 3 phase compressors on VFD's so there are routes that you can go down.

It also depends on how much spraying you're planning no doing, as this is where most of the air requirements will come from and might be worth looking at getting an airless sprayer. Then you don't need to worry about losing air pressure mid spray and water in your lines etc.

Thanks all!

I realise now I have been misreading spec sheets, so a lot of the units I was thinking were petrol are electric . I now have to start my homework all over again...

I do have 3 phase and 15 amp circuits available so it sounds like I have some options. Is a second hand unit likely to be OK? I worry about a second hand pressure tank with an unknown history, that sounds a lot like a second hand bomb!

cheers,

Danny

Originally Posted by tonzeyd

It also depends on how much spraying you're planning no doing, as this is where most of the air requirements will come from and might be worth looking at getting an airless sprayer. Then you don't need to worry about losing air pressure mid spray and water in your lines etc.

This is very true. I have both an airless sprayer and and air compressor. They do very different jobs.
The airless sprayer is designed to spray large quantities of paint. It is useless if you want paint the average woodwork project. Basically anything less than about a litre of paint is going to be difficult or even impossible. At least mine is.
It is much, much faster. I can paint an entire room in minutes. Excluding setup. And the results are excellent.

The air compressor isn't suitable for water based paint. At least mine isn't. But for oil based paint, polyurethane etc it gives an even better finish than the airless sprayer. You can do very small quantities if you want.

Both require a bit of technique but it is easy.

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Originally Posted by Chief Tiff

However; if I was to buy a 2.2hp unit the problem then would be waiting for the compressor to fill such a large tank when all I might need it for would be to put in a dozen staples; but would be fine for the once or twice a year when I need to spray something. .

This won't suit many people but unless I go away for more than a day, I leave my 4HP/19CFM/70L compressor on 24/7 so there's no waiting
The compressed air is reticulated throughout the shed via ~20m of galv water pipe to 6 take off points on 3 walls and up near the ceiling in the middle of the shed
3 of these takeoffs have short (2m) hoses connected for compressed air tools, one is connected to my plasma cutter and one has a 20m long compressed air hose on a reel near the shed door that reaches most of my back yard.
There are about 2 dozen junctions (elbows and T's and 6 valves) so there are many possible leak points but it only recharges itself about once per day so its not too bad and the cost of electrical power to do that is ~$1 per month .
A mate has a similar system(100L tank) but uses a valve that shuts off the reticulation arm at the compressor and only opens the valve when he needs it. His compressor will hold pressure for weeks if he doesn't use it.

My compressor itself is located in a semi sound proof enclosure outside the shed.

Originally Posted by rtyuiop

Thanks all!

I realise now I have been misreading spec sheets, so a lot of the units I was thinking were petrol are electric . I now have to start my homework all over again...

I do have 3 phase and 15 amp circuits available so it sounds like I have some options. Is a second hand unit likely to be OK? I worry about a second hand pressure tank with an unknown history, that sounds a lot like a second hand bomb!

cheers,

Danny

all good, at least your on the right track now.

There are a lot of cheap three phase out there on eBay and gumtree, although you will find the three phase are quite big as they are designed and sized for commercial use, id only personally buy one if i was spraying every day and had a three phase outlet there.

Secondhand units are hit and miss, a question to ask is if the owner drains the tank weekly, to remove condensation in the tank.

The compression in the head maybe something to look at, others will have a better idea on testing that.

As for secondhand, like anything, its hit and miss, knowing what to look for and then hope for the best.

Originally Posted by bryn23

all good, at least your on the right track now.

There are a lot of cheap three phase out there on eBay and gumtree, although you will find the three phase are quite big as they are designed and sized for commercial use, id only personally buy one if i was spraying every day and had a three phase outlet there

There is another reason to buy one, and that's if you're in a residential area. Compressors are noisy, so I figured a largish 3ph unit would limit the amount of time the pump would run to maybe once a day in my typical use. Using my neighbour's small 2hp unit with a 24L tank, I can fire my framing gun 6 times and then wait for the compressor to catch up. The Abac with a 150L tank, about 50. Takes about the same time to repressurise, and is a bit quieter too thanks to the slower rpm pump. It's worth it to keep on the good side with my neighbours and keeps the noise down a bit for me as well.

I do intend to fit an auto float drain, these remove the condensate with minimal or no air loss and are pretty much maintenance free.

I had a look at one of those auto float drains but unfortunately I could not used it for my specific compressor situation
- The tank drain is in between the tank legs at one end of the tank so there's not enough room to attach an auto float drain directly to the tank.
- To get around this I could add a extender pipe to the drain hole but then I would have to lift the whole tank up so the an auto float drain could fit underneath.
- Then I run into trouble with my compressor enclosure not being tall enough to accomodate lifting the tank up

In the end I use one of these units to drain the condensate.
Automatic Electronic Timed Air Tank Water Moisture Drain Valve For Compressor | eBay
I have it venting for 1/2 second every 45 minutes and I also constrict the outlet so it uses very little air. It's on a timer so it only operates during the day and like the compressor I switch it off if I go away.

Thanks all. I think I might keep an eye on ebay and gumtree, see what the market looks like. I'm not sure how often I'll use it, so hoping to keep the expense down!

I have a silenced electric compressor, its a 10hp, 43CFM. It seems you have 3 phase so just get the biggest you can. compressed air is something you will never have enough of.

You might want to consider a refrigerated dryer if you are doing spray painting.

here is a video clip of me turning it on

Originally Posted by Albert

10hp, 43CFM.

Doesn't quite seem consistent with rtyuiop's wish of "hoping to keep the expense down"

I'm pretty sure he's not going to be able to pick one of those up for $200-300 bucks