How big an air compressor needs to be?

Post by **RogerRust** » Fri May 30, 2008 8:04 am

I'm thinking of installing a compressor in my garage.

How big a unit do I need?

I want to run air tools and a polisher.

Also has anyone done a class job on silencing a compressor - building an enclosure etc?

Post by **Welung666** » Fri May 30, 2008 8:23 am

I built an enclosure for my local tyre place. Simply a 2"x2" frame with 1" marine ply screwed on, completely lined it with rockwool held in by stapling plastic sheet around the edges. Standing the compressor on rubber blocks helps noise too.

PS Don't forget to build in a door so servicing/draining etc. can be done.

Post by **RogerRust** » Fri May 30, 2008 8:30 am

Lee, Did it work?

Post by **superchargedfool** » Fri May 30, 2008 8:39 am

dont forget ay enclosure must be well vented to allow cooling, obviously not vented to where you are working though cos of noise.

best form of silencing is to put compressor in a different building than where you use the air.

150litre 3hp is the minimum size for propper use.

Post by **AndrewSkinner** » Fri May 30, 2008 1:04 pm

High Roger. Welung has got it spot on. Build a simple frame from wood or metal the sheet over with wood panels or something like tounge & groove. Superchargedfool also has a hugely important point!!

Compressors get very warm, not only from the motor running but the huge energy required to sqash air. pipes leading into the tank and the compressor body get too hot to touch. you will need an air vent at either end as the motor normaly draws air in and past all the components.

You need to drain the tank after everyuse and leave it open if possible to allow any moisture to evaporate. manufactures also say you are not supposed to leave the tank compressed for longer than an hour at a time. I think this is just covering there backs but obviously when its not in use, let the pressure out.
I have a 3hp, 250ltr tank and it has run everything so far with ease, Impact drivers, air drills, sanders, air chisels and grit blasting

Post by **Alec** » Fri May 30, 2008 8:47 pm

Hello Roger,

compressor size is determined by what tools you wnat to run and the time you want to use them for. You need to know the consumption figure for the tool(s) and the free air delivery for the compressor. In practice, with even the largest single phase unit you will not be able to use any tool continuosly. (Well the ones I have anyway?)

"manufactures also say you are not supposed to leave the tank compressed for longer than an hour at a time."

That sounds very dubious, certainly I have had mine on for more than a day when I've forgotten to switch it off. Commercial or industrial tanks are pressurised continually in most cases.

Alec

Post by **paulk** » Sat May 31, 2008 10:47 am

"manufactures also say you are not supposed to leave the tank compressed for longer than an hour at a time."

Ours has been compressed 24/7 except bleed downs since 2002. No probs.

The larger the motor and the bigger the tank you can fit in the better.

I find if spraying then some of the older HVLP guns can use phenomenal amounts of air, Admittedly I'm also running 2 air fed face masks cos its 2 pack but the compresser can almost run continuosly if spraying.

It depends on what you are wanting to do But i would still get The biggest you can because your bound to want the next Air powered goody and then the next and so on

A 3hp 50 litre unit is probably the biggest you will want in your garage. Although the bigger 100 litre could come in handy if you can
A) afford it
B) find somewhere to put it

Our work 200litre unit gets drained out once a week and that doesn't tend to have huge amounts of water in but its far too big for a home set up and unless you get a double compresser unit its only sensible in 3 phase.

I f you can put it in a small Box/shed outside your garage it will certainly make working in the garage more comfortable.

Post by **WPR678B** » Sat May 31, 2008 10:56 am

paulk wrote:its far too big for a home set up and unless you get a double compresser unit its only sensible in 3 phase.

I have a single phase 200 litre unit and it works fine. It is a little big, but the garage its in is also a little bigger than standard!

Post by **paulk** » Sat May 31, 2008 11:01 am

I've seen you place mate and standard 'Home setup' is not a phrase I would use to describe it

:)

Post by **polo2k** » Sat May 31, 2008 11:04 am

Ive got a big ol' 100L 2.5Hp (might be a 150L)
I was contemplating selling it for either;
A) a vertical tank version of a similar size
-or-
B) buy a seperate pump and tank, mount both in the rafters of the garage (soundproofed to the underside) with an extended drain and an air take off in the usual position.

another thought I had the other day was, grass needs airated soil and a compressor dumps a lot of fairly dry air every time I use it. Since the garage is at the bottom of the garden could i plumb in a pipe under the grass so that when I dump the compressor it pumps air into the soil and aerates the soil??? or would it end up a big magic carpet?

Post by **paulk** » Sat May 31, 2008 11:06 am

Could be interesting watching worms clearing your house eaves

Also there are easier ways of getting rid of moles

Post by **polo2k** » Sat May 31, 2008 11:10 am

HAHAHAHA!!!
Maybe you could tell a local oil prospector that gou have a gas field in the back garden lol.
I shouldimagine there would be more flying ants too lol

Post by **Welung666** » Sat May 31, 2008 12:17 pm

RogerRust wrote:Lee, Did it work?

Very well indeed. The workshp was 30' wide and 75' long with the comp in the rear right corner. You could barely hear it running from the middle of the workshop.

As for the heat/breathing he'd had half a dozen air bricks added to the outside wall to help with that.

Post by **rob.hardy1** » Sat May 31, 2008 12:49 pm

I have been look at compressors and i suppose it would be
Suffice to say if i got this i could put it next to the chocolate tea pot

http://www.sipuk.co.uk/acatalog/sip_air ... #aSIP01585

( the top one)

Post by **jonathon** » Sat May 31, 2008 12:51 pm

Roger you really need to go by the CFM rating. To run D/A's spray guns,ratchets etc you will need up to 6cfm. If you are interested we have a Boge screw compressor which is almost silent in running its 150cfm feeding a 300ltr tank and freeze dryer. The dryer and tank have auto bleed valves which cost around a tenner each.This machine will feed 3 people using a variety of tools all day long ,no problem.
You should also consider a water trap with pressure regulator.
Do not use an oiler in the system or use airlines for painting that have had oiled tools on them.
Not sure about your budget but Boge have been brill

Post by **paulk** » Sat May 31, 2008 7:15 pm

Rob My brother in law has an identical unit to the one you showed and it struggles to pump up a slightly flat tyre (going from 18-30 psi took two tanks for a standard tyre)

Yes definatly put it on the shelf next to the chocolate teapot.

Except if all you want to do is use an air brush.

Post by **MGFmad** » Sat May 31, 2008 11:30 pm

paulk wrote:Rob My brother in law has an identical unit to the one you showed and it struggles to pump up a slightly flat tyre (going from 18-30 psi took two tanks for a standard tyre)

Yes definatly put it on the shelf next to the chocolate teapot.

Except if all you want to do is use an air brush.

I have a similar version to that but its made by Clarke - the same 6 litre capacity. I would agree that it would take time to blow up a tyre. However the reason I bought it was it was supplied with a nail gun and being only 6 litres, you can transport it into the house. Its brilliant as a nail gun but would imagine hopeless for spraying.

It will quite happily blow up the rubber band tyres on my MGF but took ages to put enough air into a Discovery tyre. But my big compressor will do this with ease.