robocog
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| posted on 30/6/13 at 05:46 PM |
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compressor ratings
I have a small compressor that is a direct drive and it is noisy as hell
Up till now I have just put up with it, but I managed to bag a HVLP spray gun
Of course my puny compressor is unable to feed it correctly
(gun requires 14 and a bit CFM @ 20psi)
Am looking at belt driven compressors - and have found one that claims 145 psi and a flow of 9cfm
(airmaster tiger - chap claims its a 10/65 model but google is not assisting me, but insists on showing me other models with very similar model
numbers- maybe the chap wrote it down wrong)
Am I right in thinking that the CFM is quoted at max PSI?
I can live with waiting for the tak to replenish (not using it to do a whole car)
any boffins know if its possible to work out if it will be capable of running the spray gun for more than a couple of seconds at a time bursts 
I could possibly put up with joining my old compressor to the new one for the limited ammount of spray gunning I actually do..but it would be nice to
make it go out of earshot permanently :-)
Regards
Rob
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theprisioner
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| posted on 30/6/13 at 10:47 PM |
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My compressor is apparently able to deliver 21.8 cfm at a maximum pressure of 145lb/sqin or 10bar and a receiver size of 300L
http://toolstoday.co.uk/product/73711/sealey-compressor-270ltr-belt-drive-2-x-3hp-with-cast-cylinders?cat=2283
The two stats cfm and pressure should never be mixed up but, you can run a spray gun on a fraction of that capacity I have today. The key item for
spraying in my opinion is the receiver size. All you do is spray till the motor kicks (when the receiver is below pressure to spray) and retire till
it fills up again. I got adequate results from a 50L receiver. If that is not adequate then add more extra s/h receivers (tanks) till you get the
spray time you need. My compressor is outside, it would be deafening in the workshop. All you have to do is insulate the small building you locate it
in.
http://sylvabuild.blogspot.com/
http://austin7special.blogspot.co.uk/
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Peteff
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| posted on 1/7/13 at 08:06 AM |
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I have an old 3hp V twin direct drive Sip compressor and at 30psi it will refill the tank while I am still using the gun. What you need to know is the
FAD (free air delivery) which is usually roughly about 2/3 of the manufacturer quoted CFM figure. My receiver is only 50 litre but fits in with what I
need without taking too much space. Bigger tanks just mean waiting longer for the pump unless you have a massive pump and motor as well.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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robocog
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| posted on 1/7/13 at 07:22 PM |
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OK current compressor is capable of running the gun at 20 psi for 45 seconds before the motor kicks in
It is not capable of replensishing faster than I am using it and I forgot to time how long it takes to top back up to its max of 120 psi and motor
turn off...but its possibly about 30 odd seconds maybe slightly more (short enough to work with?)
I didn't think to see how much longer I can hold the guns trigger before the pressure starts to drop to below the required 20 psi...but I
wouldn't think it could sustain it for long and would not be good for the machine I'm sure
I think I /may/ have sourced another aircap for the gun that is less demanding (only consumes 9cfm at 20 psi) so it should extend gun on time's
a bit (considering the current air cap is gobbling a quoted 14 and a bit cfm at 20 psi!)
It's not true HVLP..but meh...still efficient according to the blurb
That double compressor linked looks a mightly beast.
I am looking at more manly (belt drive!) compressors than the direct drive one I currently have but I certainly don't have a 4 figure wad to
throw at it 
(also limited to single phaze and no more than a 13 amp plug)
I guess something that CAN lob out 15 cfm free air or even at 20 psi is going to be expensive and big and potentially over my current electicity
supply can handle
Maybe 45 seconds spray time is going to be long enough as long as I do things bit by bit?
Still reading up and searching :-)
I am curretly looking at a twin cylindered 50 litre direct drive unit...and its not too far away for me to collect
Quotes 240 l min for free air - so 8 and a bit cfm?...would still have to wait a little bit now and again but surely better than the single one I
currently have
Regards
Rob
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