Alexphd1 Posted October 12, 2018 Share Posted October 12, 2018 (edited) I am looking for a 30cfm air compressor to power a pump also need a 3 phase generator at same time. My options are:- 1. Rent one (hate paying somebody for a loan of tools) 2.Buy a petrol one (very expensive) 3. Buy a 3 phase one and rent a bigger 3 phase generator when using it 4. Can I run two smaller 15cfm single phase ones grouped together? I like this idea as would keep one when finished job. 5. Buy a three phase and rewire to single phase. Any other options? Edited October 12, 2018 by Alexphd1 Link to comment Share on other sites More sharing options...
dpmiller Posted October 12, 2018 Share Posted October 12, 2018 I'd caution that to get a *true* 15cfm you'd likely be looking at a 4hp singlephase machine. I normally see 3hp machines as about 13 on a good day... What kind of pump is it you need to run off air, and for how long at a go? Link to comment Share on other sites More sharing options...
Alexphd1 Posted October 12, 2018 Author Share Posted October 12, 2018 (edited) Its for spray machine, manufacturer states 30cfm but we are running machine at about 2/3 of capacity. Edited October 12, 2018 by Alexphd1 Link to comment Share on other sites More sharing options...
Russell griffiths Posted October 13, 2018 Share Posted October 13, 2018 Thinking outside the box, have you looked at a towable diesel compressor, like the ones used for a jack hammer, these can be picked up relatively cheaply, 1 Link to comment Share on other sites More sharing options...
Alexphd1 Posted October 18, 2018 Author Share Posted October 18, 2018 Is it possible to group together compressors to hit a higher output? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 18, 2018 Share Posted October 18, 2018 13 minutes ago, Alexphd1 said: Is it possible to group together compressors to hit a higher output? Yes, but be aware of the impact on the electrical supply if doing this with electrically driven compressors. Most compressors have a pretty high starting current, which is OK when you're only looking at one starting and drawing a high current for a short time, but may be an issue with a couple of compressors trying to start at the same time, which will probably happen with compressors in parallel, as they will all tend to want to start and stop at the same pressure. A 13 A outlet is OK for 3hp, but not really for 4hp, as 4hp = 3.056 kW = 13.28 A at 230 VAC, with a starting current that may well be over 20 A. 1 Link to comment Share on other sites More sharing options...
Russell griffiths Posted October 18, 2018 Share Posted October 18, 2018 Can you not get a broken large compressor and use the tank as a storage vessel im not up on the system but I know on an American garage forum I used to use it was common to have a larger storage unit with a smaller compressor topping it up. 1 Link to comment Share on other sites More sharing options...
dpmiller Posted October 18, 2018 Share Posted October 18, 2018 yup, you can have any size tank you want, you'll just wait for a small pump to top it up. Link to comment Share on other sites More sharing options...
scottishjohn Posted December 5, 2018 Share Posted December 5, 2018 yes i know about these things from car spraying etc--you can get away with a smaller compressor with a LARGE reciever every now and then you might need to give it a minute or 2 to catch up . basic rule of thumb 1hp =4cfm for continous use. If you want to rent a generator yo will find 3phase garage compressors very cheap s/h, even screw types now my guess older hydro vane or something like that 40cfm --£300 Link to comment Share on other sites More sharing options...
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