3HP Compressor quality and noise

I am looking for a bigger compressor and I know that I would like a 3HP, belt drive 14cfm with a 100 litre tank. This is the biggest I could run on single phase 13-15 amp and I only want occasional spraying and air tool use.

There are a number of known suppliers (e.g. R-Tec, Thorite, NuAIr) who stock branded compressors to this specification in the £480 - £560 (incl.vat) price band. However there is an equivalent compressor called a Burisch BT390 that is available for £276.

Now that is a lot less money for my intermittent use, but why is it so much cheaper? Is it going to be horribly noisy or will it fail after 12 months? If I ask the suppliers I know what they will tell me, but I would be interested to hear any independent view.

I have the Burisch BT3100V which is the v twin direct drive 100L. It runs fine off a 13 amp supply, not too loud but I would not want to be standing right next to it for a long period. It runs all my air tools and build quality seems fine. The belt drive model should be quieter but other than the silent types they all seem to make a bit of noise which seems to reduce as pressure builds in the tank.

Belt drive compressors live longer due to the lower revs, my 3hp is a lot quieter than my old direct drive 2hp that wore the rings out.. Mind you the 100litre tank is bigger than you bargain for.

Norm

The Burisch is a "badge job". Same compressor from same factory can be got with various stickers on eg Wolf, Wold, Dakota and others according to internet searches.

I'd not touch with a barge. It will be pretty loud but the big no-no for me is that the 14 cfm is displacement rating derived directly from the swept volume. General rule of thumb is that actual Free Air Delivery is around 2/3 rds displacement rating at 100 (and a bit) psi. Odds are the best FAD you will see is going to be about 9 cfm. Selling it as 14 cfm is plain dishonest.

On similar things I've seen the motor is an inexpensive 2,800 rpm jobbie rated by input power not output power. Often rather inefficient to boot although at least the truly horrible motors that were better at heating the workshop than turning things have disappeared over the last couple of decades. I once bought a so called 3 HP one to drive a compressor which turned out to have a 3 hp input power rating and, probably 1 hp output (if I was feeling generous) to drive a compressor. Full refund job!

To me the first question if contemplating spending serious money, like the £500 odd mentioned, on a compressor would be "why not hang on for a decent used Hydrovane". Hydrovanes are quiet, are built to industrial standards and last for many years if the oil is changed at the right intervals. The HV02, 3 hp, version gives you 7.9 cfm at 10 bar. When I switched from an Atlas Copco Vee twin, another proper industrial compressor, of theoretically the same rating to a HV02 I got more air from the Hydrovane letting me run my blast cabinet longer before running the tank down too far.

Single phase hydrovanes can be found. Alternatively they run really well off a VFD such as my favourite Eaton DE 1 series.

Clive

As always you get nowt for nowt. Good quality generally costs more than lesser examples. Look at the small print among the specifications is my advice. Then your choice.

My old two horse power (around 10cfm) using a cast iron two stage pump will outlast me. Cost about (possibly less than) thirty quid, and a non return valve, at a farm sale about 25 years ago. Receiver is stood on end and about 150 litres I would guess.

I periodically check the receiver, by hydraulic test,

Volume of air stored depends on pressure and some machines may only have intermittent-rated motors. Pressure switches are also an obvious item for skimping on quality. ‘DIY’ grade indicates to me as ‘not too long lived if used much’. Is simply buying a new compressor and motor an option? Even adding an extra receiver can tip the scales on what you need to spend.

Go to soft-start and you may be able to go to 5HP?

5hp on single phase should be achievable, worked years ago making high pressure washers with up to that on 13 amp with no trouble.

It’ll ‘drain the mains’ on initial start up, especially if on load. OK once up to speed, but may blow the plug top fuse occasionally?

You will almost certainly need a C curve MCB to run it, it will probably trip out a B curve on startup.

I've used a SIP Airmate, 3hp, 14cfm piston displacement, 50L receiver (100L available), direct drive, to supply air to my shot blast. I bought some 10 years ago for about £220, not much more than that now. Didn't think it would last long but its still going. I now frequently exceed the operating cycle for it (15mins), it may be a longer cycle now, would need to check that. I'm only using it occasionally, I think frequent use would soon cause it problems.

After every time its run I drain the receiver, change the oil now and again and check the filters, apart from that it gets no other attention.

It is quite noisy, I can put up with that for occasional use. With hindsight I would buy a belt driven compressor, cheaper replacement of the two main assemblies.

John