Thread: Compressors

You may have trouble running the ratchet and rattle gun on these small compressors as they usually require a fair volume of air to make them work.

So is there much difference in performance between a 20L tank and a 35L tank - the numbers are almost double but does that equate to almost double performance?
Cheers
Smidsy

It is not so much as the capacity of the tank but it certainly helps . It is more the compressor pump being able to keep up with the volume of air required by the guns, You find some tools use a large volume of air quickley and the pump struggles to keep up with the usage so it keeps cycling until you stop using the tool and it fills the tank again.

So from what you're saying, would be right in thinking that if two compressors are of a similiar HP & CFM rating the smaller tank would actually be better based on the ability of the compressor to keep it full?
Smidsy

I ahve been doing some research in this area myself and have found that the 2.5 HP may just cut the grade, what is important when you are purchasing this size compressor is the Free air delivery recommendation and check this say against the tool that would use the most air in your case the rachet. The store should be able to provide you with this figure. This size compressor will struggle to handle any air tool that has long work cylces such as a planner, sander or grinder.

Also the direct drive compressors produce more noise than the belts.

By free air delivery, I take you mean the litres of air per minute that it delivers?
Smidsy

Hi Smidsy,
if you want to use air tools,eg rattle gun you'd be wasting your time on a small unit,a 15 or 17 should suit your needs,you will regret going smaller,there is usually some units like these in the Quokka good luck

These days compressors especially cheapos seemed to be sold on the size of the tank, and not the size of the compressor.

I guess there is some correlation, ie, smaller tank = smaller compressor.

A far better guide is the cfm rating, (cubic feet per minute), but don't jump too far ahead, this is actually a calculation of the displacement of the compressor. A poor quality (cheap?) compressor will have a shorter piston stroke, and a good quality (dearer?) one a longer stroke. Both may have the same cfm, but the better one will deliver more air.

Good quality compressors will give the free air delivery, ie the actual amount of air pumped per minute.

From experience, a 10cfm compressor, (displacement) will deliver about 5-7 cfm of air. Most "tools" ie rattle guns, sanders etc, need about 25 - 30 % more air to run them effectively than the manufacturer suggests, its a bit like minimum pc requirements for running a program.

Most "tools" are fairly inefficient at turning electricity into energy at the coal face, normal hand held tools are heaps better.

An 8cfm compressor will quite adequately pump up tires, and a kero gun. I own a top end 15cfm compressor (12 cfm free delivey?) and don't have drills, planers, sanders etc. for it, I don't think it's worth it.

Bigger tank = gooder, It simply acts as a storage area, so whilst you aren't actually pulling the trigger or whatever, the compressor is tucking a little air aside for when you do.

Hope this helps and doesn't confuse.

Hei Guys,
After trudging round Supercheap and a few other places I ended up going with the mitre 10 house brand for $159 - 2.5HP and a 24L tank.
The thing that put this one over the rest was the output rating of 294 litres per minute - this compares with 206 for the GMC which was about average.
I would have liked a bigger tank, but only one in my budget had a 40L tank but was only rated at 220L per minute and I figured I'd spend half my time waiting for the sucker to fill.

Thanks for all the advice.
Cheers
Smidsy