Compressor purchase

[tri-comp]

A couple of weeks ago I bought a Polaris 285 Compressor.
I believe that product name may be a proprietary name belonging to the Danish wholedealer from where it was purchased.
When selecting a compressor you should of course focus on capacity i.e. will it do the job ?
This one is a 3HP, 260 litre/min., 10 Bar type with a 20 litre storagetank so it will at least do any job I'm likely to throw at it.

There is ONE other parameter that is very important imho. and that's the noise-level.
Small compressors, smaller than this one, makes a tremendously loud, severely annoying and irritating noise when in use.
I didn't want to buy one that requires me to wear ear-protection each time I'm using it.
The one I ended up with allows for nearby conversation when in use, even if you do have to raise your voice some.
It's rated at 77dB in the add's but this can't be trusted.
The noise level is more likely somewhere around 85dB(A) which is still much lower than smaller compressors.
Not many sellers publish the noise level and when they do, it's quoted way too low to be realistic.

[Radio Wrangler]

2-pole electric motors run at 2800 rpm and are cheaper to make than 4 pole 1400 rpm motors.

Direct drive compressors save on the cost of pulleys and belts, and the fast-revving compressor pump can be smaller in capacity for the same flow rate.

These things make for a noisy but cheap compressor.

If you want something quiet and longer-lived, you have to look at larger, belt-drive machines. The slower revs and larger cylinders mean lower velocities and smaller distances travelled for the piston rings.

Air receivers, the storage tanks are now made of higher strength steels and can be thinner, lighter and cheaper than their predecessors. Draining condensed water from the tank needs to be done diligently as a result because any corrosion is more serious than with old thick tanks.

For light use, a small noisy lightweight machine ought to be fine, but be sure to drain frequently. If you want to use it more frequently then a larger low-revving machine is much better if you have the space.

Once you've got compressed air, you find a lot of uses for it. As said earlier, there are some amazing air operated tools. A spot-blasting gun or a small high speed die grinder can work wonders. Spot isn't a typo for shot, by the way, and a turbine die grinder makes a Dremel look like a toy.

David

[stevehertz]

Is it clear how to drain these things? Will the compressor come with instructions how to do it? What is the basic procedure and how often? Cheers.

[Radio Wrangler]

There will be a drain valve at the lowest part of the tank.

With pressure in the thing you just open the little valve a turn or two and the water is blasted out. Do this whenever you finish using it so you don't leave it wet. Close the valve.

David

[Peter.N.]

In the 'olden days' we used fridge compressors which had a separate motor, they would deliver quite a high pressure but with very little volume so a large receiver was required but still managed to use them for spraying but you had to stop and wait for the pressure to build.

Peter

[stevehertz]

I've ordered it, delivery tomorrow 13 feb. I'll report back in due course. Meanwhile, as I understand it there's different connector type options - should I choose a particular one? On that score, doesn't the compressor have a connection point that already determines this choice?

[chriswood1900]

Most compressors use a standard threaded connection on hoses (I think 1/4" BSP) and you can do up and undo them as required, this is however very inconvenient so most regular users use on of the quick release type connectors, my preference is for this type
https://www.screwfix.com/p/pcl-aca25...e-thread/5763h
as per my earlier post,cheap and readily available..
Chris

[Radio Wrangler]

Those are good ones.

THe female connector has an integral valve, so they go on the air supply side of things. Inserting the male connector opens the valve, which can take a good push. Sliding the release ring on the female connector fires the male end out witha bit of force and the stored air in the pipe.

There are cheaper versions but not all are compatible. Stick to proper PCL ones.

David

[Sinewave]

One thing to bare in mind with a lot of these small compressors is the 'l/pm' or 'CFM' required by tools is the free air delivery. Most compressors give a CFM for the pump, but that is not the free air delivery. FAD is usually about two thirds of the pump FAD.

So if you have a 24l compressor which is perfectly adaquate for blowing down and tyre inflating, the FAD will usually be around under 5 CFM - the label saying 7 CFM is the displacement of the pump, not the free air delivery.

[poppydog]

A in-line filter or one that screws into your regulator would be a good idea. This will help to keep your air a bit drier so you don't end up pressure washing delicate items.
regards poppydog

[stevehertz]

Thanks everyone. So what type of connector will the Impax have? Can anyone tell from the photo or even the info - I can't see it myself. Cheers.

https://www.screwfix.com/p/impax-om2...v?activeTab=rr

[chriswood1900]

It is impossible to tell from the pictures and as you found its not in the specification anywhere, it looks as though it could be PCL taper or XF I think you'll have to wait until it arrives and see. However, it will almost certainly still screw onto a 1/4" BSP fitting so if you opt for one other other you could change it to your preference.
Chris

[G6Tanuki]

I was always taught to "blow down" a compressor [open the drain valve] at the end of the working day, and leave the drain-valve open. That way you get the maximum amount of condensate out of the tank.

[ms660]

What type of connector does it have.....Am I missing something here?

Lawrence.

[duncanlowe]

You do need to be careful when disconnecting air lines. You can end up with the connector whipping around. In most workplaces they insist on using special connectors that release the air pressure before being able to physically remove them. I use PCL but have nearly been caught this way a couple of time so might upgrade one day.

[Sinewave]

I never empty my compressors of air, as that's a waste of energy. I drain the condensate before use, as the temperatures overnight etc can build up condensation, as well as the affects of warmer air entering the receiver.

I also have a small whip hose with a quarter turn tap to shut the air off to the tools, so I pull the trigger to discharge the tool and line before disconnecting the hose. Either that or on a regulated output, shut the regulator down which will discharge the line of air.

[stevehertz]

Originally Posted by duncanlowe

You do need to be careful when disconnecting air lines. You can end up with the connector whipping around. In most workplaces they insist on using special connectors that release the air pressure before being able to physically remove them. I use PCL but have nearly been caught this way a couple of time so might upgrade one day.

Are you saying PCL components do not include the special connectors that you mention?

[Boater Sam]

Always used PCL in the garages, they don't leak or wear like some types. The residual air in the line can cause it to fly, but its just common sense to use two hands, one on the hose, one to release the PCL.
Its worse with cheap underrated rubber hose that blows up like a long balloon, good hose is much better, or for what you are doing, nylon single skin tubing will be fine up to 120 psi but don't kink it badly.

[Radio Wrangler]

I have a filter feeding a regulator which splits to two PCL fittings. One via an oiler. For power tools like die grinders and drills, you should use oily air. For painting, that's the last thing you want. So you have to be careful to have two hoses and to keep one strictly for clean air, the other for oily air.

For light use, you can get by with remembering to squirt the odd shot of oil into the tool.

Another bit of compressed air kit is an Aga vacuum generator for a serious desoldering station.

Once you have compressed air, the uses are surprising.

David

[stevehertz]

The connector hoses seem to come with just a threaded connector at each end. Is there a convention as to what gender connectors you fit to hoses and components? For example would you fit male PCLs to both ends of the hose, and then use female PCL connectors to the compressor and tools (or vice versa), or, do you fit male and female connectors 'in line', kinda like aerial convention where you have the male connector pointing in the direction of 'flow'? Indeed is there a convention, or does everyone just fit connectors willy nilly, as they wish, ie to no convention?! I'm thinking that's the case!