Air Compressors - what to buy?

Discussion in 'Workbenches, including workshop techniques.' started by Focalplane, 29 September 2020.

  1. Focalplane

    Focalplane Western Thunderer

    I have two air compressors but research shows that the size and type of an air compressor needs to be matched to its potential uses. Research on youtube is usually aimed at English language users and those familiar with Imperial measurements. So terms like CFM (cubic feet per minute) and PSI (pounds per square inch) will be thrown about. Here in France, where I am writing this, everything is in metric, so CFM becomes Litres per Minute or Second, PSI becomes Bar. One aspect that doesn’t change is HP, at least it only changes, in French, to CV. But horse power ratings aren’t always what they seem.

    So, one thing I have learned is that, generally, bigger is better. Though this rule only really applies when considering applications that require large, continuous volumes of air to be delivered with little or no drop in pressure.

    So what are the various applications in order of increasing power and volume requirements?

    The tool department at Leroy Merlin came to my help the other day with this scale, though it is really focussed on the high end:

    100L/min, 1.5 cv, 6L tank, suitable for inflating tyres, balls, spraying degreasers and insecticides. This would also include simple air blasting/dusting.

    120L/min, 2 cv, 15-50L tank, suitable for the above plus painting small areas. Small areas would include our model projects.

    150L/min, 2 cv, 50L tank, lightweight sanding tools that are likely to be run more continuously. Also air tools requiring high torque.

    250L/min, 3 cv, 100L tank, painting large surfaces, including houses and vehicles

    300L/min, 3cv, 150L tank, Wood and metal stripping, de-rusting, sand blasting.

    Some observations,

    First, the tank pressure may be higher than the application pressure which can be easily set on many compressors or with the addition of a “choke” in line. Having a higher pressure in the tank simply means a more continuous flow of air can be maintained at constant working pressure.

    Second, if portability is a requirement then a smaller compressor works just as well as long as it can keep up with the application. Some airbrush compressors do not even have a tank. However on a long “blast” the pressure may fall below the optimum level with potential poor results.

    Third, noise can be a problem if using the compressor in a confined space.

    In assessing my own needs, it would appear that I might be best served by buying a 250L/min compressor but hang on to my much smaller 100L/min unit with a 6 litre tank. The large unit would be primarily for house and car painting, not exactly what most Western Thunderers are requiring.

    I would be interested to learn what others’ experiences are in crossing the air compressor minefield. My mind is very much open to what others have experienced. I should add that I grew up in an environment that included a 12 booth spray shop and an electrostatic spray machine. But I was dissuaded from having any future in the business so became a geologist!
     
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  2. simond

    simond Western Thunderer

    Paul,

    at one end of the scale I have a cheap (though not particularly nasty) diaphragm compressor under my workbench, which does most of what I need with the airbrush. It is quite noisy and doesn’t have a tank or a pressure switch. I keep promising myself something better but Manana, manana... I have it connected to a coil of copper tube which acts as a tank/ condenser and smooths the pulsing out a bit.


    upload_2020-9-29_21-3-28.jpeg

    At the other end of the scale, at work we have a couple of Hydrovane HV02 compressors, which together are big enough to supply 4 CNC machine tools, and half a dozen blowguns - but, using the air wrench can get them both running, meaning that it’s using more air than one can continuously supply.


    upload_2020-9-29_21-16-35.jpeg

    2.2 kW, 10 bar, 230 litre/min 75 litre, about £2000 new. Well happy with these. Got one on eBay for £600 but needed new contractors, less than £100.


    Hth
    Simon
     
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  3. Mike Garwood

    Mike Garwood Western Thunderer

    I use the Iwata C-IW-PLITE. Not cheap, but does everything that I need. Sprays Cellulose (with HVLP), enamels and acrylics. Doesn't have a reservior - I've never seen a need for one - but does have the moisture trap. The thing I most like about it, is the size. Fits under my desk and is very quiet. No where near any of the sizes you've described. So this info may be completely redundant.

    Stay safe

    Mike
     
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  4. simond

    simond Western Thunderer

    Hi Mike,

    does your compressor look like this inside the cowl?

    upload_2020-9-29_21-41-46.jpeg

    cheers
    Simon
     
  5. LarryG

    LarryG Western Thunderer

    My own set up which my father bought me s/h in 1969 is permanent and is a a 3/4 horsepower motor driving a compressor via a Renault fan belt. It feeds to two ex Calor Gas bottles bolted together to form a large storage tank. The safety valve is about the size of a loco whistle! So I borrow PhilH's portable compressor when spraying anything in the layout shed. It's pretty neat with a reservoir and adjustable pressure outlet and cost less than £200.00.

    Looking at the innards in Simmonds post, it has a resemblance to Phil's. I recognize the pressure adjuster above the water trap. I will point him in the direction of this thread in the morning.
     
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  6. michl080

    michl080 Western Thunderer

    Paul,

    I checked the Leroy Merlin site and found the compressor above, it is likely https://www.leroymerlin.fr/v3/p/produits/compresseur-de-chantier-first-air-15-l-2-cv-e1400751463 this one.

    It is not stated in the technical description, but one of the photos reveals that it is running at 95db. You wouldn't want to have that anywhere in the house, not even in the basement, Ithink the only place would be a shed or garage.

    Unfortunately, bigger is not only better, but als louder. :)

    Michael
     
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  7. Steph Dale

    Steph Dale Western Thunderer

    95dB!?!! That's bonkers; right on the cusp of permanent hearing damage!

    Steph
     
  8. Focalplane

    Focalplane Western Thunderer

    Michael

    The compressor I currently have cost double and has a low sound rating. It situated in my workshop but has been moved around the house as well. I am not sure what the db rating is. It is currently available on line and I saw one on the shelf on Monday morning. Price around € 140. I would recommend it for most modelling but the tank capacity is too small for larger jobs at only 6 litres.

    image.jpg

    As LarryG suggests, it is always possible to add a larger tank in series with the compressor.

    This unit looks to be a match for larger projects and also has a small footprint for its capacity.

    https://www.leroymerlin.fr/v3/p/pro...e-100-l-2-5hp-vertical-century-m82689774.html
     
    Last edited: 30 September 2020
  9. Focalplane

    Focalplane Western Thunderer

  10. michl080

    michl080 Western Thunderer

    The picture on the site shows a sticker saying 59db. This is quite a difference to 95db :)

    Michael
     
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  11. simond

    simond Western Thunderer

    another vote for Leroy Merlin.

    then again, it clearly has two cylinders and claims (twice) to have only one!

    that said, at 6 litres, 0.5cv, 59dB and £130 or thereabouts, manana may become aujourd'hui next time we cross the channel, as it will do the car and bike tyres and the airbrush. Madame will assert, yet again, that I've taken leave of my senses, but she's getting used to that after all these years.

    thx
    Simon
     
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  12. Lancastrian

    Lancastrian Western Thunderer

  13. PhilH

    PhilH Western Thunderer

    Paul,
    This is the compressor that Larry refers to:
    Sparmax%20TC%2d610H%20Plus%20Airbrush%20Compressor

    It was £185 when I bought mine in April, but postage was free. At that time Air-craft were the cheapest supplier of that model. It has a tank, pressure gauge, moisture trap and two outlets. Its also reasonably quiet.

    Philip
     
  14. Focalplane

    Focalplane Western Thunderer

    I have yet to mention my Sparmax 510, a similar but earlier model without the cover. Also good for small jobs.

    image.jpg

    It cost £100 from a Hobby Shop in Solihull, now closed down, I think, or at least no longer selling such equipment.

    Paul
     
  15. Ian_C

    Ian_C Western Thunderer

    For model work my recommendation is a Sparmax TC-610. Mine came from airbrushes.com, a very helpful and friendly bunch. Comes complete with pressure regulator and moisture trap. It's also a pressure cut off type, that stops running when the tank reaches a set pressure. This a 'good thing' because it saves energy and compressor duty cycle, and it makes no noise when it isn't running. Runs up to 60 psi and claims to be 53dB(A). It's certainly quiet enough to work around without annoyance or hearing protection.
    Sparmax TC-610H Limited Edition RUST Compressor
     
  16. simond

    simond Western Thunderer

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  17. Focalplane

    Focalplane Western Thunderer

    An additional comment about Scheppach products. A very Germanic name but quality is not their strength. Personally I would steer clear of their compressors if they are like their other products. One thing that can pay dividends is to look at the returns in the customer service area of your local store!
     
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  18. Focalplane

    Focalplane Western Thunderer

    As a follow up to this thread I just discovered a “new” range of compressors sold by a British company, SGS Engineering. I have no connection with the company but I do like what I see and may invest in the 50 litre model for car spraying. What is more, they have useful guides to selecting equipment and to a lesser degree techniques.

    How To Set Up An Air Compressor for Spray Guns & Painting | SGS / Help & Advice

    Much of their range seems to be sold out or coming soon. They do have smaller compressors as well, suitable for airbrush work.
     
  19. Mudhen

    Mudhen Western Thunderer

    I've had a Bambi compressor for 24 years and would highly recommend it. Not cheap but great support. A couple of years ago I needed a need pressure switch, got good advice on the phone together with fitting instructions, immediate supply and with me in a couple of days.

    BAMBI Air Compressors | Air Supplies™ UK

    all the best
    Tim
     
  20. adrian

    adrian Flying Squad

    One note of caution though with the small SGS compressors

    Screenshot 2021-02-07 at 13.04.35.png

    For reference, note the Bambi compressors referenced by Tim - spec for those says 40dB.

    Screenshot 2021-02-07 at 13.03.10.png
     
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