Electric Air Compressor (for Model A Jobs)

[Hoogah]

Looking for advice from the wise heads here!

I'm looking at buying a S/H air compressor, having gone down this path because I want to back flush my engine and radiator, and have read here that some compressed air is a help with this process). However, in the future I may want to use a compressor for media blasting and spraypainting.

The unit that I have seen for sale locally is in the photo. This one is for sale at $70, about what I'd have to pay for a day's hire, so you can see what my brain is telling me. It is a Peerless; it's Australian made so won't mean that much to anyone UpOver! It also looks a bit rough.

We are on single phase power and I guess I'd prefer an electric motor for simplicity.

However, I am an air compressor nuf nuf, so what should I be looking for as minimum specs to do the sort of jobs that a bloke with a Model A Ford needs to do?

- Tank size
- Free air delivery (which seems to be quoted here as litres/min at 100psi. What a strange mix of metric and imperial!)*
- Motor HP
- Max PSI
- Amps Draw
- Drive (Direct vs Belt)
- Pump construction (Cast vs Alloy)
- Pump RPM (I've read that slower is better/more efficient)
- Pump cylinders (1 or 2)

I'm ready . . . . blow me away!

* Is that US gallons per cubic acre in the US?!

[tinkirk]

i can tell you that one won't do the job
bigger is always better
T.N.

[SeaSlugs]

if you want sandblasting capabilities you need one heck of a compressor and tank and cfm. that little compressor above wouldn't run an impact wrench.

spraypainting doesnt require a whole lot of air but you want consitent air.

[chap52]

The more "cfm's" the better. Low cfm rating means that the compressor will not hold constant high pressure. I have one that has a 30 gal tank and is rated at 8.4 cfm @ 40 psi and 6.4 cfm @ 90psi. It will handle most projects but is a bit weak with impact tools at high torque.
Worked fine for painting but had to recycle a lot at higher pressures.

[California Travieso]

If you want to flush your radiator and block people here have recommended a sump pump or pool pump. I used a sump pump to drain my pool and it put out quite a lot of pressure. I'm not at home so I can't check the output now. I got mine for a good price at a local hardware store.

David Serrano

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Martin,

The compressor your showing will be fine for airing up tires or running a small air tool such as a pneumatic ratchet. It will not do the job for sand blasting. You would be better off with a much bigger compressor. I have one similar to the picture I posted. Mine is 60 gallons and I can blast all day with my Harbor Freight cabinet and never go low on air. Cost's $$ though.
To add air to back flush your radiator you don't need super long bursts of air. You would probably be able to get by with a good size air bubble tank and add blasts of air to your water flush with that. You may need to refill it a few times until you are satisfied.

[Tom Wesenberg]

I would never buy any oiless compressor, nor a one cylinder direct drive compressor.

I can sandblast with my older Wards 2 cylinder single stage 110 volt compressor, but it runs stead to maintain 40 PSI at the nozzle. It's OK for short jobs, but a 2 stage 220 volt compressor is best for blasting.

[40 Deluxe]

Try to find a used commercial unit that has been hydrostatically tested, or do it yourself. It's easy. Remove a line or fitting from the top of the tank, fill with water and use a hand pump (like a new grease gun filled with water). Add a gauge and pump up to the PSI listed on the tank. Since water doesn't compress or expand, if the tank fails it just dumps water on your feet. A few years ago I bought an old gas station compressor with a burned out motor for $200. It had an almost new two stage pump on it. I found an identical new motor for about $250. Pick a good spot for it as you have to bolt it down.

[wingski]

Hoogah, are you running six or twelve volts in your A? Let me know because if you’re running 12, there’s a photo of what I’ve got that I will send you.

Mike

[Hoogah]

Some good advice received so far, thank you!

What’s a 2 stage pump?

Wingski, I’m running 12v.

[jimjordan2]

Not considering sand blasting, others have already said what is needed for that, the compressor you are looking at, would do many of the small jobs around the shop. No, not a great system, but if the price is in line of what you can afford, and it actually runs and shuts off when full, and holds air. Why not?
This looks like it would do a much better than no compressor.
Just my frugal thoughts.

[SeaSlugs]

Originally Posted by Tom Wesenberg

I would never buy any oiless compressor, nor a one cylinder direct drive compressor.

I can sandblast with my older Wards 2 cylinder single stage 110 volt compressor, but it runs stead to maintain 40 PSI at the nozzle. It's OK for short jobs, but a 2 stage 220 volt compressor is best for blasting.

agreed on the oil filled compressor. Direct drive work OK but usually slow and like my last one when the motor burns up your up a creek. Oil filed can last many many years IF you do the proper maintenance and change the oil yearly (or by hours).

One thign to note - compressors do not like cold weather so i dont know what temps do in upside down land but here my oil compressor refuses to run when its single digits.

[eagle]

For a sanblaster of a decent size, 15 CFM is minimum. I use an 1/8 inch nozzle blaster at about 40 to 80 lbs air pressure and my compressor will just barely keep up. Of course, a smaller nozzle will reduce the required CFM but will also make the job take longer. Read this : http://www.hironsmemorials.com/Blast...tion_Guide.pdf

[Tom Wesenberg]

Originally Posted by Hoogah

Some good advice received so far, thank you!

What’s a 2 stage pump?

Wingski, I’m running 12v.

Air is first compressed in one larger cylinder, then pumped into the smaller higher pressure cylinder, and then into the tank. I've also seen home and shop 3 cylinder, 3 stage compressors.

[Hoogah]

Well, with a bit more research, I've discovered the following about the compressor pictured in Post #1:

45 litre (12 US gallon) tank, 175 litre/min (6 CFM), Max Pressure 145 psi
Motor 2.5 HP, Single Cylinder Direct Drive Pump, 2850 RPM

Seems to have features and specs that don't measure up to expectations for quite a few of you guys?

Is the bad thing about single cylinder pumps mainly about the RPM that they need to work at, and resulting inefficiency? Belt drive pumps seem to run at 1/3 to 1/2 this speed.

[Corley]

Get in good with the building maintenance guy at some larger buildings. Most have pretty large compressors which they replace on a shedule, not when there is a problem. I got mine for free, it actually has 2 compressors on one 100 gallon tank, each having 3 cylinders, with two 5hp motors. They were about to throw it in a dumpster when I noticed it and backed my truck up to the dock. It even came with a refrigerated dried unit to dry the air. The building was mostly offices, so it had very low usage, and looked like new. Price, $0.00

[Wick]

This set up works. GO get Two of the 5hp 60gal 220v ones. Less then $500 each. Tie them together and valve both in when blasting. You can run anything with twick the cfms and for under a grand.
Tom is western Va turned me on to this.

[BILL WILLIAMSON]

I just found one that looked BIG enough & the PRICE was RIGHT & BOUGHT it!
Bill W.

[Russ/40]

At the beginning of my 29 restoration project I went to Lowes and purchased the following. It has fulfilled all my needs. The unit was $800. 14.1cfm @ 140 PSI, 16cfm @90psi, 80gallon, 2 cylinder, 230 volt, single phase, 20 amps. I used it for extensive sand blasting, for cabinet bead blasting, blowing off petroleum cleaned parts, and for all paint, and buffing work with various air tools. I never felt i needed anything more.

[CarlG]

I don't do any blasting or painting, so my DeWalt air compressor I bought at Home Depot does the trick for me. Small footprint in a cramped garage.