Air tools and compressor?

when my neighbors basement was flooding, i lent him my sump pump, hose, extension cord and wet vac. he never thanked me, gave them back, or even mentioned it again.

 

Water is more of a nuisance than you might expect. There's a lot of it in air. There's more if you put more air in a small space. Then it shortens the life of your tank and your tools. So managing the water makes the whole compressor-ownership picture more complicated. Systems for removing water from the lines and tools range from fairly cheap and less effective, to expensive, bulky, and only suited for permanent installations.

It would be convenient to just have a compressor and air pumped up at all times, to just use some air when you want and have it top back up. But instead (unless you have a high-end system with fancy drain valves), you probably end up emptying the tank every time you're done with it, hoping to get most of the water out, and then having to twiddle your thumbs waiting for it to fill every time you want some air.

Trying to empty an air tank quickly always takes longer than you think, because the expanding air cools, and the water keeps freezing and blocking the outlet, then thawing and flowing again, then freezing again ....

Steel tanks for carrying compressed air around have a mandatory seven-year discard date (in the US anyway) because of the issue of water and internal rusting that you can't detect. My steel tank will expire this fall, after seven years on which I've probably not used it for more than a dozen jobs. So for light anticipated usage, there's a real practicality question to be weighed.

On the other hand, you can buy aluminum tanks that don't rust.

When comparison shopping, you want to compare the air flow rate the compressors are able to produce at a certain output pressure; sometimes they won't be specified at the same pressure, and you have to convert. When the flow is given in SCFM (a standard defined measurement), you can make comparisons, assuming the ratings are honest. If they are given in "CFM" (without the S), too much is unspecified and the manufacturers can pretty much come up with whatever number they want. In the US at least, where that has been a bit of a scandal plaguing the industry. In Canada, perhaps they don't use cubic feet or minutes at all, and there may even be stronger regulation of how those numbers are advertised.

Air pressure drops through hose and fittings just as voltage drops through wiring, more drop with more flow. Depending on the hose length and fittings between your regulator and your tool, when the tool's in operation it may be getting a much lower pressure than you've set the regulator for. That's something to think about in planning your hose and fittings. The quick-disconnect couplings are convenient, but the most common design has a big spring-loaded pintle right smack in the airflow, and is a big source of pressure drop, especially if you've connected a few in series. There are various kinds of high-flow or unobstructed couplings, but harder to find.

Just as compressor makers are tempted to overstate their flow capacities, air tool makers are tempted to understate their tools' flow demands. If you're looking at an impact wrench's CFM requirement, for example, and thinking "oh, that's easily within the capacity of this compressor here", beware that the wrench's rating may be an average over time, with the assumption you only pull the trigger a few seconds at a time. Its actual air consumption under load may be several times what you think. It seems typical that the tools that give the most bang for their airflow demand, and therefore are most practical to use if your compressor isn't huge, are the major-name and more expensive tools.

For light use, you can totally get away with using a technically-undersized compressor for the airflow demand of the tool you're using, as long as you have the patience to work in short bursts and wait for the tank to refill. In this case especially, you may want to oversize your hose, pay extra attention to minimizing couplings or using high-flow types, because you're trying to keep pressure drop reasonable even at higher flows than such a compressor would normally be designed for.

That's about all I've got....

-Chap

 

now i'm wondering about my old compressor steel tank. i had no idea there was a 7 year rule. don't recall reading about that in the o/m.

 

Yeah, I don't think there was any such note about the tank on my compressor, either. The rule seems to be for the portable tanks you can fill with air and carry around. I had bought one of those when I was thinking I might do my own re-roof, and leave the heavy compressor on land, and a hose up to a tank on the roof, nearer the tool for less pressure drop.

I don't know why there's such a rule for portable tanks, and not for those integrated into compressors, when both are steel ... maybe the integrated ones are just specified to be heavier gauge, or the compressor is expected to wear out mechanically before the tank is bad ... who knows.

Anyway, the lifespan limit on steel portable tanks was one of the things I didn't know about at the time I went out and bought one. Those are the things I tried to mention here.

More recently, I've been very happy with the four gallon portable aluminum tank I picked up to replace the steel one. Not only will I not have to scrap it in seven years, it's far lighter. I can casually one-hand it, just nicer all around.

My only air tools so far are one impact wrench, one hammer, and a cheap caulk gun. I haven't used any of them often, but boy are they nice when the time comes.

The caulk gun was a no-name from Menards; for the impact wrench and hammer I went with Ingersoll, though more expensive, because the cheaper ones seemed less frugal with air, and I wanted to be able to work with a small compressor. I can happily do some useful work with the impact wrench, the four gallon aluminum tank, and the little 2-ish CFM Viair compressor wired into the car ... again, as long as I don't mind taking frequent breaks for the tank to top up.

I have some masonry work on my porch coming up, and I think I'll be very grateful for the hammer before I'm done.

All of these things have electric equivalents now, if all the travails of compressor management feel off-putting. The electric versions of the tools themselves tend to be more expensive, but then, there's no compressor to buy or deal with. They're also heavier. I carved into some brickwork with an electric Boschhammer rented from Ace Hardware several years ago, worked great, but that thing's around 25 pounds. The Ingersoll hammer whacks about as hard and weighs four pounds.

As for the caulk gun, there seem to be two styles. My cheap one just puts the cartridge in a sealed tube and lets air in the back, which is really simple and works great until the disk in the bottom of the caulk cartridge goes sideways and lets the air bubble right through the caulk. I've seen a different design where an air motor mechanically pushes, and that's obviously better, though I don't know how much more it costs.

-Chap

 

As I re-read your post, I think of that particular application as one that might look sweet but that I personally would never, ever do, unless in the process of replacing the hub bearing anyway. Shock-loading the bearing balls against the races by air hammer vibration would be something I'd want to avoid. If I had to do it, I might use something like a shallow socket on the hammer end (to keep it on the stud) and spin the hub around while hammering, so as not to shock the balls and races repeatedly in the same positions. But if I remember right, the tool advocated by Toyota for that job in the repair manual is an ordinary threaded puller, smoothly shoving the stud out with no shock to the bearing at all.

-Chap

 

Another interesting example of the tradeoffs involved. Comparing this to, say, an Ingersoll 231C, the weight difference isn't as huge as in my hammer example ... the Ingersoll is about 0.8 pounds (12%) lighter, whacks roughly twice as hard, and seems on sale this week for about half as much.

... but needs a compressor, and hoses, and and and and ....

-Chap

 

I have had my Black Max from Sam's club 20 gal portable 220vac unit since 1991. Used Prolong additive in the oil. Only problem was the high pressure aluminum tube cracked eventually and had to be replaced other than a couple belt tightenings. Do not get oilless ones they are crap designed and almost louder that a jet engine. Get one that is much higher CFM rated than you think you will ever need as eventually that air orbital sander or something high consuming will be useless if not. Most in the $ 750 range get close to running most tools. Only thing I did to extend tank life was keep the talk water drain valve barely cracked open so when it has pressure in it it just barely eeks out the water slowly.

LG-H918 ?

 

Before I sold out and moved, I had a "decent system" built around a twin cylinder oil sump compressor.
It was good for things like removing tractor tires.

I no longer have anything like tractors to work on.
After going through a couple of cheap Harbor Freight compressors just pumping up tires, I
got a Kobalt 8 gallon 1.8 HP model from Lowes. On sale I think it was about $130.
Shop Kobalt 8-Gallon Portable 150 Electric Horizontal Air Compressor at Lowes.com

It is an excellent unit for an "amateur" user and should power most any "light duty" tool you can get.
It does a fine job on 80 PSI RV tires and is overkill for most of what I do now.

And I have never had a serious problem with water. That only comes up if you use the compressor a lot, don't drain the tank often enough and/or do painting with it. A few drops of water going out through an impact wrench does.......nothing. Going into your tires it isn't a problem either. Spitting a drop of water out in the middle of a painting project can be a serious problem though.

I say: "GO FOR IT". But don't cheap out. You will be happy you did.

 

Like a lot of compressors in that price range, that one seems to be rated about 4 SCFM at 90 psi. That's not far from the average air demand figure for a 231C impact wrench (4.2). As I mentioned earlier, air tool makers love to give "average" CFM ratings, 4.2 in this case, based on the idea that on average, most of the time you're not pulling the trigger. The airflow of a 231C when you are pulling the trigger is 22 CFM.

That doesn't mean you can't use it effectively with a lower-rated compressor ... you'll just be drawing down the tank in those high-flow bursts, and waiting for it to recover. Again, to avoid pressure drop limiting the performance of the tool, you might want to select and size your hose and fittings more as if you were building a 22 CFM system than a 4 CFM one.

-Chap

 

Would like to add when I do paint I use a lower flow size wise touch up type gun and since we live in a terribly humid and swampy area I have installed a large industrial swirl type water separator on the compressor and two smaller automatic purging ones with quick disconnects inline at about 50 feet and 75 feet out mounted one low to a stump and one on a steel wheel rim and one plastic ball shaped media type disposable on the inlet of the gun where the air is much cooler by then that is very effective at keeping the dreaded water intrusion problems when painting.

LG-H918 ?

 

This is in leiu of an about $ 400 air compressor cooling/ seperator unit. Which is basically a refridgerator.

LG-H918 ?

 

That video was HILARIOUS, @Mendel Leisk.

I couldn't live without a compressor. But I mostly use it for cleanup and inflating stuff, so it's a small one. I can do almost everything else with electric tools and use less electricity and spend less time maintaining the equipment. And, my one car garage really doesn't have room for a compressor big enough to run air tools.

 

You consider $130 to be "prohibitively expensive" ??