How cheap can compressors get?

A couple of blog entries ago I suggested that a compressor is a dandy trinket to get someone for Christmas. I said they were becoming very inexpensive.

This is what I meant. These pics are scans of ads for compressors in a local store, and are available at these prices in late November 2008.

compressors for sale

If you’ve a hankering to get into the game…using compressed air in your home workshop I mean…it’s hard to beat prices like these.

If you do decide to buy, make sure you find out from the store where you take that particular compressor for warranty repair work…and if you need to get it repaired after warranty, who does the repairs for them?

It will save you a lot of searching down the road when these electro/mechanical devices ultimately fail.

Here’s lots of info on using compressed air.

Venturi (compressed air driven) vacuum very effective

I’ve long been planning to write an article or two on venturi vacuum devices for www.about-air-compressors.com. Haven’t got it done yet.

Besides pulling a vacuum for almost any application, a venturi vacuum device also has the ability to pass material through itself. Since there’s no moving parts, and the only thing flowing through the wide mouth of the unit is air, if material small enough to fit through the device becomes entrained in the air flow, it passes through the vacuum device with no problem.

One of the leading companies manufacturing such devices (among many others) is Exair.

If you’re looking for an interesting use for venturi vacuum, here’s an article about a Compact, powerful vacuum for chips and other dry materials that might be of interest.

A compressor for Christmas?

Why not? There’s a huge array of low cost DIY home workshop compressors available throughout North America these days. Probably the rest of the world too, though I haven’t travelled off continent lately.

It seems for under $200 you can get a compressor and a combi-kit containing all manner of accessories and tools for the compressor.

Do you need a compressor? Yup! Absolutely? Well maybe not an absolute necessity. But once you’ve got one, you’ll find all sorts of uses for compressed air, and they really are a handy device.

One thing you must understand. No home workshop DIY type air compressor running on 120 VAC power can deliver enough compressed air fast enough for you to run air tools for more than a short time before your unit runs out of air.

So what?

When you’re working at home, there’s no assembly-line-pressure. You just put down the tool and do something else for the minute or so that it will take your compressor to come back up to cut-out pressure and to stop again.

Either found under my tree, or in an envelope (in the form of a purpose-specific gift certificate) it’s a Christmas gift that keeps on giving, for years after the lucky recipient received it.

If you get one for Christmas, here’s where you can find lots of information on using compressors.

Make sure your sprinklers are empty!

It’s the time of the year when you have to make sure that all of your sprinkler lines are void of water.

Water increases in volume as it nears the freezing point, and this volume increase means burst lines, broken valves etc. if there is water in your sprinkler lines and it freezes.

Thanks to Mike Higgins of Grand Junction Pipe & Supply in Grand Junction Colorado who tells us…

“The following equation should be used to figure out the proper volume of air needed for your system. The size of the compressor needed should be based on this equation. This is based on Cubic Feet per Minute (CFM’s) and the Gallons Per Minute (GPM’s) for which your system is designed.”

If you take the GPM of your system, and divide it by 7.5 it equals the CFM you’ll need to push the water out.

Mike goes on to say that if your system flows 20 GPM of water at 30 PSI, then you divide the 20 GPM by 7.5 to get the CFM necessary to adequately blow out your lines. In this case the answer is 2.66 CFM, so you’ll need a compressor able to provide that flow of 2.66 CFM at 30 PSI to get all the water out.

The rule of thumb for compressors (more info on compressors here) is that for each HP of electric motor (over 10 HP) you’ll generate about 4 CFM of flow at 90 PSI. Under 10 HP I use 2.5 CFM @90 PSI for each HP of electric motor, as my rule of thumb.