Are those compressors any good?

With every weekend paper we get, we also receive a bunch of fliers from the big box stores, promoting their hardware, DIY supplies, and a broad range of air compressors.

The prices are sometimes really remarkable. So, can you really get a decent compressor, with an air tool or two, some fitting, air line and couplers for $159.00 + tax?

In a word….no.

What you will get though is an entry level compressor, accessories that will work, but sometimes for a very short time, and air tools that are meant for a few hours work every few weeks, not for production or commercial shops and so on.

But, for the DIY home shop usually this will be fine.

Listen, if you haven’t had a compressor before when you get one you’ll be amazed at how many uses you can find for it once the unit is sitting in your basement or garage calling out for you to come and play.

Nope, you won’t get a production tool or compressor, but you will get one that will be loads of fun to use, and might even last a few years if not used too aggressively…if you make sure you put the proper oil in the compressor and the right oil in the air tools. When I shingled my garage last summer, my little $179.00 – OK, I bought the expensive one – compressor chugged right along and made a major hammering project go much, much faster with the use of an air nailer.

Tips on compressors, plumbing, air tools etc. … is right here.

How much does air compress at 100 PSI?

Interesting question from a visitor recently.

As you sit there reading this, you are bathed in ambient air, standard air, which is about 14.7 PSI at sea level and at a specific temperature. The 14.7 is generally considered as one atmosphere, and you don’t notice it, given that you’ve been living and breathing air at that pressure since you were born.

The 14.7 PSI for one atmosphere will change slightly as the air temperature changes, depending on how high you are compared to sea level, and the relative humidity of the air. But for our purposes, and for most compressed air applications, 14.7 will suffice.

The air gage on your compressor shows zero, when the air pressure is really 14.7. It’s been adjusted to read that way. That’s known as PSI gage, as opposed to PSI actual.

Back to our question. If you end up with 100 PSI how much compression has taken place? Divide 100 by 14.7 and you get 6.8. That’s how many atmospheres have been squeezed into one cubic foot to achieve 100 PSI.

Looking for more information about understanding and using compressed air? Just click here.

“I canna’ do it, captain….I just don’t have the power”

With apologies for my bumbled quotation in the title to Scotty, crewmember of the Enterprise, from the old, old Star Trek TV series !

You know, I get a lot of questions on my ASK page about how it is that the compressors bundled with an assortment of tools and gadgets at the big box retail outlets don’t seem to have enough compressed air pressure or flow to drive the tools they are bundled with.

Aside from the commercial aspect….giving the buyer as little quality and quantity as possible in equipment to reduce cost and to ensure that the low selling price can actually make a profit, there’s another real reason.

North American homes commonly run on 120 VAC current and that is what is sent to the electrical outlets in your home workshop or garage. Your compressor is taking that 120 VAC current and changing into another energy form…compressed air.

Without getting into the formulas involved, there’s only so much power available in a 120 VAC line and the amount of power (or energy) available limits the size of the electric motor on your compressor, and that limits the amount of compressed air that can be generated by that compressor.

We all remember that “energy can neither be created or destroyed, it can only be changed.” When we fire up our compressor we change electricity into compressed air. Depending on the size of the electric motor and the compressor head and the flow and pressure required from it, it doesn’t take very long to max out on all the power available in a 120 VAC supply line. This limits the motor size, the compressor head size, and the output of the typical DIY home compressor.

In order to get more than 3 or 4 CFM at 90 PSI from a compressor, it’s going to have to be supplied with more power than a 120 VAC line can supply, which is why larger compressors are supplied with electricity at 220 VAC, 460 VAC or 575 VAC.

The more power available for the compressor motor and compressor head, the more compressed air you can get out the discharge port. It’s as simple (and complex) as that.

Another compressor recall….this one in Virginia

About 64,000 Strike Force model portable air compressors, all sold exclusively at Roanoke, Virginia-based Advance Auto Parts stores, and produced by All-Power America in California, have been recalled.

On these recalled units the air compressor motor could overheat and ignite the cover with the obvious result, a fire hazard. Also, the cover might not prevent internal components from being touched, posing an electrical-shock hazard.

No injuries have been reported, but there have been four fires reported.

The recall involves models sold at Advance Auto Parts stores and online from October 2006 through December 2007. They cost about $90. Consumers should stop using the affected air compressors and return them to any Advance Auto Parts store for a full refund.

This is the Advanced Auto Parts web site, and this one is All-Power America’s web site.

This web site is where you can get useful information about compressors, and using compressed air.

ISO 5388:1981

Did you know that there was an ISO standard for stationary compressors?

That’s ISO specification #5388:1981 and it has to do with both safety rules and codes of practice for their use.

If your organization needs the actual standard, you can obtain them here in a downloadable .pdf file, or by ordering the printed copy.

If you would like information about air compressors, and using air compressors, here’s the spot.

What’s better, a 1 gallon or 5 gallon tank on your compressor?

Or, a small compressed air tank versus a big one?

It seems as though a lot of folks confuse the discharge flow rate of a particular compressor pump, and the size of the compressor tank. That may be because the retailers of compressors suggest that a larger tank offers a somehow more powerful compressor. Check the fine print!

You can put a really small compressor pump on a very large tank, or the reverse. You want to know what the discharge pressure of the compressor pump is, at the pressure your application requires. That’s how you size the compressor.

The purpose of the tank or receiver is to provide a ready supply of compressed air for an application. If that compressed air using application consumes less compressed air than is in the tank before the tank pressure reaches the compressor cut in point, then the application will run without the compressor head (or pump) from turning on at all.

When the compressor pump works, it runs until the pressure in the tank reaches the cut out point, usually somewhere between 100 PSI and 150 PSI for most compressors. The compressor won’t turn on again until the pressure in the tank drops to the cut in point, perhaps 100 PSI, sometimes as low as 60 PSI. It depends on the type and purpose of the compressor.

The larger the tank you have, the longer the compressor will run until it fills up that tank to the cut out pressure. The larger the tank you have, the more air you have available to use before the pressure in the tank, through using the air, falls to the point that tells the compressor to turn back on.

So, what’s better. A small tank or a large one? It really depends on what you are using the air for. As a rule of thumb, if you can get a larger tank rather than a smaller one for close to the same money, your default option is to the larger tank, in my opinion.

Want some more opinions about compressed air usage? Check here.

Compressor recall….

In cooperation with CSA International, Campbell Hausfeld , of Harrison, Ohio announces the voluntary recall in Canada of approximately 135,000 Campbell Hausfeld and Husky brand air compressors.

It seems that the shroud covering the motor on some units may actually catch fire.

There have been 11 fires reported on these specific units, a very small part of the broad Campbell Hausfeld compressor range. Here’s more information.