Sluggish and cold…

If you’re a Do It Yourselfer with compressed air, and you, like me, live in the frigid climes, where do you keep your air compressor?

In the garage, like me?

You know how sluggish the truck is when you go to start it after it’s been sitting outside all night freezing. (It’s not in the garage, ’cause that’s where your tools are!). You turn the key, and get that characteristic groan as the starter motor tries to turn over a flywheel that’s mired in thick, frigid oil.

A little later that day you decide that you need to do a little work with an air tool, run your compressor extension cord to an outlet, and the relatively small electric motor on the compressor tries to start moving the compressor piston(s) to compress air. The oil inside the compressor is frozen thick as molasses, and it’s a real hard grind to get going.

Yup, you will burn out a compressor motor if it can’t overcome the frozen head and start moving or, at the very least, you’ll likely pop a breaker.

Take your compressor into a warm place for an hour or two before you try to use it in the winter. You’ll reduce your maintenance woes if you do. If you do “fry” your compressor, you can get another one here. And if you’re interested in more information about compressed air in general, here’s the spot.

What weighs more….?

What weighs more; 500 lbs. of lead, or 500 lbs. of feathers? It’s not a trick question, and because lead is perceived as heavier than feathers, often the answer will be…” the lead”. Of course, 500 lbs. of anything weighs exactly the same as 500 lbs. of anything else. So, what’s my point?

Let’s change the question. What generates more force: 100 PSI from a 200 horsepower compressor, or 100 PSI from the $199.00 do it yourself home compressor? Answer: 100 PSI is 100 PSI, and regardless of the size of the compressor, it’s the same force.

The difference between the massive 200 HP unit and the home compressor is only the speed with which that compressor can deliver that 100 PSI.

The home unit will have 100 PSI available for only a couple of seconds using an air drill, and then the little compressor will kick in, and take quite a bit of time to come back up to full pressure. You stop using the air drill and wait.

The same air drill plumbed from a 200 HP compressor will run much, much longer before that big unit has to kick back in to bring the mains back up to pressure.

My point is, if you aren’t in a hurry, or trying to do so big a job that you might actually wear out the little compressor, for most of us home DIY types a little low-cost compressor will do just fine in generating equal force to the industrial compressor; just taking a lot longer to regenerate it’s pressure.

This summer past we air nailed shingles on a car port roof with my little unit. Nice thing about that little guy too, I could drag it right up onto the roof with me. Nope, I couldn’t nail continuously. But then, it was mighty hot, and the beer was nice and cold, so I had to break every now and again!

Once you get yourself a home compressor, you’ll wonder how you ever did without it.

Here’s a new site offering only compressed air equipment, or click here to learn more about air compressors in general.

About blowing out underground sprinkler lines…

Folks in the south don’t have to worry about this much, but folks in the north have to deal with sub-zero temperatures freezing sprinkler lines. Here’s a question from a reader about dealing with that very thing.

The question:

I have a underground irrigation system and every fall I clear the lines using an air compressor. How do I know the pressure I using is clearing the lines enough to prevent trapped water from freezing?

My lines are 3/4 inch diameter and my longest runs are in excess of 180 feet and the short runs are about twenty.

I have been using a 25 gallon air compressor at 90-125 psi.

What’s your recommendation?

An Answer:

In blowing out sprinkler lines, usually it’s the volume of air and not the pressure that does the trick.

If you’re using 90-125 PSI air, and it works, that’s OK. I’d be a bit concerned about the sprinkler pipe’s ability to handle that pressure?

If you’re blowing air into the sprinkler lines with a 25 HP compressor, you’re generating lots of volume for the application, and I might dial the pressure down to 30-50 PSI just to go easier on the sprinkler lines.

While I’m not a physics major, it seems to me that damage to a sprinkler pipe occurs when that pipe is full of water and then the water freezes. Water expands as it freezes, and if the there’s no place for the forming ice to go, it’s powerful enough to rupture the sprinkler pipe.

If you’re blasting air into the sprinkler lines at the highest point in the sprinkler line, I would think that as long as there’s nothing but mist coming out the other end – after all the free water that had been filling the pipe had been blown down to and out of the outlet – then any small amount of water in the lines shouldn’t present a freezing hazard.

Again, I’m not a sprinkler guy, these are my thoughts.

A reader asks…”Can someone explain the differences between using an aftercooler with filters vs using a afercooler and dryer with filters?”

Bill responded:

Air compressors always generate warm or even very hot, moisture laden, compressed air.

If this hot, wet, compressed air is passed through an after cooler, the compressed air temperature falls and the compressed air can now “carry” less moisture. Water condenses, and the air naturally starts to become dryer as it passes through the after cooler. The same phenomenon can be experienced if the compressed air receiver is big enough to allow the compressed air to sit long enough to cool. It will de-water this way too, though an after cooler will cool the air much more quickly.

A general purpose compressed air filter will be installed downstream from the after cooler and it will strip much of the free water (actual liquid) from the air stream, furthering the work the after cooler has done.

At this point, and depending on how dry the compressed air has to be for your use (remember, the dryer it is the higher the cost to make it so) sometimes the compressed air is then passed through an air dryer.

Dryers work better with cooler compressed air, so it makes sense then, if your compressor is working hard and pumping really hot air into the mains, that this air gets passed through an after cooler and a compressed air filter before it gets to the dryer.

In order to get the compressed air dry enough for your application, you will place drying equipment between your application and the wet compressed air source, the compressor. Consider your compressed air wetness-treatment as a line from wettest to driest. At the “wettest” end you have the compressor, and the driest end the application that is using the air.

Working from the compressor to your application, you will commonly see after cooler(s), general purpose filters, refrigerant or desiccant air driers, more general purpose filters, point of use (often deliquescent) air dryers, more air filters and so on.

You keep treating your compressed air with the various types of air drying equipment available until it reaches your desired point dryness for your use.

That’s why some industrial plants have tons of “air-treatment” equipment, and others have less.

Hope this helps.

Cheers,

Bill

Publisher: www.about-air-compressors.com