Compressed Air Basics: Vibration Isolation

A Whole Lotta Shakin' Goin' On

Your compressor shakes.  The machinery in your shop shakes.  When air goes through a pipe, it shakes the pipe.  The technical term for this shaking is vibration.  There's vibration in nearly everything you use. 

Sometimes this vibration can cause machinery to fail and cause pipe fittings and welds to leak.

Actually, I should rephrase that....It will cause machinery to fail and cause pipe fittings and welds to leak, if nothing is done about it.  That's why every compressor must be isolated from vibration.  There are two places that are a concern for every air compressor.

FLEX HOSE AFTER THE COMPRESSOR

Every compressor manufacturer says that you need to put a vibration isolator or flex hose between the compressor and the pipe system.  I'd say about half of our customers know this already, before we mention it to them.  However, it's important that we get the word out to everybody else.

The reason for this is that your compressor vibrates, the machinery that uses the air vibrates, and when air goes down the pipe it vibrates the pipe.  The vibrations from different sources have different harmonics - they vibrate at different frequencies and different amplitudes.  When you don't isolate the vibrations of different harmonics, it wears out the components much more quickly.

Not only that, but the compressor was built and tested to withstand its own vibration.  It was not built to withstand different harmonics.  There's no possible way for the manufacturer to test all the conditions that a compressor can see - there's an infinite amount of possibilities. 

You won't see it immediately.  This is a long term effect that we're discussing.  Usually it takes a couple of years for the lack of vibration isolation to cause a problem.  The problems on the compressor usually exhibits itself as a leaky oil cooler or air cooler.  For the pipe it will break welds or cause leaks.

There's a chance it may never cause a problem.  However, putting in a $20-$100 flex hose to prevent thousands of dollars in broken parts seems like a no-brainer to me.   You can just use a rubber hose.  Make sure it meets the pressure, temperature, and flow specifications.  Most of the time we use metal flex hoses.

VIBRO-PADS WHERE THE COMPRESSOR IS MOUNTED

The other place where you have to worry about vibration is where the compressor is mounted.  There should be a rubber pad or foot at the bottom of the compressor.  Sometimes the compressor will come with these already installed; sometimes you'll have to add them yourself.

If you don't do this, the weld where the foot of the tank meets the tank will crack.  Again this could take several years, but why make a tank that should last decades only last a few years?  For $20 worth of parts (we sell vibro-pads for $4.95 each), this can be avoided.
 

Every Kaeser Rotary Screw Compressor comes with mounting feet that vibrationally isolate it from the floor.

 SO LITTLE TO INVEST; SO MUCH TO LOSE

Manufacturers can void your warranty if you don't install the compressor properly, and they would be correct to do so.  If you don't isolate your compressor from vibration, the problems with the compressor would be your fault.  They weren't caused by manufacturing defects; they were caused by a bad installation, which was out of the manufacturer's control.

You can't drive your car into a lake and expect the dealer to fix everything for free because the car is under warranty.  In the same way, you can't install your compressor the wrong way and expect the problems caused by the installation to be covered under warranty.

A flex hose is $20-$100 and vibro-pads are about $20 total.  The amount that we're talking about is nothing compared to price to fix a compressor.  If your compressor doesn't have a flex hose between it and the air system, go fix that now.  If your compressor mounts directly to the floor (or whatever else you mount it to, like a truck bed) without rubber pads, go fix that now.  It's quick and easy and will prevent thousands of dollars in problems.