Tag Archives: auto

  • How Air Compressors Work

    The concept behind the air compressor is a simple one and easily understandable to anyone who is into old cars and such. The reason the pump on the top of your compressor looks like a simplified motorcycle engine is because it basically is. The vast majority of compressors, from the tiny 12v tire inflator you stash in your trunk to the big 80 gallon shop unit, basically compress air with an air cooled piston engine. In fact, there are kits to turn air cooled VW bug motors into gas powered air compressors that could be mounted in the bed of a truck; two cylinders power it and two compress the air.

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    When the electric motor kicks in, the piston is drawn down the stroke of the cylinder. A simple spring-loaded one way valve opens allowing clean atmospheric air in, usually sucking thru some kind of air filter to keep out dirt and dust just like your car. The piston then moves up, compressing the air, and a 2nd valve opens to let the now pressurize air into the tank, or out into your tire in the case of a tire inflator or the one outside at the gas station. When a gauge signals that the tank has the correct pressure, the motor stops.

    Because air tools, spray guns and the like only allow the air out thru a restriction, the tank stays pressurized for a while. If an air hose were to break, the air would all come out pretty quick and return to atmospheric pressure in seconds. The CFM rating on a compressor indicates how many cubic feet of air per minute can leak out via the tool you are using before the pump would be unable to keep up with the demand at a given pressure.

    Multi-Stage and Screw Compressors

    There are variations on how air compressors work. There are multi stage reciprocating compressors, and nearly silent rotary screw compressors.

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    Two stage compressors typically have a v-twin looking head on top of the tank. The first cylinder works just like a single stage, but instead of feeding the tank, it feeds the intake on a second smaller cylinder, the second cylinder, then compresses it even more. There are also three piston versions that work the same way, as well as single stage multi-cylinder units for more air flow at lower pressures.

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    Rotary screw compressors work more like a Roots-type supercharger. Two rotors intermesh, forcing air into a smaller space along the length of the rotors, and finally out into the tank. Because of how they work, they produce more of a constant “whir” then the “chuga-chuga” of a reciprocating pump. This makes them popular for applications where noise is an issue. This type of compressor is also generally used in larger industrial application because of its increased efficiency and ability to deliver larger volumes of air at high pressure.

    Care and Maintenance

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    No matter how you compress the air, you have to deal with the physics of thermal dynamics and moisture. Squishing the air makes it hot, it’s an unavoidable by-product of compression, which is why some units have cooling fins on the supply line to the tank, or even a separate intercooler. All air has moisture in it too and compressing it results in condensation, which is why you need to drain the tank occasionally, and use an air dryer in applications like spraying paint. Just like an engine, compressors need to be lubricated, and if you are spraying paint, you need to strip the oil out of the airstream as well as the water. Luckily, most air dryers function this way already.

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  • Eastwood’s ‘Shop Talk’, Episode 36: TC Penick & The Crew of Bay One Customs

    Sit tight & listen to Kevin, joined by TC Penick and the boys from Bay One Customs, taking the time away from saving Kevin’s butt yet again for this week’s episode of Shop Talk.  Click Here To Read Full Post...
  • Eastwood’s ‘Shop Talk’, Episode 35.5: TC Penick - Custom Builder & Owner of Bay One Customs

    On this upcoming episode, we’ll speak with TC Penick of Bay One Customs out of Springfield, Tennessee. TC turned heads at SEMA 2013 with his 1958 Chevy Cameo Concept Truck.   Click Here To Read Full Post...
  • Eastwood’s ‘Shop Talk’, Episode 35: John Bouchard - Master Engine Builder

    Former host of Horsepower TV, John and Kevin are both familiar with being in the spot light. Lately though, John’s work building flawless engines has garnered all the attention.  Click Here To Read Full Post...
  • Eastwood’s ‘Shop Talk’, Episode 34.5: John Bouchard, TV Host and Master Engine Builder

    Sit tight & listen to Kevin as he previews things to come on next week’s episode of Shop Talk, where he talks with John Bouchard.  Click Here To Read Full Post...