An air compressor is the central power source and your major investment. Air compressors are available in horsepowers of 3/4 to 5, or even larger, with a variety of tank sizes up to 80 gallons. The capacity and the frequency and duration of use will determine the horsepower and tank size you’ll need for your own projects. A 2hp or smaller will be adequate for most tanks around the house. Typically these size units will have tanks from 7 1/2 to 20 gallons. Choose an air compressor for quality and protective features. Certification by ASME-the American Society of Mechanical Engineers-is the only guarantee of quality in workmanship and materials, and is a main measure of quality. The ASME label will appear on the tank. All compressors do not have ASME certification. Only ASME certified compressors can be sold in some states.

Other features that will be found in a quality compressor include:

An ASME certified safety relief valve which will allow air to escape automatically if pressure in the tank should ever exceed the maximum. This valve will have a pull ring attached to it to allow you to check the valve to make certain the valve is not clogged or corroded.

An oil level sight glass, a tank pressure gauge and, of course, a pressure regulator and gauge are important, as each tool and job has a specific pressure requirement. The tank maintains air at maximum pressure from 100 to 125 pounds of pressure per square inch. PSI is the force of the pressurized air delivered to the tool. Projects and tools have both pressure and volume requirements. Volume is measured in cubic feet per minute (CFM) or standard cubic feet per minute (SCFM). When selecting and using a compressor, it is the relationship of CFM (volume of air) and PSI (force or pressure of air) that is important.
A manual thermal overload button is important in case of overloads or if the motor overheats. If the motor overheats, it automatically shuts off. This protective control button must be pushed for the compressor to run once the motor has cooled down, preventing a sudden and unexpected restart. The best air intake filtration system will be enclosed and mounted on the side of the compressor. This does more to protect the filtering foam, inside the housing, keeping the compressor cleaner, longer.

A belt guard is indispensable protection and the compressor should never be turned on without the guard in place. A hose rack is desirable for convenience and for protecting the air hose when not in use.

One other feature, most desirable to the do it yourselfer, is a toll free number to call should a question or problem arise.

There are five basic steps in the operation of an air compressor.

1. Check the oil level to make sure the compressor is properly lubricated.
2. Plug the unit into the correct grounded, 3-pronged outlet. Turn the pressure switch on and close the tank drain valve.
3. Adjust the pressure for the tool you will be using and the job you will be doing. Never exceed recommended pressure for the tool or the job.
4. When finished, shut off the motor, unplug the unit, and turn off the regulator valve. Then bleed the air out of the hose, remove the tool and open the regulator to bleed the air in the tank. If you have a quick connect, you must either remove the hose to bleed off the air from the tank or bleed the air through the drain cocks.
5. After storing the hose, open the drain cock to release any accumulated moisture. Leave it open until the next time the compressor is used.

Attachments

Now let’s talk about the available tool attachments. If kept properly cleaned and lubricated, air tools are virtually indestructible. With few actual moving parts, maintenance is minimal. They run cool, since their power source is the compressor.
Perhaps two of the most obvious and useful tools are an inflation kit and quick connect couplers. The quick connect couplers make it fast and simple to change tools. The inflation kit attachments allow you to inflate everything from beach balls to automobile tires.

Blo-gun. This attachment is great for blasting away dirt, grease, and dust from hard-to-reach areas. Never point the gun at the eyes or other parts of the body.

Nail gun. Always be sure the gun is flat against the surface being nailed and know what is on the other side, so you won’t cause damage or injury with the high pressure of the gun.

Air stapler. Again, be sure the stapler is flat against the surface being stapled. Larger staplers are available for attaching roofing shingles and so forth.

Air sander. The dual-action air sander should always be touching the surface when it is turned on. This type sander is frequently used in automotive work but many other uses around the house, such as rust removal or paint preparation, make it a handy tool to have.

Spray gun. This speeds up paint application and gives a smooth finish. There are a variety of spray gun designs on the market for various types of painting. Many times you can reduce the time required to do a job by 50% or more.

Sandblaster. This works well for removing rust and old paint and for preparing surfaces for painting. This same equipment can be adapted for use with soap and water for pressure cleaning such as degreasing auto engines and lawn and garden equipment.

Caulking gun. This tool takes the toil out of caulking, by giving a fast, uniform bead. Uniform and consistent pressure makes for a stronger bead. This tool can be used for any tube material such as adhesive or grease.

Air ratchet wrench. This is great for tightening bolts, whether building a deck, working on an automobile engine or installing a muffler.

Air hammer/chisel. The masters jobs from masonry to tailpipe removal. It must be up against the surface when started.

Air drill. An air drill makes drilling into any surface an effortless task.

Impact wrench. This is used in automotive and assembly work.

Most air tools are available at hardware stores and home centers. Specialty air tools can be rented. Instructions for each tool attachment are included with the purchase or rental. Read these instructions carefully before attempting to use the tool.

source: http://www.doityourself.com

Instructions

1. Check to make sure that the cord is plugged into the outlet firmly and that the power switch is on. If power is not restored, locate the “Reset” button located on the side of the compressor motor, typically near where the power cord is attached. Look for a round black or red button. Depress the button to reset the circuit breaker. If power is not restored, continue to the next step
2. Trace the cord to ensure that all connections are snug. Plug any cords in that are loose.
3. Locate the circuit breaker box and check for circuit breakers that have tripped. Look for a small red square near the breaker to indicate a breaker that has tripped. Flip tripped breakers to the full “Off” position then back to “On.” If power is not restored, continue to the next step.
4. Test the outlet by plugging in a small radio or lamp. If the outlet works, remove any extension cords and plug the compressor cord directly into the outlet. Test the compressor again. If power is not restored, take the compressor for professional servicing.

Building Pressure

1. Unplug hoses and tools. Turn the compressor on and allow it to charge. Spray soapy water around the fittings of the compressor and check for bubbling to indicate air leaks. Release the pressure from the tank by pulling the air release valve. Look for a small plastic/metal valve near the air outlet with a pull ring attached.
2. Remove fittings that have actively bubbling soapy water surrounding them with a wrench. Turn the fittings counterclockwise to remove them. Wrap teflon plumber’s tape around the threads of the fittings.
3. Thread the fittings back into the compressor and tighten with the wrench. Test again, charging the compressor and spraying with soapy water. Replace fittings that still leak.
4. Charge the compressor. Locate the bleed valve on the bottom of the air tank. Grip the valve with locking pliers and turn it counterclockwise to open it. Allow the air to blow the condensation from the tank until the air escaping is dry. Tighten the valve by turning clockwise.

Adjusting Air Flow

1. Remove the plastic shroud from the top of the compressor by removing the screws with a screwdriver. Lift the cover off to expose the pressure limiter screws; there will be two screws. The lower control screw, closest to you, controls when the compressor comes on. The upper screw controls when the compressor goes off.
2. Start the compressor and make a note of the pressure setting when the compressor kicks off. Adjust pressure up or down with the upper control screw. Tighten the screw clockwise to raise the pressure, or counterclockwise to lower it.
3. Pull the pressure release valve and make a note of the pressure when the compressor comes on. Adjust the lower control screw to raise or lower the setting. Replace the cover and replace and tighten the screws with a screwdriver.

source: http://www.ehow.com/how_7872768_repair-air-compressors.html

Axial compressors are rotating, airfoil-based compressors in which the working fluid principally flows parallel to the axis of rotation. This is in contrast with other rotating compressors such as centrifugal, axi-centrifugal and mixed-flow compressors where the air may enter axially but will have a significant radial component on exitAxial flow compressors produce a continuous flow of compressed gas, and have the benefits of high efficiencies and large mass flow capacity, particularly in relation to their cross-section. They do, however, require several rows of airfoils to achieve large pressure rises making them complex and expensive relative to other designs

Axial compressors consist of rotating and stationary components. A shaft drives a central drum, retained by bearings, which has a number of annular airfoil rows attached. These rotate between a similar number of stationary airfoil rows attached to a stationary tubular casing. The rows alternate between the rotating airfoils (rotors) and stationary airfoils (stators), with the rotors imparting energy into the fluid, and the stators converting the increased rotational kinetic energy into static pressure through diffusion. A pair of rotating and stationary airfoils is called a stage. The cross-sectional area between rotor drum and casing is reduced in the flow direction to maintain axial velocity as the fluid is compressed.

Axial compressors are widely used in gas turbines, such as jet engines, high speed ship engines, and small scale power stations. They are also used in industrial applications such as large volume air separation plants, blast furnace air, fluid catalytic cracking air, and propane dehydrogenation. Axial compressors, known as superchargers, have also been used to boost the power of automotive reciprocating engines by compressing the intake air, though these are very rare. Continue reading

An air compressor is a device that converts power (usually from an electric or diesel or gasoline engine) into kinetic energy by pressurizing and compressing air, which is then released in quick bursts. There are numerous methods of air compression, divided into either positive-displacement or negative-displacement types.^[

Positive-displacement air compressors work by forcing air into a chamber whose volume is reduced to effect the compression. Piston-type air compressors use this principle by pumping air into an air chamber through the use of the constant motion of pistons. They use unidirectional valves to guide air into a chamber, where the air is compressed. Rotary screw compressors also use positive-displacement compression by matching two helical screws that, when turned, guide air into a chamber, the volume of which is reduced as the screws turn. Vane compressors use a slotted rotor with varied blade placement to guide air into a chamber and compress the volume.

Negative-displacement air compressors include centrifugal compressors. These devices use centrifugal force generated by a spinning impeller to accelerate and then decelerate captured air, which pressurizes it. Continue reading