How to Fill Portable Air Compressors

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The two gauges on an air compressor show the pressure in the air tank and the amount of air the regulator is releasing.
Image Credit: dies-irae/iStock/GettyImages

Air compressors are used to operate air-powered tools like nail guns and staplers. With special add-ons, you can also use them to inflate rafts or air mattresses, or blow away debris from small spaces. Compressors are also used to operate air-powered paint sprayers. Portable air compressors should be fully depressurized before you start using them to ensure correct pressure for the current task.


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Step 1

Put on closed-toe shoes and safety glasses whenever working with an air compressor or power tools.

Step 2

Check the oil level in the air compressor, and add oil if needed.


Step 3

Make sure the power switch on the compressor is set to "Off." Confirm the outlet pressure is at zero by turning the pressure regulator knob counterclockwise all the way. This will remove any air pressure at the outlet.

Step 4

Attach one end of an air hose to your compressor's regulator valve and the other to your tool.


Step 5

Connect the compressor to a wall outlet and turn the power switch on the compressor to the "Auto" setting.


Never plug an air compressor into an extension cord. Instead, use a longer air hose or add a second hose, if necessary.

Step 6

Stand by and allow the machine to reach maximum pressure. The compressor will charge; the tank will fill with air and gain pressure. You can monitor the pressure on the tank pressure gauge.


Step 7

Set the regulator to the pressure recommended by your tool manufacturer. They are all different, so check. Sometimes it will be labeled on the tool. Just rotate the pressure regulator knob and monitor the outlet pressure gauge.


As you work, the compressor will cycle on and off to maintain the pressure you have set. Just because the compressor’s motor is silent, it doesn’t mean the tank isn’t full of air or at the proper pressure.

Step 8

When you are done, turn the air compressor off; unplug it, and disconnect the air hose. Drain the pressure from the tank using the pressure relief valve.