How to Fill a Portable Air Tank

by G.K. Bayne

Portable air tanks typically range in capacity from 5 gallons to 8 gallons. The light weight of the small cylindrical tank makes it ideal for adding air to a low-pressure automobile tire. The air tank's small capacity and pressure generally will not fill a completely flat tire. The portable air tank is also useful for inflating small air mattresses and has enough capacity to fill up four or five basketballs. Generally these portable air tanks are filled with a regular air compressor.

Set the portable air tank on the ground in close proximity to the air compressor. Use the pressure tire gauge to check for any remaining air in the tank if the air tank does not contain an onboard air gauge. Observe the safety label on the side of the portable air tank. The maximum pressure allowed for most portable air tanks is not greater than 120 PSI (pounds per square inch).

Start the air compressor. Allow the pressure of the air compressor to reach maximum, generally 120 PSI. Place the filling valve from the compressor to the filling valve on the air tank.

Fill the air tank to approximately 50 PSI. Open the lower water drain valve on the air tank and release any water condensate from the tank. Close the drain valve once all signs of water have ceased flowing from the valve.

Continue to fill the air tank from the compressor. Stop filling once the tank has reached the manufacturer's displayed tank pressure maximum.


  • check Always drain the condensate water from the air tank. Water left inside the tank will take up volume and cause steel tanks to rust. The rust will eventually create a hole in the bottom of the air tank and a leak.


  • close Never exceed the manufacturer's pressure rating on the portable air tank. This can cause the small vessel to rupture and pose a possible hazard to personal and equipment.
  • close High-pressure compressed air tanks must be filled by certified technicians. These tanks are used for portable air tools and can exceed internal pressures of 1000 PSI.

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