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Practice Tips #3: Dental Unit Pneumatics

Basic understanding of your equipment will save your practice money

Key Take-away: 80 PSI AIR, 40 PSI WATER

As most of you are aware, the typical dental unit is powered by air (pneumatic). Even the water in the unit is air-activated.

Proper supply pressure is crucial to keeping your units functioning as you need them to. As the water is normally air activated, you will need at least a 2:1 air to water pressure ratio. Normal supply pressures should be 80 psi for the air and 40 psi for the water. This is the main pressure in the junction box, not the pressure at the unit. Check the gauges where the air and water comes into the room (You’ll normally have two master valves in your junction box, one for air, and one for water).

Note— the master valve can only regulate the air pressure down. It is important to have your compressor set high enough (about 100 psi) to get a solid 80 psi in the operatories.

If you’re having trouble locating or reading the gauge in your junction box, there’s a simple little trick you can use to estimate your water pressure. Hit the water button on your air/water syringe and measure about how far the water sprays. For every one foot of water stream, you have approximately ten psi of water pressure. As ideal water pressure is about 40 psi, you’ll normally want about a 3-4 foot stream of water from your syringe.

If your supply pressure is set incorrectly, you must have an active flow to adjust it. Simply hold down the air or water button on your air/water syringe while adjusting your regulators.

Most regulators will be marked with an arrow to indicate how to adjust the pressure. If not marked, generally you need to screw the adjustment knob in (clockwise) to increase the pressure and out (counter-clockwise) to decrease the pressure.

The first step in troubleshooting your unit should be verifying correct supply pressures. Just remember: 80 AIR, 40 WATER.

If you’ve got consistent problems with supply pressure, or if you are unable to maintain pressure, check your filters in the junction box. Clogged filters will impede steady flow of air and/or water and should be changed.

Check your Filters for Optimal Performance

Add checking your filters to your quarterly routine.

Good filtration will help keep your equipment running well and will also maximize your compressor’s life. A coalescing filter should be used in conjunction with a good desiccant dryer on the compressor.