Practice Tips #23: Getting to Know Your Utility Center

Getting to Know Your Utility Center

Your utility center or junction box assembly (j-box) houses the valves and regulators that distribute your air and water sources to your delivery unit.  The j-box may also house  the drains for cuspidor and/or central vacuum system as well as a duplex electrical supply to power your fiber optic systems (or other systems that require electricity).  In other words, the contents of your j-box are probably some of the most important in your operatory.  Let us look in the “box”.

What are the major components in the j-box?

    • Manual Shut-Off Valves: Normally, the manual shut-off valves attach via a 1/2” FPT (female pipe thread) to the pipes that carry the air and water supply from their sources to your operatory.  These shut-off valves look similar to the valves you would find under a sink.  Their purpose is to allow you to shut off the flow of the air and water for servicing and to provide a standard connection to the pipes.

Manual shut-off valve (#49-90)

  • Master On/Off Valves: You will find one master on/off valve (master block) on each of the air and the water main lines.  The master on/offs allow the air and water to flow when the delivery unit is on and stops the flow when the unit is off.  A “relieving” or exhausting master toggle (normally in the delivery unit head) activates these valves with an air signal (see our issue on toggles). The master valves are normally connected directly to the manual shut-off valves with a 3/8” brass compression fitting.  If a self-contained water system (bottle) is used as the only source of water to the unit, you may not have a master valve on the waterline (or even have a water line plumbed into the operatory).  In such circumstances, it is normal to have only one master valve – on the airline.
  • Regulators and Gauges: The regulators precisely control the pressure of the air and water supply going to the delivery unit.  There will be one regulator for air and one for water.  These regulators will have a pressure adjustment should you need to adjust the air or water pressure.  Normally this adjustment valve is screwed in (clockwise) to increase the pressure and out (counter-clockwise) to decrease the pressure.  Whenever adjusting the pressure, make certain to have an “active flow”- most easily accomplished by holding down the air or water button on your syringe while adjusting the corresponding regulator. The gauges display the pressure of air or water in pounds per square inch (PSI) being sent to the unit.  For most units, proper supply pressure is 80 PSI for air – 40 PSI for water.
  • Filters: The filters are usually incorporated into your master valves but can be incorporated into the regulators or exist as separate inline entities.  The main line filters are some of the most important items in the junction box but also the most commonly overlooked.  Generally, the filters will be in round housings.  The filters stop “particulates” from entering your unit.

Master valve with regulator built in (#05-54)

This is a common master valve with the regulator built in (our #05-54). As indicated, the filter is under the round housing at the end (this is also where this valve attaches to the manual shut-off). The knurled housing simply unscrews to expose the filter element.

Master valve with clear filter (#05-558)

This is another common master valve. The cylindrical housing shown on top in the photo contains the filter. This housing may be clear, white, chrome, or other colors as well. The filter is accessed by unscrewing the brass knob on top and then lifting the housing off. This is the type often used in A-dec junction boxes. The brass fitting to the right in the photo is for attaching this valve to a manual shut-off.

There are many other configurations possible, but your master on/off valves will normally be connected directly to the manual shut-offs, the regulators will have a gauge associated with them, and the filters will be within a round housing which may be incorporated into another valve.

Take a minute to find the filters in your junction boxes. They should be checked at least quarterly to be sure your units stay clean and working well. Replacing the filters annually will assure they work well.

NOTE: Always make certain to shut off the air and water at the manual shut-offs before checking your filters. You will also want to exhaust the line pressure by depressing & holding both buttons of your air/water syringe until all flow stops.

Why are these valves and regulators important?

Today’s dental units require a regulated source of air and water to run correctly.  You may experience problems if your air and water are not set at the correct operating pressures. Premature turbine failure, erratic handpiece performance, leaking of air or water, and other problems can all result from unregulated or improperly regulated air and water. The master valves shut off the flow of air and water to the unit when not in use to minimize wear and tear and reduce the risk of damage should a unit leak after hours. The master valves also provide the necessary fittings to connect to your main air and water lines and will have multiple outlets to direct the air and water to the various valves within your unit.

Do I have to service these valves?

These valves should last a long time before they need replacing.  However, the filters that are usually incorporated into them will need regular service.  If you notice a drop off in air or water pressure to your unit, it is possible the filters have become clogged and are restricting flow to your unit.  Simply replace the element.

To test this, grab your air/water syringe.  Press the air button while looking at the gauges in your junction box (not on your unit).  If the air pressure drops off by 15 pounds, you should replace the air filter.  Do the same thing for the water.  Press the water button while looking at the gauge in the junction box.  If water pressure drops off by 10 pounds, replace the water filter.


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