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 Junction 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 valves look similar to the valves you find under a sink. They allow you to shut off the flow of the air and water for servicing, as well as a standard connection to the pipes.

• Master On/Off Valves: You will find one master on/off valve (master block) on each of the air and the water main lines. These allow the air and water to flow when the delivery unit is on and stops the flow when 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). They connect 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: For controlling air and water pressure going to the delivery unit. These air or water regulators will have a pressure adjustment, should you need to adjust the levels. Normally this adjustment valve screws in (clockwise) to increase the pressure and out (counter-clockwise) to decrease the pressure. When adjusting the pressure, make certain to have an “active flow.” Hold 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) 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 On/Off Valves

This common master valve has a regulator built in (our #05-54). Locate the filter inside of the valve. The nipple fitting unscrews to expose the filter element.

PHOTO: 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. Access the filter by unscrewing the brass knob on top and then lifting the housing off. This type is often used in an A-dec style of junction box. The brass fitting to the right in the photo helps to attach this valve to a manual shut-off.

Master Valve Filters

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

Take a minute to find and get to know the types of filters in your utility center. They should be checked at least quarterly to be sure your units stay clean and working well. Replacing the filters annually assures proper functions.

NOTE: Always make certain to shut off the air and water at the manual shut-offs, before checking your filters. You also want to exhaust the line pressure by depressing and 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. These valves also provide the necessary fittings to connect to your main air and water lines. They 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 need regular service. If you notice a drop off in air or water pressure to your unit, check for clogged filters restricting flow to your unit. Simply replace the element.

How to Test for Clogged Filters:

1. 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.
2. 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.

Your utility center provides important functions to your delivery system, so getting to know its components help with simple and easy repairs in the future. Replacing their filters on your own saves you time and costly repairs that you can do yourself. Read more about some of the filters in your junction box in Practice Tips #60.