Fifty percent of the time, when having problems with your delivery unit, it involves air and water pressure. Check this first if you are not getting air or water to your handpieces. An important thing to take note of is the role of the master on/off relieving toggle.
Signs of a Bad Toggle:
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Inability to Turn On or Off:
If you find that you cannot toggle the air or water flow on or off, it indicates a mechanical issue. -
Rigid Toggle Movement:
The toggle switch should move smoothly between positions (on/off) with a definite position in place. If you notice it feels loose it suggests a problem inside of the switch and may not be engaging the inner mechanisms. -
Poor Flow Control:
Sometimes, the master on/off toggle switch might allow intermittent or inconsistent control over the air or water flow. Check for a loose connection. If you notice that air or water continues to flow in the "off" position, it indicates it can’t control the flow effectively.
Diagnose the Problem
When you flip the master relieving toggle to the off position, do you hear a slight hiss of air relieving itself from the line? If you do not hear the hiss, then an air signal was never sent to the master valves in your junction box. This means air can’t open the diaphragms in the master valves. It does not allow the air and water to flow freely.
Your master toggle may very well be the problem. If you take the line off from the back of the toggle, there should be air flow as long as your compressor is on. If there is air flow, then your master on/off toggle has gone bad. You have air going to the toggle, but the "on" position doesn't allow the air signal to flow.
Temporarily Fix the Problem
For now, put the two lines together with a double ended barb (#14-11). This allows your delivery unit to function. However, it will always stay on, unless you pull the two lines apart at night. This will get you through until a new master toggle can be sent to you.
Once you turn your compressor on in the morning, air goes directly to your master toggle from an open port on your master on/off air valve in your junction box. This line of air stops at the toggle and waits for you to turn your unit on. When you flip the toggle to the on position, a second line of air goes back down to your junction box. At that point, the line splits and an air signal is sent to each master valve (air and water), opens the diaphragms and your unit is ready for use.
Repair the Problem
What do you need to repair and replace on your delivery unit? The toggle you need is our part #05-02. This is a relieving toggle, which means that when it is in the off position, it relieves the air still in the line. If it did not relieve, then the masters may not close because of the pressure trapped in your line. Once it relieves, you know that your masters (such as #05-54 shown below or #05-558) are shut down at the hard plumb.
Pressure settings for your valves are 80 psi for air and 40 psi for water. For more on the importance of these settings and how to adjust them, see some of our previous issues of Practice Tips (#3, #23, #69, #73).
By addressing issues with the on/off relieving toggle promptly, you can maintain efficient operation of your dental delivery unit and ensure optimal patient care during procedures.
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