Practice Tips #116: All About the Manual Shut-off

Dental delivery systems are all powered by compressed air, some are also connected to municipal water lines. Pipes are plumbed throughout the office to bring air from the compressor and water to the delivery systems. What makes this all work properly are: plumbing fittings.

In order to connect to your plumbing, the easily overlooked manual shut-off valve is usually used. More properly referred to as an “angle stop” and commonly referred to as a “toilet valve” (as they are used to connect the water to your toilet). These valves are simple, versatile, and effective.

The Angle Stop Valve (#49-90)

The manual shut-off serves two purposes. Its first function is to adapt your pipes (usually ½” copper) to the smaller sizes of lines that are used by your delivery system. Second, it allows you to shut the air (or water) to the operatory off, often necessary for maintenance or repair.

To connect to your pipes, the standard manual shut-off has a ½” female pipe thread inlet at the bottom of the valve. This is a threaded female fitting that attaches to a ½” i.d. pipe. It simply screws onto your pipe.

Note: the female pipe thread at the bottom of the valve

The outlet fitting of the manual shut-off is a 3/8” brass compression fitting. If uncertain of the size, one measures the diameter of the fitting. Most master valves have a 3/8” brass compression nipple specifically to attach to the manual shut-off.

Manual Shut-off Valve (#05-558)

As discussed in Practice Tips #5, a compression fitting consists of a nut with a sleeve inside. As the nut is tightened down, the sleeve compresses (hence the name) onto the male fitting to hold it in place. Compression fittings are smooth. One does NOT attach to the threads of the compression fitting, those are for the compression nut and sleeve.

Do not attach anything, other than the compression nut and sleeve, to this thread.

It’s not unusual over time for the compression nut and sleeve to become lost (once used, it’s also not normally possible to remove them from the nipple fitting), so we regularly encounter manual shut-offs without the compression nut and sleeve. If your manual shut-off is missing the nut and sleeve, you’ll need to purchase a new set to attach anything to your valve.

Compression Nut & Sleeve (#49-91)

One often needs to attach to a manual shut-off to add an air powered device (such as a Micro Etcher or lab handpiece) into the lab or sterilization area. A 3/8” compression nipple fitting with a tubing connector is often used to attach to the manual shut-off in your lab and will also attach to a standard ¼” o.d. supply tubing. The manual shut-off has a 3/8” compression outlet, so you must use a 3/8” compression nipple to attach to it. There are a variety of 3/8” compression fittings to allow attaching to different sizes of tubing, pipe thread, or other fittings.

These are a few compression fittings with 3/8" outlets (#13-62 & #13-79).

Manual shut-offs are used in many places throughout your office — under sinks, in the ops, in the lab or sterilization area, and even to connect your toilets. Knowing how to work with these valves will save you both time and money that can be spent elsewhere.