This month we share some tricks and tips used by our technicians when dealing with the various types of fittings. These are tricks we have learned over the years to make the connections easier and more secure. For more information on the types of fittings check out our Practice Tips Archives- Issue #5: A Brief Introduction to Dental Fittings.
When using barb fittings a number of additional steps can be helpful.
Rather than pushing the sleeve all the way over the tubing, pull the tubing through the sleeve. Once you’ve got the tubing pushed through a little bit, just grab the tubing with a pliers and pull it through as far as you need. You can get much more leverage this way.
When connecting multi-line tubing (such as foot control or syringe tubing) use a sharp knife or dental tubing splitter to cut the area between the lines and then pull them apart. Once the lines are separated, also trim the excess material from between the lines with a knife. The excess material can make it extremely difficult to get the tubing through your sleeve clamps.
Dipping the tubing for a few seconds in hot water will soften the tubing making it easier to slide over the barb. One of our techs will occasionally use coffee, not only does the heat soften the tubing, but the oil will act as a lubricant as well. You can also lubricate the barb with liquid soap to slide the tubing on.
Always make certain to slip the sleeve clamp over the tubing before sliding the tubing onto the barb. If installing onto a syringe, also make certain to slide the syringe handle over the tubing first.
Another tip when installing syringe tubing- when initially installing the sleeve clamps onto the tubing, slide the sleeve clamp on the water line farther down the tubing than the sleeve on the air line. This helps one keep track of which line is which so you don’t connect backwards and then need to re-attach.
Once you have your sleeve clamps on the tubing, slide the tubing onto the barb but only about half way. Once you push the sleeve clamp up, it will grab the tubing and push it the rest of the way. If the tubing is already fully seated, when the sleeve is pushed up the tubing can “bunch” making it very difficult to fully seat the sleeve.
Another common multi-line item is the foot control. For foot controls with 3 or more lines, the smaller lines will often need to attach to secondary valves under the “dome” of the foot control or on the sides or back of the block so these lines will need to be longer than the larger main air lines. In such cases, connect the smaller lines first and then trim the larger lines shorter to avoid kinking or bunching the tubing under the dome.
For some items with barbs grouped too closely together to use sleeve clamps (e.g. handpiece blocks), you can use tie straps to hold the tubing in place. When using tie straps, be sure to fully seat the tubing and use a pair of pliers to cinch the strap as tightly as possible.
Sleeve clamps will be tapered at one end and cut square at the other. The tapered end should be placed toward the barb when installing tubing onto a metal barb (you’ll need more “give’) and the square end should be placed toward the barb when attaching to plastic barbs (as the barb will “give”)- see image below.
When attaching tubing with a compression fitting, one or two wraps of Teflon tape over the smooth internal fitting will help to provide a good seal once the tubing is seated.
As with barbs, be sure to slide the nut and compression sleeve over the tubing before you attach the tubing to the fitting.
Once you screw down the nut, be careful not to over-tighten as you can crack the plastic sleeve. The nut should be securely and firmly tightened, but do not use a tremendous amount of force.
If replacing tubing in an old fitting, sometimes a new nut and sleeve will be required as the plastic sleeves can wear or distort over time.
Regardless of fitting type, always use the appropriate tools. A sleeve tool is specially designed to push the sleeve clamps into place and works much better and more easily than trying with just your bare hands or a slip-joint pliers.
Likewise, an open-end wrench should always be used for the nuts of a compression fitting, and never a pliers. Pliers can strip and mar a nut rendering it useless and simply do not give as much leverage as a proper wrench.
A good sharp knife is invaluable in trimming excess. For smaller supply lines (3/8” o.d. or less) a diagonal wire cutter works very well to cut the line. A strong scissors will also work (such as our utility shears) but for the smallest lines, a wire cutter usually works better and will get into tight spaces more easily.
If re-attaching an old line, trim the tubing back a few inches to get a fresh end. With age the tubing can stretch or distort where it had been attached and may not stay secured if re-attached.
If purchasing new tubing, always measure your old tubing first. It’s usually a good idea to add an extra foot or so as well to provide a margin for error. It’s always easier to trim the tubing a little than to try to stretch it if you’re a little short.