The obvious is no water required in most dry vac systems. What is often overlooked is the need for exhaust and piping. With a wet system the air goes down the drain with the exhausted air and debris.

With dry vac you require a good air-water separator to allow the liquids to drop out of the air stream so they do not go through the pump. There are many different types that we can look at another time.

No, no, absolutely no. I bought two things recently that were rated with horsepower as the power differentiating value. My leaf blower has a sticker that says 25 peak Hp. I carry it in one hand or on my back. A 25 Hp motor of any kind is heavy, something’s not right. My shop vac is awesome. It too has a sticker claiming 12.5 peak Hp. I plug it in to the same outlet I use to plug in my shaver. I do not have a fuse in my panel strong enough to run a 12.5 Hp motor. Something is wrong. The above tools are using Hp to measure something but it’s not the power of the electric motor.

In dental dry suction the vacuum pumps are all very different. Some are high flow, some with oil some completely dry. As discussed in another note it’s really the matching of volume to vacuum that creates the velocity to make things happen.

This question is the last to be asked by someone thinking about switching from dental wet suction to a dry suction system. The answer should be “Relax, it will never happen, we have this safety and that switch all to protect your system”. But it does happen. Safety switches and floats can be switched off, unplugged or slow to respond letting water into a dry pump.

The result is normally not good. An oil lubricated pump (I like saying that, but how can it be dry, oil is wet!) will mix the liquid with the oil and the pump will fail due to lack of lubrication. Good news is it takes time to fail and if you catch it quickly and change the oil and everything will be OK. You will notice the pump cannot reach its ‘’Hg maximum because the oil water mixture no longer acts as a good seal inside the pump.

In dental dry vac pumps heat has always been one of the post mortem causes of failure. If they operate in a closet or box the heat has nowhere to go which causes the pump to continue to heat up.

In the case of turbine or regenerative types the only means of cooling the pump is from the motor fan (usually plastic and only designed to cool the external motor housing) and by the air running through the pump. When not enough flow occurs in a high flow pump (due to the small holes in the dental suction tools) the pump’s safety valve opens to help cool the pump from air from the hot box or room. The result is normally a bearing failure caused by the grease drying out and no longer lubricating. The oil lubricated dry pump (sort of still a wet pump) handles the heat much better from inside the pump. As long as you keep the pump in a ventilated area and change the oil frequently it handles the heat quite well.