The dental oral vacuum system is one of the most important pieces of equipment in your office. Together with the compressor system, much of what you do depends on this product working properly, so make your choice carefully.  There are many key features to look at that will impact your practice. 

When looking for an oral vacuum system for your dental practice, here are some key points to consider:

  • Performance and technology of the vacuum producer: There are two specifications used to measure the performance of a vacuum producer:
    • Cubic Feet per Minute (CFM) of air flow
    • Inches of Mercury Lift capability (In. Hg)

Both specifications are important and related. The CFM specification indicates the amount of air flow through the vacuum system. The higher the CFM, more vacuum outlets (high volume evacuators and saliva ejectors)  that can be used simultaneously at an acceptable level of vacuum lift (In Hg). The vacuum lift capability is measured in  In. Hg, Most vacuum producers have a gauge that shows the In. HG level.  For general dentists and most specialists, the amount of vacuum lift needs to be in the 5  to 10 In. Hg range. For oral surgeons, the desired amount of lift is usually more than 10 In. Hg.  As more vacuum outlets are opened simultaneously, the amount of vacuum lift will drop, so proper sizing of the vacuum producer is very important.


There are two primary  types of vacuum producers available for dental applications. Since the late 1960’s, water ring (or water injected) vacuum producers had been the standard. These products use city water, injected into the pump housing, to create a tight seal around the impeller. This tight seal helps create a high amount of vacuum lift. The CFM on these products is fairly low however, so as vacuum outlets are opened, the vacuum lift diminishes. Once the number of outlets used exceeds the vacuum producer design specifications, the amount of lift will not be acceptable.  In addition, these vacuums use between a quart and a gallon of city water per minute of use. Water ring vacuums for large dental facilities will have two or more vacuum producers. Since the vacuum is usually turned on all day, there is a lot of water and sewer usage to service these systems.





Since municipalities ( and dentists) have been concerned about wasting water resources, many cities and counties have restricted or banned the use of water ring vacuum systems in dental offices. This is one reason that dry vacuum producers are becoming the standard now. These products use no city water to produce the vacuum. The vacuum lift with all vacuum outlets closed is usually less than the water ring vacuum systems, but they have much higher CFM of air flow through the vacuum system. This means that as vacuum outlets are opened, the In. Hg vacuum lift does not drop significantly.  The motor and impeller system must stay dry, so a air/water separator tank is required. The air and fluids from the treatment room vacuum outlets enter the separator tank, the air component travels to the dry vacuum producer and the water goes to the sewer system. Since the vacuum producer moves only air, the motor does not have to work as hard as the motor in the water injected vacuum, saving electricity. With no water used to produce the vacuum, a reduced volume of water flowing into the sewer system and less electricity usage, the utilities cost to run dry vacuums can be significantly less than needed for water injected systems.

Since dry vacuum vacuum systems move a higher volume of air, the diameter of the main vacuum piping is larger than the piping used for water injected vacuum systems. If your office currently has a water injected vacuum system and you are changing to a dry vacuum,  you may need to replace your main vacuum lines with a larger diameter pipe. Consult with your distributor to confirm what needs to be done to assure that your new vacuum works as designed.

  • Maintenance requirements: Both water injected and dry vacuum systems require some periodic maintenance, but it is minimal. For the water injected vacuum, it might involve only a weekly check and  cleaning or replacement of the vacuum inlet screen. On dry vacuum systems, the air/water separation tank may need to be rinsed from time to time. Ask your distributor about the specific maintenance requirements of the vacuum that you are considering, and discuss who will be doing the maintenance. If your distributor will be doing the maintenance, who will schedule it? Some distributors will set up preventative maintenance services calls automatically so you do not have to worry that the maintenance is being done. Otherwise, you will need to call your distributor at the prescribed maintenance intervals to get the work done. If your dental office team is going to do the maintenance, keep in mind that this may require time away from your patients, which can be costly. One way or another, it is critical that the periodic maintenance be done or you may experience a drop in performance of your vacuum system, resulting in office down-time and possibly costly repairs.


  • Reliability: When the vacuum system fails, your practice grinds to a halt! This can be embarrassing and expensive! As with any equipment product, quality varies from one manufacture to another.  Water injected vacuum systems have proven to be very reliable. Dry vacuum system technology is newer and evolving. Some dry vacuum products have had reliability issues.  Ask your distributor service technician about their experience on vacuum reliability and how it varies with brand and technology.


  • Noise level:  Both water injected and dry vacuums can be noisy. Noise may be a consideration in some installation situations. There are many ways to mitigate the noise problem however, including sound covers, room sound insulation and vibration isolation, so noise level should not be a prime consideration in your product choice. 


  • Size: Vacuum systems come in sizes to service facilities from one treatment room to 20 or more. When designing a vacuum  system, manufacturers consider the CFM air flow  from the vacuum. Rather than looking at vacuum usage by the number of treatment rooms however, manufacturers typically state the number of “users” that the vacuum is designed for. “Users” are typically defined as the dentists and hygienists using high volume evacuators and saliva ejectors simultaneously. The easiest way to size the vacuum properly is to simply add the number of dentists and hygienists that will be working simultaneously.  The current AND the future needs in the facility should be considered. There may only be one dentist and two hygienists using the vacuum now, but if there are plans to add another dentist or more hygienists, it may be prudent to buy a vacuum that accommodates the future expansion as well.  Depending on the vacuum system design, you may be able to buy a vacuum system that meets your current usage needs, but then add onto the system as your needs change. If the vacuum is under or over sized, it does not have any impact on reliability or maintenance since the vacuum normally runs  continuously all day regardless of the number of vacuum outlets are open. Note that there are some new dry vacuum designs what will switch on and change speeds as more vacuum outlets are opened. This concept should help to increase longevity of the product and reduce your utility bills.


  • Purchase cost: Pricing varies with system size, quality and with the technology used. Dry vacuums are normally more expensive, but have lower utility costs to operate. The water injected vacuum systems may be less expensive to purchase, but you will experience higher ongoing utility costs. 


This Buyers Advice article was authored by David Anderson, the President of Voice Market Research. For more information , see “About Us” 



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