Wet or dry vacuum?

Key facts

What is the actual difference?

EPA's WaterSense guidance explains it simply. Dry pumps don't use water to seal the vacuum; they use turbines or positive-displacement designs such as vane, claw or piston pumps. Liquid-ring pumps use a water ring inside the casing to form the seal, and that water picks up heat and impurities as it runs (EPA).

In the simplest wet systems, the seal and cooling water is discharged and replaced continuously. Recirculation kits can cut that. EPA estimates a full recovery system reduces water use by nearly 100%, and a partial system by about 50% (EPA). Midmark's wet-ring models ship with a by-pass valve factory-set to recycler mode (Midmark).

EPA puts dental office pumps at 1 to 4 horsepower (EPA). Multiply that by 0.5–1.0 gpm per hp and the run hours in your schedule, and the water difference becomes a real number.

How do they compare on cost?

Upfront, EPA notes that dry, air-cooled pumps "might be more expensive" but are about 30% more energy-efficient because they don't pump water along with air (EPA). Over the life of the pump, the comparison is purchase price against water, sewer and electricity.

Two cost items get missed. First, wet pumps are sensitive to water quality. Midmark warns that running without water, or with high-mineral or high-sediment water, can damage the pump or shorten its life, and says that isn't a warranty defect. It recommends a 50-micron filter, plus a mineral reducer kit in hard-water areas (Midmark). Second, both types need an amalgam separator if the office places or removes amalgam (EPA).

What plumbing does each one need?

Wet-ring (Midmark ClassicSeries example):

• Water supply via poly tubing, 20–120 psi, water at 35–80°F
• Suction line from the operatories (1" or 1½" hose depending on model)
• Separator drain to a P-trap with air gap or a floor drain, per local code
• 2" vent; odors, vapors and nitrous oxide vent out of the separator top

(Midmark)

Dry (A-dec QuietCore+ and Air Techniques Mojave examples):

• Drain hose to a floor sink of at least 10 gallons, or 20 gallons for dual or tandem systems (A-dec)
• Air Techniques asks for an open or vented floor drain that can take 10 gallons in 30 seconds, with 1½" Schedule 40 drain pipe (Air Techniques)
• 2" exhaust vented outside, shrouded and screened against rain and animals (A-dec)
• A washdown water line. A-dec requires it for offices that do endodontics and recommends it everywhere (A-dec)

The piping out to the operatories is similar for both. See running dental vacuum lines for slope and sizing.

What about power, space and noise?

Dry systems in the A-dec QuietCore+ line run on 220–240 VAC, single phase, with 20 A or 30 A breakers by model, and need a hardwired disconnect. Sound runs from 64.8 to 76.2 dBA, and the mechanical room must stay between 40 and 104°F (A-dec).

Midmark's wet-ring line offers 115 V or 208–230 V models on a 20 A breaker per pump, with the same 40–104°F room range (Midmark).

Electrical, heat and noise belong on the drawings before the mechanical room is sized. See dental operatory electrical requirements for the chair side.

Before you price either option, put the mechanical room on the plan. In Studio you can mark the floor sink, vent route and electrical for each pump type. The build-out cost & timeline calculator (free tool, coming soon) will hold both quotes side by side.

Does the chair care which one I pick?

Yes. A-dec's 511 chair guide lists different vacuum targets by system type: 10 ± 2 inHg at 9 scfm minimum for wet systems, and 4.5 ± 1 inHg at 12 scfm minimum for dry or semi-dry systems (A-dec 511). Tell the dealer which pump you're buying before the chair is configured. Per-chair specs are compared in dental chair utility requirements.

How do I size it?

By simultaneous users, not by room count. A-dec rates its dry vacuums at 5, 7, 10 or 12 maximum users (A-dec). Air Techniques publishes recommended simultaneous HVE/SE users per configuration (Air Techniques). Count how many chairs evacuate at once at peak, then add the rooms you plan to rough in for later.

From the MSP side, I'd add one thing. The A-dec QuietCore+ supports network connectivity, and A-dec asks for a 10/100 Ethernet drop or strong Wi-Fi at the vacuum (A-dec). Put a data drop in the mechanical room. When the compressor & vacuum sizing calculator launches (free tool, coming soon), it will turn your peak simultaneous-user count into a pump size.

How FloorStack helps

The free Studio plan places the mechanical room, vacuum, drains and data drop on your real floor plan, so your plumber and dealer work from one drawing. The compressor and vacuum sizing calculator is a free tool (coming soon) that will size pumps by simultaneous users. The build-out cost and timeline calculator, also a free tool (coming soon), will carry the choice into your budget. FloorStack is a vendor-neutral dental build-out platform and doesn't sell pumps. See the Dental Equipment Planning hub and the startup equipment list.

Free tools for this step

• Studio (live, free plan): place the mechanical room, drains and vents on your floor plan.
• Compressor & vacuum sizing calculator (free tool, coming soon): size the pump by simultaneous users.
• Build-out cost & timeline calculator (free tool, coming soon): budget the mechanical room.