Surface grinders are often used to smooth poured concrete surfaces after the forms have been removed. Grinding concrete generates a large amount of dust which is likely to contain high levels of crystalline silica and creates a hazard for everyone in the vicinity.  Vacuum dust controls exist for surface grinders.  These controls consist of a vacuum, with a disposable filter (a high efficiency particulate air, HEPA, filter is often an option and recommended where practical), attached to a shroud that is compatible with the grinder and partially encloses the blade.  The vacuum draws air and dust from the blade, the point of dust generation, into the shroud where it is transported through tubing into the vacuum's bag or reservoir. Cyclonic pre-separators, either as an integral part of the vacuum or as a separate unit, should be used to collect the majority of the particles before they reach the filters. The use of a cyclonic pre-separator reduces the amount of dust that collects on the filter, which increases the useful life of expensive filters and helps to maintain the vacuum’s initial airflow rate.

Pearl Abrasive Company Vacu-Guard dust containment systems for angle grinders

• Used with a variety of angle grinders and vacuums to reduce dust levels while grinding concrete surfaces
• Compatible with most Dewalt, Black & Decker, Bosch, Makita, Metabo, Milwaukee and Hitachi grinders (must specify grinder make and model when ordering)
• Optional carbide wear pads protect sliding surface from excessive wear, thus increase useful life
• Constructed of durable and light-weight aluminum

Hilti DG 150 Diamond Grinder System with Power Conditioner

• Used for concrete and mineral surface grinding
• Power requirements: 120 volts, 15 amps
• Vacuum take-off diameter: 1.42 inches (36 millimeters)
• Weight: 9 pounds
• Wheel speed (no load): 4,700 and 6,600 RPM
• Sound pressure level: 88 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA; at 85 dBA employees must be enrolled in a hearing conservation program

Hilti VC 300-17X wet/dry vacuum cleaner

• Air flow rate (maximum): 314 cubic feet per minute
• Length of vacuum hose: 16 feet
• Dust capacity: 17 gallons
• Weight: 63.1 pounds
• Filter cleaning: automatic, every 7.5 seconds
• Power requirements: 120 volts, 10 amps

 Dustcontrol, Inc. suction casings for diamond cup grinding discs

• Used with a variety of angle grinders and vacuums to reduce dust levels while grinding concrete surfaces
• Compatible with most angle grinders (must specify blade diameter, mounting collar diameter and mounting collar to grinding surface height when ordering)

Compatible Blastrac vacuums: BDC-1216, BDC-1324 and BDC-165P

• Filtration: main filter removes 99.7 percent of particles, a HEPA filter kit and replacement HEPA filters can be purchased

*Blastrac technical support staff has indicated that while the BDC-1216 works with the above mentioned grinders, the larger vacuums have significantly greater flow rates and provided noticeably better dust collection.

CS Unitec/FLEX LD1509FRD 5-inch lightweight concrete grinder with dust collection shroud

• Used to remove epoxy, paint, mastic, mud and other coatings from concrete surfaces
• Power Requirements: 120 volts, 11 amps
• Maximum blade diameter: 5 inches
• Maximum blade speed: 10,000 RPM
• Vacuum take-off diameter: 1-1/4 inches
• Weight: 6 pounds
• Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

 Compatible CS Unitec, Inc. vacuums: CS 1225 and CS 1500

• Air flow rate: 130 cubic feet per minute
• Water lift: 98 inches
• Available bags:
  • Plastic is ideal for concrete dust
  • Paper is ideal for general debris
  • Water permeable is ideal for concrete slurry
• Power requirements: 120 volts, 11 amps
• Filtration: standard filter removes 99.93 percent of 3.0 micron particles, HEPA filter can be purchased

Industrial Contractors Supply (ICS), Inc. Surface Grinding Dust Shrouds

• Used with a handheld grinder to reduce dust during the grinding and polishing of concrete
• Compatible with most Metabo, Hitachi, Makita, Bosch, Ryobi and Dewalt grinders (must specify grinder make and model when ordering)
• Constructed of durable steel with adjustable rubber seal along the edge
• Vacuum take-off diameter: 2 inches
• Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

Industrial Contractors Supplies, Inc. vacuums

• Maximum static pressure: 97 inches of water

Industrial Contractors Supplies, Inc. 30 Gallon HD Poly Cyclone Separator

• Cyclonic separator that can be connected to ICS DC-2-MOTOR or DC-3-MOTOR vacuums to remove larger particles and increase the time between changing vacuum bags and filters.
• Dust capacity: 140 pounds

Dustless Technologies DustBuddie Dust Containment Shroud for hand grinders

• Used with a handheld grinder for dust collection during surface grinding
• DustBuddie D1835 fits most 4 to 5 inch hand grinders, DustBuddie D1850 fits most 6 to 9 inch grinders
• Vacuum take-off diameter: 2 inches (with adapter)
• Constructed from light weight, see-thru, polycarbonate plastic
• Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

Bosch Dust Extraction Attachments for Surface Grinders

• Used with handheld grinders to reduce dust during concrete surface grinding
• Vacuum take-off diameter: 1-5/8 inches
• Bosch grinders compatible with dust extraction attachment 18SG-5E: 1800, 1801, 1803EVS, 1806E, 1810PS, 1810PSD, 1811PS, 1811PSD, 1821 and 1821D
• Bosch grinders compatible with dust extraction attachment 18SG-7: 1853-5, 1853-6, 1873-6, 1873-8, 1873-8D, 1893-6, 1893-6D, 1894-6 and 1894-6D

 Bosch Airsweep™ Wet/Dry Vacuum

• Air flow rate: 130 cubic feet per minute
• Water lift: 100 inches
• Power requirements: 120 volts, 11 amps
• Weight: 42 pounds
• Filtration: standard set of two filters remove 99.93 percent of 3.0 micron particles, set of HEPA filter can be purchased for approximately $200
• Sounds pressure level: 69 dBA

 Pullman-Ermator single phase electric dust extractors

• Filtration: cyclonic separator, coarse filter and HEPA filter capable of removing 99.97% of 0.3 micron particles (the most penetrating size)
• Sound pressure level: 75 dBA or less (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)

* Longopac® bag system uses a 70 foot long plastic tube that is divided and sealed at the desired length

** Greater area allows more time between filter cleaning or replacement

(Photo courtesy of Husqvarna AB Construction Division)

Pullman-Ermator three phase electric dust extractors

• Filtration: cyclonic separator, coarse filter and HEPA filter capable of removing 99.97% of 0.3 micron particles
• Dust collection: Longopac® bag system which uses a 70 foot long plastic tube that is divided and sealed at the desired length
• Sound pressure level: 75 dBA or less (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)

* Greater area allows more time between filter cleaning or replacement

(Photo courtesy of Husqvarna AB Construction Division)

Pullman-Ermator cyclonic pre-separators

• Remove approximately 90 percent of particulate and can be used with Pullman-Ermator or other dust extractors
• Dust collection: Longopac® bag system which uses a 70 foot long plastic tube that is divided and sealed at the desired length

(Photo courtesy of Husqvarna AB Construction Division)

(Photo courtesy of Husqvarna AB Construction Division)

Ventilation for construction tools is often misunderstood. There are some key concepts that can help:

• The vacuum must be located as close to the dust generation as possible to be effective. A shroud may be needed to contain the dust so the vacuum can capture it. The shroud must be kept as close to the work surface as is practical to provide adequate dust capture. The shroud should be connected to the vacuum with 2-inch, or greater, diameter tubing with a relatively smooth interior.
• The particles that can do the most damage in the lungs are small enough to penetrate the filters found on many shop vacuums. Additionally, some inexpensive shop vacuums pull the dust through the motors, which can destroy the vacuum on really dusty jobs, eliminating any initial cost savings.
• For dust containing harmful particles like silica, it is important to use as high efficiency filters as practical. The best available are called HEPA (High Efficiency Particle Air) filters because they capture 99.97% of the most penetrating particles. But HEPA filters also create a greater pressure drop and decrease in air flow rate because it is more difficult to pull air through these denser filters so capture velocity may be reduced. They also require pre-filters to extend the life of the HEPA filters, which are more expensive than other filters. Studies have shown that it may be more effective to direct the exhaust air out of the work area than to attempt to add HEPA filtration for a tool where it isn't an integral part already. HEPAs require routine cleaning or disposal of prefilters, which can cause exposures to those performing the filter maintenance.
• For operations that generate large amounts of dust, cyclonic collection units, if available, may be the best solution. Rather than require more expensive filters and bags that must be frequently changed, cyclonic units spin the particles and drop them into cheap bags that need to be replaced far less frequently because loading of the bags does not cause a pressure drop.
• Vacuum performance must be monitored on a regular basis. A vacuum with a pressure gauge allows for frequent and easy monitoring of air flow. For high dust generating tasks, dust caked on the filter may reduce flow to a level where it no longer provides adequate dust capture. Automatic and manual filter shakers, coarse pre-filters and cyclonic collections units are available with some vacuums and may help maintain the air flow rate.