Walk-behind milling machines or scarifiers with vacuum dust control

A walk-behind concrete scarifier or milling machine with vacuum dust collection reduces airborne dust during the removal of concrete or coatings from concrete.

Description:

Removing, roughening or resurfacing concrete with a walk-behind scarifier or milling machine generates a large amount of dust that may contain high levels of crystalline silica or other hazardous materials and creates a hazard for everyone in the vicinity. Vacuum dust controls are available for walk-behind concrete scarifiers.

These controls consist of a vacuum with a disposable filter (a high efficiency particulate air, HEPA, when practical) attached to a shroud surrounding the heads. The vacuum draws dust from the heads, the point of dust generation, and transports it to the collection unit. Capturing dust containing silica near the point of generation and removing it from the work environment reduces the concentration in the worker's breathing zone.

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. Cyclonic pre-separators reduce 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. 

OSHA recommends using systems to capture and control concrete dust; vacuum dust collectors are the most common. These methods can remove most airborne dust particles generated by milling. Using a cyclonic separator and a vacuum with filters greatly reduces the risk to operators and other workers on a site.
 

Edco Scarifiers

The Edco scarifiers use a vacuum port to remove dust from the scarifier’s drum.

ModelDrum Width (inches)Revolutions per MinutePower RequirementsWeight (pounds)Maximum Removal Rate (square feet per hour)
CPM-8-5B82,130230/460 volts, 12/6 amps (3 phase)220350 – 500
CPM-8-9H82,150gasoline, 9 horsepower190350 – 500
CPM-10-7.5B102,344230/460 volts, 17.4/8.7 amps (3 phase)287500 – 700
CPM-10-13H102,446gasoline, 13 horsepower267500 – 700
  • Removal Depth per Pass: 1/8 inch
  • Sound Pressure Level: greater than 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)
     

Edco Vacuum Systems

ModelsPower RequirementsAirflow (cubic feet per minute)Maximum Static Pressure (inches of water)Collection Capacity (gallons)Weight (pounds)
Vortex 200110 volts, 16 amps20094990
Vortex 290

110 volts,

19 amps

290759169
  • Cast-composite material guaranteed for life not to crack
  • Differential pressure gauge to indicate when filters should be replaced
  • HEPA filter capable of removing 99.97% of 0.3 micron particles (the most penetrating size)
  • Vacuum Port Diameter: 3 inches
     

Kut-Rite Scarifiers

The Kut-Rite scarifiers use a swiveling vacuum port for dust collection and are designed to be paired with a Klean-Rite vacuum system.

ModelDrum Width (inches)Power RequirementsWeight (pounds)Maximum Removal Rate (linear feet per hour)
KR8HD Gas8gasoline, 5.5 horsepower174200-400
KR8HD Electric8120 Volts, 24.8 amps (1 phase)205200-400
KR10 Gas10gasoline, 5.5 horsepower293450-600
KR13 Gas13gasoline, 11 horsepower423450-600
  • Removal Depth per Pass: 1/8 inch
  • Sound Pressure Level: not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)
     

Klean-Rite Vacuum Systems

ModelsPower RequirementsAirflow (cubic feet per minute)Maximum Static Pressure (inches of water)Weight (pounds)
RF21110 volts, 15.5 amps18011075
RF31120 volts, 14.6 amps28080150
RF32220 volts, 15.5 amps550110150
  • Collection Capacity: up to 70 pounds
  • Filtration: filters feature Ultra-Web technology that enables the reverse flow units to work at maximum
  • Vacuum Port Diameter: 3 inches
     

Smith Scarifiers

ModelDrum Width (inches)Power RequirementsWeight (pounds)Removal Depth per Pass (inches)Maximum Removal Rate (square feet per hour)
SPS1010gasoline, 13 horsepower2501/4700
FS300D15.3gasoline, 13 horsepower4953/8850
  • Sound Pressure Level: greater than 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)
     

Smith Vacuum Systems

ModelWeight (pounds)
MV-600A128
MV-1000S139
  • Power Requirements: 220 volts, single phase, 20 amps
  • Airflow: 330 cubic feet per minute
  • Maximum Static Pressure: 118 inches of water
  • Filtration: cyclonic pre-separator (MV-1000S only), cyclonic separator inside vacuum, and HEPA filter capable of removing 99.97% of 0.3 micron particles (the most penetrating size)
  • Filter Cleaning: automatic shaking
  • Sound Pressure Level: 75 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)

Descobrader Model 120.223 Scarifier

  • Drum Width: 5.25 inches
  • Power Requirements: 220 volts, 16 amps
  • Maximum Removal Rate: 400 square feet per hour
  • Removes up to 0.5 inches thick
  • Vacuum Port Diameter: 3 inches
  • Sound Pressure Level: not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

Blastrac BMP-335EHY Scarifier

The Blastrac BMP-335EHY scarifier is optimally paired to a Blastrac BDC-3140DBP vacuum system.

  • Drum Width: 13.2 inches
  • Revolutions per Minute: 1,000
  • Power Requirements: 460 volts, 32 amps, 3 phase
  • Weight: 895 pounds
  • Maximum Removal: 570 square feet per hour
  • Removal Depth per Pass: 1/8 inch
  • Sound Pressure Level: not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)
     

Blastrac BDC-3140DBP Vacuum System

  • Power Requirements: 230 volts, 15.6 amps, 3 phase (single phase option)
  • Collection Capacity: up to 200 pounds
  • Filtration: HEPA filter capable of removing 99.97% of 0.3 micron particles (the most penetrating size)
  • Filter Cleaning: automatic air-pulse cleaning system
  • Maximum Static Pressure: 90 inches of water
  • Airflow: 300 cubic feet per minute
  • Weight: 507 pounds
  • Vacuum Port Diameter: 2, 2.75, and 3 inches

Pullman-Ermator USA Single Phase Electric Dust Extractors

 (Photo courtesy of Husqvarna AB Construction Division)

  • Dust Collection: Longopac® bag system (except for S1400) which uses a 70 foot long plastic tube that is divided and sealed at the desired length
  • 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)
ModelsAir Flow Rates (cubic feet per minute)Maximum Static Pressure (inches of water)Filter Area (coarse/HEPA) (square feet**)HorsepowerPower RequirementsWeight (pounds)
S13129100(N/A)/91.7120 volts, 9.8 amps or 230 volts, 4.9 amps66
S140013811011/92.2120 volts, 13.5 amps95
S2625810018/183.4120 volts, 19.6 amps103
S3635311050/185.1220 volts, 14.8 amps134


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

Pullman-Ermator USA Three Phase Electric Dust Extractors

 (Photo courtesy of Husqvarna AB Construction Division)

  • Filtration: cyclonic separator, coarse filter and HEPA filter capable of removing 99.97% of 0.3 micron particles (the most penetrating size)
  • Dust Collection: Longopac® bag system which uses a 70 foot long plastic tube that is divided and sealed at the desired length
  • Maximum Static Pressure: 110 inches of water
  • Sound Pressure Level: 75 dBA or less (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)
ModelsAir Flow Rates (cubic feet per minute)Available Hose Diameters (inches)Filter Area (coarse/HEPA) (square feet*)HorsepowerPower RequirementsWeight (pounds)
T75003532 or 324.8/53.810.4230 volts, 24.2 amps417
T86003532 or 324.8/53.810.4480 volts, 11.9 amps439
T12600647341/10817.4480 volts, 21 amps716


* Greater area allows more time between filter cleaning or replacement

Pullman-Ermator USA Cyclonic Pre-Separators

(Photo courtesy of Husqvarna AB Construction Division)

  • Removes approximately 90 percent of particulates 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
ModelsInlet Diameter (inches)Weight (pounds)
C3000249
C55003130

(Photo courtesy of Husqvarna AB Construction Division)


Risks Addressed:

Silica dust exposure may cause silicosis or lung scarring with prolonged exposure.  Silicosis is an incurable, sometimes fatal, disease. The NIOSH Recommended Exposure Limit (REL) is 0.05 mg/m3 (or 50 micrograms per cubic meter) as a time-weighted average concentration for up to a 10-hour workday during a 40-hour workweek. This is one-fourth of the current OSHA standard, but still twice the American Conference of Governmental Industrial Hygienists (ACGIH) recommended Threshold Limit Value (TLV) of 0.025 mg/m3. In August 2013, OSHA proposed a revised silica standard of 0.05 mg/m3. Silica has also been associated with lung cancer and chronic obstructive pulmonary disease (COPD) (Rice, 2002).

Echt et al. conducted a study to determine respirable dust and silica concentrations while using a walk-behind concrete scabbler, a machine with similarities to a scarifier, during parking deck construction.  Ten personal breathing zone samples were collected while the scabbler was used without dust controls.  Five of the samples contained less respirable silica than the method can reliably detect (possibly due to wind or blockage of the sampler inlet by the worker’s clothing).  The remaining five sample results were well above the NIOSH REL and ACGIH TLV for respirable silica and ranged from 0.48 to 2.1 mg/m3 (Echt, 2002).

Silicosis symptoms include: chronic cough, shortness of breath when exercising, severe breathing difficulty, weight loss and fever.  People with silicosis are also at a high risk for developing tuberculosis (TB).  Although there is no specific treatment for silicosis, the source of the silica must be removed to ensure the disease does not get worse (PubMed, 2009).


How Risks are Reduced:

These controls consist of a vacuum with a disposable filter (a high efficiency particulate air, HEPA, when practical) attached to a shroud surrounding the tool’s head. The vacuum draws dust from the head, the point of dust generation, and transports it to the collection unit. Capturing dust containing silica near the point of generation and removing it from the work environment reduces the concentration in the worker's breathing zone.

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.  Cyclonic pre-separators reduce 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.

Local exhaust ventilation will capture dust. Although exposure is not reduced to zero, substantial reduction is expected. This depends on the vacuum’s ability to maintain adequate air flow for the shroud and task, the shroud configuration, the work rate and the extent to which workers are exposed to re-suspended dust. While there are no published sampling data on these specific tools, evidence indicates exposure to respirable silica can be significantly reduced through the use of vacuum dust controls.

The use of vacuum dust controls has been proven effective for concrete surface grinding, a process with similarities to milling. Compared to uncontrolled grinding, vacuum dust controls with HEPA filtration reduced respirable silica concentrations by 99%.  Dust concentration was not affected by either orientation of the grinding surfaces or the length of sampling time (Akbar-Khanzadeh, 2010).

Blastrac states that its dust collection systems matched with the correct scarifier “reduce airborne dust and particulate to provide a cleaner work environment, make surface preparation atmospheres more pleasant, and improve safety.” The systems create a cleaner work setting and “a cleaner work environment is safer and provides for increased productivity from operators as well as other workers in the same area.”


Effects on Productivity:

Vacuum dust collectors are expected to have a positive effect on productivity and improve the quality of the work by removing large amounts of dust, which provides a cleaner environment for operators and reduces the effort and time required for clean-up.  Dust capture avoids exposing other workers, members of the public, adjacent property, cars and building occupants, which can increase liability and time-consuming disputes.  Improved worker comfort is a result of reduced airborne dust which may in turn result in less fatigue for the worker and greater productivity.  In some cases, particularly where work is intermittent or in an area with general ventilation, use of dust collectors may be adequate to reduce the need to wear a respirator, and the need for an employer’s respiratory protection program. 

Some additional issues should be considered.  Changing vacuum bags takes time, which will depend on the amount of milling being done and the size of the vacuum bag or hopper.  Workers will need to adapt to working with a vacuum hose attached to the tool.


Additional Considerations:

Ventilation for construction tools is often misunderstood. These 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 is 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 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 0.3 micron particles (the most penetrating size).  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.
  • For operations that generate large amounts of dust, a cyclonic collection unit may be the best solution.  Cyclonic collection units spin the particles and drop them into plastic bags.  The plastic bags are less expensive than many vacuum bags and the bags 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.  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 collection units are available with some vacuums and may help maintain the air flow rate.

Large electric vacuums commonly require electrical circuits that can provide greater than 20 amps and/or more than 120 volts.  Cords and extensions must be rated for the tool's power requirements, be inspected regularly and used in combination with ground fault interrupt circuits.

The use of diesel and particularly gasoline-powered generators and equipment poses the risk of carbon monoxide exposure, especially in areas where airflow is reduced.  Steps to control exposure are important because the gas is invisible, odorless and tasteless.  Poisoning by carbon monoxide can occur quickly indoors, but working outdoors does not ensure operators won’t be overcome.  Small, inexpensive personal monitors should be worn by the operator to warn of unacceptable exposures.  Equipment should not be left idling to cut down on carbon monoxide and to conserve fuel.

Concrete scarifiers and milling machines can generate sound levels that are greater than 90 decibels, the OSHA Permissible Exposure Limit (PEL), and hazardous.  Hearing protection should be worn when using concrete scarifiers unless an industrial hygienist has conducted noise monitoring and indicated that hearing protection is not required.

As is the case with any construction equipment, users should follow manufacturer safety recommendations and comply with any applicable local, state or federal regulations.


Contributors:

Taylor Kingston and Michael R. Cooper - Aria Environmental, Inc.
Bruce Lippy - CPWR

Availability

Pullman-Ermator, Inc.
To obtain information, visit single phase electric dust extractorsp://www.ermatorusa.com or contact 1-855-736-2869 hcpcustomer.service@husqvarna.com

Smith Walk-Behind Scarifiers and Vacuum Systems
To obtain information, visit Smith Manufacturing Co., Inc. Scarifiers and Smith Manufacturing Co., Inc. Vacuum Systems or contact 1-800-653-9311 cutters@smithmfg.com

Descobrader Walk-Behind Scarifier and Vacuum System
To obtain information, visit Model 120.223 Scarifier and Desco Vacuum Systems or contact 1-800-337-2648

EDCO Walk-Behind Scarifiers and Vacuum Systems
To obtain information, visit EDCO, Inc. Walk-behind Scarifiers and EDCO, Inc. Vacuum Systems or contact 1-800-638-3326 info@edcoinc.com

Kut-Rite Walk-Behind Scarifiers and Vacuum Systems
To obtain information, visit Scarifiers and Vacuum Systems or contact 1-877-786-5067

Return on Investment

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