Solution Summary: Walk-Behind Concrete Scabblers with Vacuum Dust Control
A walk-behind concrete scabbler with vacuum dust control reduces dust exposure during the removal or roughening of concrete.
Description:
Removing or roughening concrete with a walk-behind scabbler generates a large amount of dust that may contain high levels of crystalline silica and creates a hazard for everyone in the vicinity. Concrete scabblers with local exhaust ventilation are available.
These controls consist of a vacuum with a disposable filter attached to a shroud surrounding the heads or bits. A high efficiency particulate air, HEPA, filter is often an option and recommended where practical. The vacuum draws air and dust from the heads, the point of dust generation, and transports them through tubing from the shroud to 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. A cyclonic pre-separator spins the air and dust, forcing particles to the outside of a cone-shaped portion of the vacuum and then down into a bag or hopper. 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.
EDCO, Inc. Pneumatic Scabblers
- Used for removing spalled or deteriorated concrete, roughening surfaces for new overlays or coatings, reducing high spots or leveling uneven joints, sidewalk trip hazard repair, removing epoxy, creating slip-resistant surfaces, texturing parking garage ramps and breaking up ceramic tile.
- Points per head: 5 (9 point heads are available for the CD-5 model)
- Head impacts per minute: 1,200
- Vacuum take-off diameter: 2 inches
- Sound pressure level: Greater than 92 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)
| Models | Compressed Air Supply Requirements | Maximum Removal Rate, square feet | Removal Depth per Pass, inches | Weight, pounds |
| 3-Head Scabbler (CD-3) | 100 cfm at 100 psi | 200 | 3/16 | 165 |
| 5-Head Scabbler (CD-5) | 160 cfm at 100 psi | 250 | 1/4 | 278 |
cfm = cubic feet per minute
psi = pounds per square inch
Compatible EDCO, Inc. vacuums: Vortex-200, Vortex-290 and Vortex-300
- Dust capacity: 9 gallons
- Filtration: main filter removes approximately 98 percent of particles, optional HEPA filter kit can be purchased
| Models | Air Flow Rates, cubic feet per minute | Maximum Static Pressure, inches of water | Vacuum Power Requirements | Vacuum Weight, pounds |
| Vortex-200 | 200 | 94 | 120 volts, 16 amps | 90 |
| Vortex-290 | 290 | 75 | 120 volts, 19 amps | 169 |
| Vortex-300 | 300 | 95 | gasoline | 285 |
Pentek Moose Concrete Scabbler
- Used for decontamination of large floor slabs in environments which require stringent control of airborne contamination and debris
- Scabbling bits/heads: 7, each 2-1/4 inches in diameter
- Points per bit: 7, tungsten carbide-tipped
- Cutting depth: 1/16 to 3/16 of an inch
- Cutting width:18 inches
- Bit/head impacts per minute: 1,200
- Production rate: 250 to 450 square feet per hour at 1/16-inch surface removal
- Electrical power requirements: 110 volts, 15 amps, single phase (or 240 volts, 7 amps)
- Air consumption: 315 cubic feet per minute at 90 pounds per square inch
- Vacuum take-off diameter: 2 inches
- Weight: 1,650 pounds
- Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)
Pentek Squirrel II Concrete Scabbler
- Used to remove hazardous materials from cracks in concrete floors and slabs
- Scabbling bits/heads: 1, each 2-1/4 inches in diameter
- Points per bit: 4 tungsten carbide-tipped
- Cutting width:7/8 inches
- Maximum cutting depth: 2 inches
- Production rate: 50 to 60 linear feet per hour at 1/4-inch surface removal
- Air consumption: 38 cubic feet per minute at 90 pounds per square inch
- Vacuum take-off diameter: 2-1/2 inches (requires adapter to connect to Vac-Pac vacuum system)
- Compatible with Pentek’s Vac-Pac vacuum systems
- Weight: 180 pounds
- Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)
Pentek Squirrel III Concrete Scabbler
- Used to pulverize, clean and texture concrete surfaces. It can operate in tight spaces such as corners, wall/floor joists, equipment pedestals, steps and under protruding equipment.
- Scabbling bits/heads: 3, each 1-3/4 inches in diameter
- Points per bit: 9, tungsten carbide-tipped
- Cutting width:6 inches
- Production rate: 20 to 30 linear feet per hour at 1/16-inch surface removal
- Air consumption: 60 cubic feet per minute at 90 pounds per square inch
- Vacuum take-off diameter: 1-1/2 inches
- Compatible with Pentek’s Vac-Pac vacuum systems
- Weight: 50 pounds
- Scabbling head vibration isolation technology completely eliminates operator fatigue associated with conventional scabbling equipment.
- Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)
Pentek Air-Powered VAC-PAC High Performance HEPA Vacuum Systems
- Maximum static pressure: 100 inches of water
- Primary coarse filters:
- Eight inches in diameter
- Two for models 6, 9, 12 and 15 and three for models 18, 21 and 24
- Removes approximately 95 percent of 1 micron particles,
- Secondary HEPA filter (2 square feet) removes 99.97 percent of 0.3 micron particles
- Debris is deposited in a standard 55-gallons drum (23-gallons drums for use with 55-gallon overpacks are available)
- Features: automatic full-drum level alarm, connections for multiple hoses
- Weight: 750 pounds
| Models | Air Flow Rates, cubic feet per minute | Compressed air supply requirements, cubic feet per minute at 85 pounds per square inch |
| Model 6 | 150 | 70 |
| Model 9 | 225 | 105 |
| Model 12 | 300 | 140 |
| Model 15 | 375 | 175 |
| Model 18 | 450 | 210 |
| Model 21 | 525 | 245 |
| Model 24 | 600 | 280 |
Pentek Electric-Powered VAC-PAC High Performance HEPA Vacuum Systems
- Primary coarse filters:
- Eight inches in diameter
- Two for models 10 and 13 and three for model 22
- remove approximately 95 percent of 1 micron particles,
- Secondary HEPA filter (2 square feet) removes 99.97 percent of 0.3 micron particles
- Debris is deposited in a standard 55-gallons drum (23-gallons drums for use with 55-gallon overpacks are available)
- Features: automatic full-drum level alarm, connections for multiple hoses
- Automatic self-cleaning by reverse-flow pulses of high pressure air
| Models | Air Flow Rates, cubic feet per minute | Maximum static pressure, inches of water | Rated Motor Horsepower | Weight, pounds |
| Model 10 | 250 | 93 | 5 | 950 |
| Model 13 | 325 | 100 | 7.5 | 1,100 |
| Model 22 | 550 | 102 | 15 | 1,250 |
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)
| Models | Air Flow Rates, cubic feet per minute | Static Pressure, inches of water | Dust Collection | Filter Area (coarse/HEPA), square feet** | Horsepower | Power Requirements | Weight, pounds |
| S1200 | 118 | 90 | Longopac® bag system* | 6.6/9.1 | 1.7 | 120 volts, 9.6 amps or 230 volts, 4.4 amps | 62 |
| S1300 | 118 | 90 | 3.4 gallons | 16/9.1 | 1.7 | 120 volts, 9.6 amps or 230 volts, 4.4 amps | 62 |
| S2400 | 235 | 90 | Longopac® bag system* | 11/18.34 | 3.4 | 120 volts, 19.2 amps or 230 volts, 8.8 amps | 62 |
| S2800 | 235 | 90 | 9.8 gallons | 11/18 | 3.5 | 120 volts, 8.8 amps | 99 |
* 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)
| Models | Air Flow Rates, cubic feet per minute | Static Pressure, inches of water | Available Hose Diameters, inches | Filter Area (coarse/HEPA), square feet* | Horsepower | Power Requirements | Weight, pounds |
| T3000 | 153 | 125 | 2 | 23/6.6 | 4.8 | 230 volts, 7.5 amps | 183 |
| T3500 | 188 | 125 | 2 or 3 | 15.1/26.9 | 4.8 | 230 volts, 7.5 amps | 313 |
| T7500 | 353 | 110 | 2 or 3 | 24.8/53.8 | 10.4 | 230 volts, 24.2 amps | 417 |
| T8600 | 353 | 110 | 2 or 3 | 24.8/53.8 | 10.4 | 480 volts, 11.9 amps | 439 |
| T12600 | 647 | 110 | 3 | 41/108 | 17.4 | 480 volts, 21 amps | 716 |
* Greater area allows more time between filter cleaning or replacement
(Photo courtesy of Husqvarna AB Construction Division)
Pullman-Ermator cyclonic pre-separators
- Removes 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
| Models | Inlet Diameter, inches | Weight, pounds |
| C3000 | 2 | 49 |
| C5500 | 3 | 130 |
(Photo courtesy of Husqvarna AB Construction Division)
(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 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 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 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).
How Risks are Reduced:
The scabbler head is enclosed in a shroud with a connection for a vacuum system. When a vacuum system is connected to the shroud, air is drawn into the shroud and past the heads, capturing dust and silica at the point of dust generation. The system captures dust and silica near the source, reducing concentrations in the worker's breathing zone and his or her exposure.
Using local exhaust ventilation will visibly suppress dust, but the extent that it reduces the small, respirable particles is unclear, without testing. Although exposure is not reduced to zero, substantial reduction is expected. This is dependent on the vacuum’s ability to provide and maintain adequate air flow for the shroud and task, the shroud configuration, the work rate and the extent to which workers are exposed to resuspended dust after it dries. While there is no published sampling data on these specific tools, evidence indicates exposure to respirable silica can be significantly reduced through the use of local exhaust ventilation.
Pentek states that when using its Moose scabbler with integral vacuum, “essentially 100% of the airborne particulate and over 99.5% of heavier solids are captured at the cutting tool surface.”
Pentek states that its Squirrel II and Squirrel III scabblers with Vac-Pac vacuum systems “provide for high efficiency control of dust, debris and airborne contamination.” The systems “can minimize or eliminate the need for the respiratory protection” and “the need to protect nearby operating equipment from cross-contamination due to dust and debris.”
Effects on Productivity:
Vacuum dust control systems can have either positive or negative effects on productivity, but definitely improve the quality of the work by capturing large amounts of airborne dust, which allows a cleaner, more efficient means of removing surface concrete and coatings.
Dust capture also reduces site cleanup times. 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 scabbler use is intermittent, vacuum dust control may be adequate to reduce the need to wear a respirator and for an employer respiratory protection program.
Some additional issues should be considered. Changing vacuum bags takes time, which will depend on the amount of scabbling 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. 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 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 disposal of prefilters, which can cause exposures to those doing the filter change out.
- 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. 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.
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 compressors 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.
Walk-behind concrete scabblers frequently 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 scabblers 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 scheduled maintenance and safety recommendations and comply with any applicable regulations.
Availability
EDCO, Inc. Pneumatic Scabblers and Vacuums
To obtain information, visit http://edcoinc.com
or contact 1-800-638-3326 info@edcoinc.com
Pentek concrete scabblers and vacuum systems
contact 1-412-262-0725 info@pentekusa.com
Pullman-Ermator Inc.
To obtain information, visit single phase electric dust extractors and three phase electric dust extractors and c-line pre seperators
or contact 1-855-736-2869 info@ermatorusa.com
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