|
 |
| Solution: Hand-held Grinders with Wet Dust Suppression | |
 |
 |
|
 |
| Description: |
Hand-held surface grinders are often used to smooth poured concrete surfaces after the forms have been removed. Hand-held grinders are also used to smooth granite, marble and other natural stone. Grinding concrete and natural stone 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.
Using water to suppress the dust may be easier than using local exhaust ventilation in some circumstances, and is an important dust control option to consider. These engineering controls use a pump or line pressure to deliver water to the grinding surface where it combines with particles and reduces airborne dust levels.
If properly designed and used, exposures can be significantly reduced. If use of grinders is brief and intermittent, this may reduce exposures enough that a respiratory protection program isn’t required. Continuous use may exceed the OSHA Permissible Exposure Limit, even with the use of wet dust suppression, however.
Intertool DS 175 7-inch planetary polisher with wet dust suppression
 
Intertool DS 175 with three 3-inch planetary discs
Intertool DS 301 12-inch planetary polisher with wet dust suppression
Intertool DS 301 with three 5-inch planetary discs
FLEX LW 1509 Wet Grinder
MK Diamond Products, Inc. MK-1503-Air pneumatic polisher with wet dust suppression
MK Diamond Products, Inc. MK-1503-S electric polisher with wet dust suppression
|
||
| Risks Addressed: |
Grinding concrete, stone and masonry materials containing crystalline silica is a high dust activity that in the absence of controls would place workers at risk of lung disease, cancer, chronic obstructive pulmonary disease (COPD), lung scarring and silicosis with prolonged exposure. Silicosis is an incurable, sometimes fatal disease. Such disease is well documented in the Vermont granite quarries and stone cutting sheds, and in construction operations. 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-half of the OSHA standard when the dust is pure silica, but still twice the ACGIH-recommended threshold limit value (TLV) of 0.025 mg/m3. |
||
| How Risks are Reduced: |
Water is delivered to the grinding disc where it combines with particles created by grinding of stone, concrete and masonry materials and the now larger particles settle. Silica in the concrete and masonry materials is only hazardous if it is inhaled and is not hazardous for skin contact. As long as the dust does not become airborne, the hazard is reduced. The extent to which these tools are effective in meeting recommended exposure limits has not been evaluated.
|
||
| Quality of Evidence (Risk Reduction): |
|
||
| Quality of Evidence Explanation (Risk Reduction): |
Using water will visibly suppress dust, but the extent that it reduces the small, respirable particles is unclear, without additional testing. Although exposure is not reduced to zero, substantial reduction is expected. This is dependent on the amount of water used, how effectively it prevents suspension of particles in the air, rotational speed of the grinder 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 wet methods. In a survey of silica exposure during fabrication of granite countertops, Simcox et al. observed an average silica concentration of less than 0.07 milligrams per cubic meter during the use of water-fed grinders. They concluded “wet processes significantly reduced worker exposure to respirable crystalline silica and, in all cases, to below the state of Washington’s PEL of 0.1 mg/m3.”
In a study of granite processing facilities, Wickman and Middendorf stated that “the workplace controls, which are typically wet methods, implemented in the granite industry have been generally effective in reducing employees' exposures to below the OSHA PEL.” They recommended that “use of these controls should be implemented and enforced in other workplaces, such as rock drilling and abrasive cutting of concrete, where silica exposures remain problematic.”
|
||
| Effects on Productivity: |
Wet dust suppression systems can have either positive or negative effects on productivity, but definitely improve the quality of the work by suppressing large amounts of airborne dust, which allows a cleaner, more efficient means of grinding. Dust suppression also reduces site cleanup times. Dust suppression 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 grinder use is intermittent, wet dust suppression may be adequate to reduce the need to wear a respirator, and the need for an employer respiratory protection program.
Some additional issues should be considered. Time may be required to allow concrete and masonry materials to dry after grinding and before subsequent work, which will depend on the material, the amount of water used and the application. The grinder needs to be located near a water tank or another source of water.
|
||
| Quality of Evidence (Effects on Productivity): |
|
||
| Quality of Evidence Explanation (Effects on Productivity): |
While there is very little information on productivity from manufacturers or independent studies, safety and health experts believe the use of these controls will lead to an increase in productivity by reducing dust-related hazards and provide a cleaner work environment. |
||
| Return on Investment: | To calculate the return on investment (ROI) for your specific application, please visit our Return on Investment Calculator. While a specific ROI example has not been developed for this particular solution, the ROI Calculator provides a useful tool and guidance on how to generate your own on investment analysis. | ||
| Availability: |
Intertool: DS 175 7-inch and Intertool DS 301 12-inch planetary polisher with wet dust suppression
Flex North America, Inc.: LW 1509 and LW 1703 S wet grinder
MK Diamond Products, Inc. MK-1503 and MK-1503-S Air polisher with wet dust suppression
To locate a distributor visit http://www.mkdiamond.com/global/us_dist.html or contact 1-800-421-5830 or CustomerService@MKDiamond.com
|
||
| Additional Considerations: |
Grinding of concrete or masonry performed in the state of California must employ engineering controls, either wet methods or local exhaust ventilation, unless the employer can show that exposures are below the permissible exposure limit (subchapter 4, article 4, section 1530.1). New Jersey has a similar prohibition of dry cutting or grinding of masonry (Chapter 172). The use of water controls may result in wet and slippery ground and walking surfaces. During cold weather this may lead to the formation of ice and an increased risk of slips, trips and falls. Grinding debris that is not removed from the work area while wet may become airborne once dried, posing an inhalation hazard to anyone in the area. Maintaining a work area free of debris and excess water reduces the risk of these hazards.
The use of water as a dust control increases the risk of shock when electricity is used in the same area. Electrical cords and extensions must be rated for the tool's power requirements, be regularly inspected, replaced when damaged, and used in combination with ground fault interrupt circuits.
The use of gasoline and diesel-powered generators, compressors, pumps and other equipment poses the risk of carbon monoxide exposure, particularly 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.
Hand-held grinders 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 grinders 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.
|
||
| Hazards Addressed: |
|
||
 |
| |
 |
Home 
Feedback
FAQ
Volunteer
About
View Intro
Resources
|
