Downdraft Tables for Woodworking

A downdraft table is a dust control device that reduces airborne wood dust during woodworking operations.

Description:

A downdraft table is an engineering control that can reduce exposure to wood dust. Downdraft tables are workbenches with slots or holes in the horizontal work surface. Air is drawn past the workpiece and into the slots or holes by a vacuum, which is either attached via the extraction port or built into the table, capturing dust near the point of generation. The wood dust is then collected and removed from the work environment, reducing the concentration in the worker's breathing zone and the opportunity for skin contact.

A wood dust capture and control system is recommended by OSHA and is commonly used in the form of a vacuum dust collector. These methods allow for the safe removal of most airborne dust particles that result from woodworking. Using a vacuum with filters, instead of ventilating to the outdoors greatly reduces the risk to other workers on a site. However, wood dust control by means of exhausting to the outdoors may be acceptable.
 
Dust control systems are a solution to the constant dust and debris created by wood workers. A permanent dust ventilation control may be the most effective way to remove the airborne particles, but the portable dust collectors provide a solution for situations where fixed ventilation systems are not feasible.
 
Air Dynamics Air Wolf High Performance Downdraft Table

 

 

 

 

 

 

 
The Air Wolf downdraft table is available with single and 3 phase motors. (Photo courtesy of Air Dynamics Industrial Systems Corporation)
 
 
  • Cost: $6,800 (verified 5/2011)
  • Work Surface Dimensions: 36 x 48 inches
  • Work Surface Height: 34 inches
  • Airflow Rate: 2,400 cubic feet per minute
  • Power Requirements: 120/240 volts, 24/12 amps (single phase); 230/480 volts, 6.8/3.4 amps (3 phase)
  • Weight: 300 pounds
  • Filtration Efficiency: 3 filters rated to remove 80% of 9.0 micron particles followed by 2 filters rated to remove 99.99% of 0.5 micron particles. HEPA filter is optional
  • Automatic Pulse-Jet filter cleaning
  • Differential pressure gauge, which can be used to monitor air flow
  • Sound Pressure Level: 75 dBA at 5 feet (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)
 
Denray Downdraft Table – Model 2872
 
 
 
 
 
 
 
 
 
 
 
 
 
 


The Denray Model 2872 downdraft table uses a tube filtration system. (Photo courtesy of Denray Machine Inc.)
  • Cost: $3,200 – 3,300 (verified 4/2011)
  • Work Surface Dimensions: 28 x 72 inches
  • Work Surface Height: 34.5 inches
  • Airflow Rate: 3,400 cubic feet per minute
  • Power Requirements: 120/220 volts, 18/9 amps (single phase), 230/460 volts, 6.5/2.8 amps (3 phase)
  • Weight: 490 pounds
  • Filter Efficiency: 99% at 1 micron, optional HEPA filter is capable of removing 99.97% of 0.3 micron particles (the most penetrating size)
  • Sound Pressure Level: 77 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)
 
DualDraw Flat Top Downdraft Tables
 

A flat top downdraft table by Dual Draw. (Photo courtesy of Dual Draw)
 
All DualDraw downdraft tables have one or two replaceable 24 x 24 x 4 inch multipleat filters. 
  • Filter Efficiency: 95% for 0.7 micron particles, optional HEPA filter is capable of removing 99.97% of 0.3 micron particles (the most penetrating size)
  • Work Surface Height: 34 inches
  • Sound Pressure Level: 70 to 78 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)
 
Model
Work Surface Dimensions (inches)
Airflow Rate (cubic feet per minute)
FT3036
30 x 36
2,000
FT3048
30 x 48
2,500
FT3060
30 x 60
2,500
FT3060A
30 x 60
4,000
FT3072
30 x 72
2,500
FT3072A 30 x 72 4,500
FT3096 30 x 96 5,000

In addition to flat top models, please visit the manufacturer for other types of downdraft tables.

 
Downdraft Table with Vented Back Stop. (Photo courtesy of Dual Draw).
 

Risks Addressed:

Exposure to wood dust in the workplace has several associated hazards. Wood dust irritates the eyes, nose and throat, in addition leads to pulmonary function impairment.  Western red cedar dust is considered a human carcinogen and has also been shown to cause asthma.  Significant accumulation of fine wood dust particles can also be a fire and explosion hazard in the workplace.

The woodworking industry creates significant amounts of wood dust.  The dust generated from saws, sanders, routers, etc. is generally not controlled, and workers exposed to wood dusts have experienced a variety of adverse health effects such as eye and skin irritation, allergies, reduced lung function, asthma, and nasal cancer.  Excessive amounts of dust can also inhibit sight within the work area creating hazardous conditions for not only the worker, but also others within the work environment.  By using dust control methods, exposure can be significantly reduced.  For example, sanding is one of the largest producers of respirable dust, but with the use of controls, dust emissions were reduced by 66 to 98%.  Additional controls, such as downdraft tables, are a means for further reducing exposure, which primary controls fail to capture (NTP, 2000).
 
Spee et al. performed task-based monitoring of 26 carpenters at 13 building projects to measure exposure to wood dust. Eight hour time-weighted average (TWA) exposures to wood dust ranged from 0.8 to 11.6 mg/m3 with a geometric mean (GM) of 3.3 mg/m3 and a geometric standard deviation (GSD) of 2.1.
 
Numerous studies in various countries have addressed whether Hodgkin’s Disease (HD) is linked to wood dust exposures.  Studies involving those who have already died from the disease, those who currently have the disease and woodworkers who were believed to be at risk of getting the disease were conducted.  No study included sufficient information to find a correlation between length of employment, type of position, exposure to certain products, or contact with chemical agents that may be used in woodworking and HD.  These investigations have shown that those with the greatest risk are among the carpentry and lumbering occupations. In the end, twelve studies were looked at, and five yielded statistically significant relationships between woodworking and Hodgkin’s disease (McCunney, 1999).
 
The American Conference of Governmental Industrial Hygienists (ACGIH) published a threshold limit value (TLV) of 1 mg/m3 for wood dust, excluding western red cedar. The TLV for western red cedar is 0.5 mg/m3. Oak and beech wood dust have been confirmed as human carcinogens and birch, mahogany, teak, and walnut are classified as suspected human carcinogens (ACGIH, 2011).

How Risks are Reduced:

Downdraft tables are workbenches with slots or holes in the horizontal work surface. Air is drawn past the workpiece and into the slots or holes by a vacuum, which is either attached via the extraction port or built into the table, capturing dust near the point of generation. The wood dust is then collected and removed from the work environment, reducing the concentration in the worker's breathing zone and the opportunity for skin contact.

Using dust collection techniques will visibly reduce airborne particulate matter, but the extent that it reduces the small, inhalable particles is particularly significant. Although exposure is not reduced to zero, substantial reduction has been documented. This is dependent on the amount of air flow through the machine, the distance between the object creating dust and the ports on the table, how effectively the collector removes particles from the air, the nature and amount of work and the extent to which workers are exposed to particles that are not captured. While published sampling data on these specific tools are not available, evidence indicates exposure to inhalable wood dust can be significantly reduced through the use of dust extraction methods.
 
In a wood dust control study, a prototype downdraft table was built in a carpentry shop to reduce dust exposures below the Threshold Limit Values (TLV). Samples were taken during sanding activities with different types of sanders, and compared to samples when the table was not in use. Results indicated that worker exposure was reduced between 56 and 85% with the use of the downdraft table. Therefore, the downdraft table was described as an effective asset in controlling the amount of dust within the work environment (Martin, 1997).

Effects on Productivity:

Vacuum dust collectors should have a positive effect on productivity and definitely 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.  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.

Additional Considerations:

There are additional conditions and practices that can improve the performance of dust collectors and reduce dust exposure:  
 
  • Keeping your head away from dust created by the process and using adequate ventilation is key to controlling exposure to airborne dust particles.
  • The Scientific Committee on Occupational Exposure Limits (SCOEL), which was established by the European Commission, stated that exposures greater than 0.5 mg/m3 of wood dust could cause pulmonary effects and should be avoided.
  • The particles that can do the most damage in the lungs are small enough to penetrate or bypass 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.
  • 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 and coarse pre-filters are available with some vacuums and may help maintain the air flow rate.
Large electric vacuums commonly require 20 amp electrical circuits. Cords and extensions must be rated for the tool's power requirements, be inspected regularly, replaced when damaged, and used in combination with ground fault interrupt circuits.
 
Some large vacuums, cyclonic separators, and exhaust ventilation blowers can be very loud. Noise levels may be high enough to cause significant hearing loss over a work lifetime. Buy quiet devices and maintain them properly. Noise exposures can be reduced by working further away from the noise source, enclosing the noise source, or using ear plugs or muffs.

As is the case with any construction equipment, users should follow manufacturer scheduled maintenance and safety recommendations and comply with any applicable regulations.

Availability

Denray Downdraft Table
To obtain information, visit http://www.denray.com/ or contact 1-800-766-8263 sales@denray.com

JET 708403K Downdraft Table
To obtain information, visit http://www.jettools.com or contact 1-800-274-6848 customerservice.us@waltermeier.com

DualDraw Downdraft Tables
To obtain information, visit http://www.dualdraw.com or contact 1-800-977-2125 service@dualdraw.com

Air Dynamics Air Wolf Downdraft Table
To obtain information, visit https://www.airdynamics.net/ or contact 1-717-854-4050 sales@airdynamics.net

Filter 1 Downtron DFW Series
To obtain information, visit http://filter-1.com or contact 1-800-289-0189 info@filter-1.com

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.