Dear Table 1, I know you’re there to help protect the health of concrete workers around the country, but you’re awfully confusing at times. Just tell me when you need a HEPA filter for Table 1 compliance already!
I imagine this is how just one of many letters we’d like to write to OSHA Table 1 might start – and it’s probably a little more civilized than some of us would like to be. Still, OHSA’s updated silica dust regulations went into effect on September 23, 2017, and the industry is still adapting.
One area that’s a major headache is what a dust extractor actually requires. Three major components come into play – CFM, filter cleaning, and HEPA filters.
A Quick Table 1 Dust Extractor Overview
First of all, we need to clarify that Table 1 covers most, but not all applications that create silica dust. For those applications not covered in Table 1, you also have Objective Data and monitoring options available. If you’re a Bosch customer, you check out their dedicated compliance website to see how their products line up.
Table 1 is clear when you need a dust extractor with a filter cleaning mechanism. Another point to clarify is this term “filter cleaning mechanism.” It doesn’t have to be automatic like most dust extractors have – though that feature is nice. It can be a manual cleaning system like we see on many onboard rotary hammer extractors. The goal is simply to be able to clean the filter without reintroducing the silica dust you collected back into the air. However, some applications allow for just a cyclonic pre-filter system and not a cleaning mechanism.
For CFM, the easy equation is that you need 25 CFM for every 1″ of grinder wheel you’re using. A 5″ grinder needs 125 CFM of dust extraction – 5″ x 25 CFM = 125. Simple.
In most Table 1 applications, the filter requirement is that it “has a filter with 99% or greater efficiency…” Guess what – that’s not a HEPA filter. HEPA filters collect 99.97% of all particles 0.3 microns or larger which exceeds the minimum requirement. While you need to check to be sure, most dust extractors come with a filter that already meets the 99% requirement.
When You Need a HEPA Filter for Table 1 Compliance
Table 1 requires a HEPA filter for two types of applications only. Hole cleaning and surface prep with grinders or walk-behind machines. That’s it. Here are the applications as stated in Table 1:
- (vii) Handheld and stand-mounted drill (including impact and rotary hammer drills) – HEPA filter is required for hole cleaning only
- (viii) Dowel drilling rigs for concrete – HEPA filter is required for hole cleaning only
- (xiii) Walk-behind milling machines and floor grinders – HEPA filter required for indoor or enclosed space use if you’re not using a water delivery system for dust control
And that’s it – just three mentions in all of Table 1 and two types of applications.
But There’s a Way to Stay in Compliance and Use HEPA Filters Even Less
For the two hole cleaning HEPA applications, there a way to do it without using a HEPA filter. When you’re using an ICC-approved chemical installation method for anchors, using a hollow core drill bit like the Bosch SpeedClean eliminates the need for a HEPA filter. You’re extracting the dust at the point of creation so you don’t have to blow the hole out.
You can still use a HEPA filter in all applications. It meets the requirements of 99% efficiency or better. You just don’t have to for most applications. Realistically, you’re better off not using them when you don’t have to. There is a performance drop that comes with using a HEPA filter and they’re more expensive.
To find out more information on when you need a HEPA filter for Table 1 compliance, check out Bosch’s website.