What do the different filter ratings mean? HEPA, MERV, 95%…?

Filters are rated on their efficiency to stop and trap particulate of a particular size. Most filters used in Ace extractors base their efficiency rating on stopping particulate of 5 microns or greater. A micron is 1/25,400th of an inch in diameter, and most carbon steel welding particulate is approximately 5% microns in size. So an Ace 95% filter will stop and trap 95% of particulate 5 microns or greater in size, effectively stopping most carbon steel welding particulate while still achieving high airflow performance.

Ace HEPA filters, on the other hand, stop and trap 99.97% of particulate .3 micron in size or greater. This filter is particularly effective is capturing Hexavalent Chromium in stainless steel welding processes, because chromium particulate is much smaller in size than carbon steel welding particulate.

In addition to above efficiency ratings, Ace now shows an equivalent MERV rating on many of its product literature and on this website.  MERV, which is an acronym for Minimum Efficiency Reporting Value, is a rating devloped for use by the HVAC industry.  However, in recent years some of Ace’s competitors have used the MERV system to represent their filter ratings, so to facilitate the process of fair comparison between Ace’s and competitors’ products, we now provide our filters’ MERV ratings along with our standard efficiency ratings.

The MERV rating system assigns a number between 1 and 20 to filters of varying efficincies, 1 being the least efficient with 20 being the most efficient.  The most common Ace filters are listed in the chart that follows (click on link), along with their corresponding efficiency and MERV ratings.  Use this guide to determine the correct filter for use in your work application, but when in doubt, please contact your Ace representative or the factory.



Why should I use a fume extractor instead of wearing a respirator?

The short answer is that a respirator protects the welder wearing it, but does nothing for nearby workers not wearing similar protection.

The somewhat longer answer is that a repirator, as good as they are in protecting the person wearing one, does not capture and contain weld fumes in the general atmosphere.  As such, other workers in the area could potentially be exposed to high levels of hazardous welding fume particulate.  A fume extractor can mitigate that risk because it captures fumes from the local area of welding, which is why fume extractors are often referred to by the the term Local Exhaust Ventilation.

In critical work applications, or wear hazardous exposure levels are high, repsirators AND fume extractors may be employed in combination with each other.  Your safety manager and/or an industrial hygienist can advise you on best practices for the reduction of exposure to hazardous welding fumes.


How do I know which extractor to choose?

There are several factors that determine the best extractor to use, including location, usage, materials, and quantity of smoke/fume produced. In general, however, the rule of thumb is this: Portable extractors are the best choice for jobsite work, maintenance welding, and production benchwork. Mobile extractors and downdraft tables are best suited for continuous production welding processes. Stationary extractors are also best suited for continuous production processes where floorspace limitations prohibit the use of mobile extractors and downdraft tables.

Aren’t used filters considered Hazardous Materials?

There are currently no “blanket” regulations prohibiting the placement of used filters into standard trash receptacles. Local authorities, however, may place certain restrictions on this procedure, so we advise checking with applicable agencies to ensure conformance with regulations

Why should I use a fume extractor instead of an ambient (overhead) air cleaner?

Ambient air cleaners are effective supplements to fume extractors, but should be avoided as a primary tool for fume control. Because of the nature of how ambient air cleaners work, fumes must first pass by a welder’s breathing zone before drifting into the capture zone of the ambient unit. As such, the welder is exposed to as much dangerous welding fumes as if he or she had no extraction equipment at all. As stated, it is best to use ambient air cleaners to support source capture fume extractors and to provide general air cleaning and circulation.

How close should my fume extractor’s hood be to the welding arc?

Welding fume extraction hoods should be placed close enough to the welding arc to be effective, yet not so close as to distrub shielding gases or obstruct the welders line of vision.  We call the optimal distance from the arc the sweet spot, and the sweet spot is determined by placing the edge of the extractor hood approximately the length or diameter of the hood from the arc source.

For example, when using Ace portable extractors, which employ 10 inch hoods, the sweet spot would be approximately 10 inches from the arc source.  Slight adjustments may be needed, but 10 inches should be a good and effective starting point.

To mitigate the possibility of any vision obstruction, Ace fume extraction hoods are designed to be effective when placed at about a 45 degree angle relative to the welding surface.  Positioned in this manner, the hood pulls fumes from the top and the side of the arc while being angles away from the welder.  The following photo demonstrates the proper hood position that is both effective and unobtrusive.



How do I know which filters to use in my extractor?

Ace makes a wide variety of filters available that work in combination to provide the best possible filtration for your work application. Generally speaking, 95% main filters and standard pre-filters provide effective filtration for the vast majority of welding operations. HEPA main filters can be used in place of a 95% filter to provide additional protection against toxic particulate such as Hexavalent Chromium. Specialty pre filters may be used to help abate smoke odors and oil mist. Your Ace dealer can you help determine the best combination of filters for your application.

How long do filters last?

There is no clear answer to this question as too many factors can influence the life of filters, including, but not limited to, welding process, type of materials, condition of materials, run times, position of extraction hood relative to the arc, welder skill level, ambient air movement, humidity, and more. Filter status indicators are included on all portable, mobile, and downdraft tables to help the operator determine the filter lives for their unique welding conditions.

Why should I use a fume extractor instead of placing fans in my shop to blow the fumes away from my welders?

The practice of using fans and blowers in this manner is called the dilution method, and while it is commonly used, this method may not be effective in removing weld fumes in any except the smallest of shops. Disadvantages include lack of uniformity in diluting the fumes throughout the shop, downstream concentration of fumes as they are blown away from the fan, temperature variations throughout the shop, inability to actually decease overall exposure levels of hazardous welding particulate, among others.

How do I dispose of used filters?

Used filters can be easily removed from Ace extractors. We recommend the operator wearing gloves and protective eyewear, placing the removed filters into a trashbag, sealing the bag, and placing the bag in a trash receptacle.

5043 Farlin Ave.
St. Louis, MO 63115

800-949-1472 (US)
314-385-5178 (Outside US)

Connect With Us