Wet or Dry? Different Types of Dust Extraction

As fume and dust extraction specialists, it’s one thing for us to tell you that your workspace needs an at-source extraction solution to comply with COSHH standards. But which type of dust extraction do you need for which situation?

Here, we answer that question with an in-depth look at wet dust vs dry dust collection.

But first, we’ll answer a more foundational question…

What is dust and why is dust extraction important?

As we’ve previously mentioned in our blog on dust extraction, workplace dusts can come from any number of industrial processes and, depending on their size, are classified as either inhalable or respirable.

When workers breathe in these dusts, the particles come to rest in either their upper or lower respiratory tracts – potentially creating all kinds of nasty health problems like asthma, COPD, or worse.

Additionally, some dusts are combustible, meaning they pose a significant explosion or fire hazard.

Between those reasons, it’s not difficult to see why dust extraction is essential in workplaces with industrial machinery and processes. It’s no wonder that the Health and Safety Executive now dishes out fines of up to £2,000 to businesses found to use inefficient or flat-out wrong dust extraction solutions.

The different types of industrial dust collections systems explained

There are, broadly speaking, two different types of dust extractors, along with three different classes. We’ll look at the classes first before covering the individual approaches.

L Class (entry or lower level)

Specced for dusts with a MAC (maximum allowable concentration) of >1 mg/m³, L-Class extractors are mainly used to extract dusts from soft woods and some solid surface materials.

M Class (middle level)

Able to extract dusts with a MAC of ≥0.1 mg/m³, M-Class extractors are suitable for dusts from boards, brick, concrete and soft woods. They typically include additional features and controls, such as a suction rate alarm to notify users if a blockage causes a loss of suction.

H class (higher level)

Offering even greater suction levels, H-Class dust extractors deliver extraction to a MAC of <0.1 mg/m³. Typically used in environments where carcinogens are a significant risk, these also protect workers against asbestos, mould, plus even some germs and bacteria.

The different types of industrial dust collections systems explained

Now we’ve got the dust extraction classes explained, we can begin to answer the question posed at the outset of this post.

The two different dust extraction methods mentioned above are as follows:

Dry dust collection

By far the most common form of dust collection, dry dust collectors are typically cyclone or media collectors like high-efficiency cartridge collectors or baghouses.

The air separators in these units use a baffled inlet to force air through a filter media. This collects dust, which is then dislodged from the filters into a hopper or bag. Best suited to collecting heavy dusts, dry dust collectors can nonetheless be graded at any of the three classes described above.

Wet dust collection

Wet dust collectors can be cyclonic, centrifugal or venture systems. They use a combination of air pressure and water to scrub dust from the air, then drive it through a water stream or spray, leaving the dust itself to be separated by gravity and settle at the bottom of the tank.

The main benefit of this approach is a more concentrated filtration which is both more adept at capturing finer particles, and also far better at minimising the risks of explosion owing to the fluid used in the filtering process. Wet dust collectors are therefore typically specced to M or H classes, and used more selectively, mostly to manage processes involving highly combustible dusts.

So… wet or dry? What’s the best dust extractor for your workshop?

If you’re weighing up the different dust types and classes and choosing between types of dust extractors, a simple question to ask yourself is: how heavy and combustible are the dusts in my environment?

If you’re dealing with light, sticky or especially highly combustible dusts (like aluminium), a wet dust extractor could be what you need.

But if you’re dealing with medium to large-sized dust particulate that’s also less combustible (for instance, wood, flour, sugar or other food dusts), dry dust collection is likely to be both more well-suited, and more affordable.

At VODEX, we offer a range of dry dust collection systems designed specifically for individual industries and applications, as well as highly efficient wet system collectors and scrubbers designed to scrub the air for hazardous metal dusts.

Still not sure which you need – or maybe if you even need both? Get in touch, we’ll be happy to talk you through your options.

Related Reading

• Dust Extraction
• Filtered Extraction
• Different Types of Filters and How They Protect You
• How to Ensure Healthy Lungs at Work
• Wet Extraction Products for Combustible Dusts