Wet Filtration Explained

Wet filtration systems are commonly used in industry to collect reactive or combustible dust that might otherwise present a safety hazard.

Dust from metals such as aluminium, magnesium and titanium are examples of materials that require wet extraction to reduce the risks of workplace explosions and fires. Protecting employee health and safety, it ensures compliance with the Control of Substances Hazardous to Health regulations imposed by the Health and Safety Executive in the UK.

What is wet filtration?

Industries such as food and beverage production, water treatment, chemical processing, pharmaceuticals and aerospace commonly use wet filtration systems because they are more effective in purifying the air and ensuring safety.

Wet dust collectors trap particles by passing the air stream down through water. The airflow is then directed through filtration processes to trap moisture droplets, preventing them from being carried out of the dust collector.

Effectively capturing airborne contaminants that may otherwise pose a risk if not properly contained; water in the system mixes with extracted dust to form sludge, preventing the formation of a potentially hazardous dust cloud that can ignite.
An arrangement of baffles creates the vortex that acts as a particle separator. The resulting “mud” that is trapped in the tank can be safely collected and disposed of. Filtered air exits the wet dust collector, to be recirculated into the atmosphere in the work environment.

The process reduces the risk of fires and explosions in the workplace by preventing sparks from igniting. High quality wet dust collectors should have a minimum efficiency rate of 99.9% and capture particles as small as 0.5 microns, which is one-thousandth of a millimetre.
A wet filtration system is recommended when processes cause particles or sparks that have self–ignition properties, such as in metallurgical and aerospace industries.

How does wet filtration differ from dry filtration?

Choosing the type of unit that best suits your business is based on the speed at which it can contain pressure generation and prevent particle explosion. A dust collector must be able to combat the risks of an explosion. Wet filtration can extinguish the sparks faster than a dry collector, so it’s more suitable for high-risk applications.

Dry filtration systems comprise several different types of dust and particle collectors. Typically, contaminated air will enter the collector, causing the particles to fall downwards to filter them out and subsequently, the clean air will then be extracted upwards.

Relying on various types of filtration media, depending on the different conditions in which they are used, factors that influence filtration include particle size and shape, humidity, air temperature, explosiveness and electrostatic charge.

Dusts created by processes using magnesium and titanium are too reactive to be captured by a dry filtration system, as they are highly flammable and produce sparks when being worked. Only a wet dust collection system is suitable for these applications.

If the dust becomes airborne during processes such as grinding, cutting and sanding, it can remain suspended in the air, where it can ignite and explode, making it particularly hazardous to employee safety, with the potential for loss of life and destruction of property.

How do wet collectors work?

Various wet collectors are offered by AirBench to prevent the build-up of hazardous workplace dust, such as our AirBench WB wet filtered downdraught bench, which is known for its user-friendly design.

It comprises three downdraught benches in which a water spray is the primary filtration mechanism. The internal system of baffles induces a spray action using air movement to agitate water in the unit’s base. Suitable for combustible dusts, our WB wet filtered models are purpose-built for production level industrial use.

Designed to extract combustible dusts such as titanium, they feature heavy duty 2mm steel fan and filter housing; a stainless steel main body for corrosion protection; and a perforated, powder-coated, 3mm stainless steel surface. Fully welded, they feature a secondary mist filter for final water removal. They can withstand 150kg surface loading – up to 500kg surface loading available on request.

Our AirBench FP heavy duty downdraught bench is efficient at handing various materials and is particularly beneficial for use in heavy industrial applications.

The AirBench FP range comprises five downdraught benches in which the filters are accessed through the surface. FP models can be supplied with a wide range of alternative filter configurations to suit different dust and fume extraction applications. Ideally suited to customisation and modification during manufacture, they are suitable for most applications, including coping with heavy industrial use. Fully welded and powder coated, they are made from heavy-duty 2mm steel. FP systems feature a 3mm steel surface that can withstand 50kg surface loading – up to 500kg on request.

Our wet dust extraction systems offer outstanding build quality and sturdiness for a wide range of applications, ensuring the long-term health and wellbeing of workers.