Carbon filters use activated carbon to remove odours from the air.
Activated carbon is heated to a very high temperature, which drives any chemicals out of the carbon and leaves only pure carbon behind. Like a sponge, activated carbon readily adsorbs chemicals, smells and moisture, removing any unwanted odours from your grow environment.
Are there different types of carbon?
There are two types of activated carbon: granular and pelletised. Less adsorbent than granular carbon, the pelletised version is formed when activated carbon dust sticks together to form pellets. Granular carbon is carefully sieved and graded in the form it came out of the furnace. It has active adsorbent sites throughout its structure, making it 5 times more effective than its pelletised counterpart.
All Global Air Supplies filters utilise the more effective granular carbon.
How carbon filters work
Housed in a steel mesh body, the carbon is vibrated down to create a uniform layer inside the body. A pre-filter is usually wrapped around the outside of the filter to protect it from dust and solid particles that could block the filter.
Air is then pulled through the filter by a duct fan, and as it travels through, any chemicals are adsorbed by the carbon. The air travels so fast that it traps chemicals as it passes through.
VOC’s (Volatile Organic Compounds) are released from plants that give odour. Carbon filters are extremely effective and stop 99.9% of odours from travelling through the filter.
The performance of a carbon filter can be affected by the volume of chemicals entering the filter, such as smoke with very high concentrations of chemicals and dust. The other main cause of failure is moisture. High humidity can saturate the carbon, filling in pours in the sponge-like structure and allowing odours to bypass the carbon. Perfecting your environment is crucial to prevent extreme conditions hindering the effectiveness of your filter.
Choosing a filter
The size of the filter governs the maximum air flow – the flange size should always be matched to the size of the fan. All carbon filters reduce the maximum air flow through a fan, meaning carbon filters are normally the largest restriction to air flow in a ventilation system. When you have calculated the air flow you need, select a fan and filter combination that can move that volume of air.