Pioneering Hydroponics

Since 1976

Carbon Facts

Whats the difference between the different types of carbon?

There are 3 types of carbon used for air filtration; Pelletized, Coconut and Granulated.

Pelletized carbon is produced by burning coal and processing it into tiny rods. These are then broken up and distributed through the filter. This method is probably the worst carbon to use in air filtration. The process of creating the pelletized carbon involves the carbon being crushed into pencil like structures then bonding agents are added to hold the pellet together, this collapses the pores structure which in turn makes the carbon less affective as the organic microbes cannot be absorbed by the carbon. Because of the small pore size of the palletized carbon it will only be re-activated to about 50% or less which in turn affects the absorption rate. Also pelletized carbon contains a large percentage of ash.

Coconut carbon is produced by burning coconut fibres. This produces carbon with a greater surface area than coal but with much higher ash content and higher moisture levels. Ash is a "dead" material within the carbon and offers no benefit to the user, coconut carbon carries around 20% ash with a 5% moisture level, this high moisture level detracts from the overall adsorption of the filter. This carbon only has about a 12 month life span and is very ineffective.

Most granulated carbon is produced by burning coal that is left unprocessed giving you the virgin granulated carbon used in Rhino Filters. This carbon has very low ash content less than 13%. The carbon is almost magnetic to the organic compounds in air (odours).

How is carbon produced?

By burning a source material, usually coal; the remaining material after burning is carbon. The carbon is burnt in a kiln at a very high temperature, but with very low oxygen content and a high moisture level.

What makes carbon good for air filtration?

Activated carbon is great for extracting organic compounds from the air. Carbon is porous and is constructed of many pores, the bigger the pore size the better the carbon will work. The pore size of RC412 is 0.02 micron which doesn't sound a lot but in the carbon world it is massive. This makes the carbon very absorbable to organic compounds and attarcts these carbon particles like a magnet. The carbon is positively charged which attracts the negatively charged ions in the organic compound (i.e. smells and gases). The organic compound basically sticks to the outer edge of the carbon and then because of the pourous structure, it absorbs into the centre and locks it there.

What is activated carbon?

Carbon is activated by burning it in an oxygen-depleting atmosphere. Similar to how wood smoulders in a stove when only a small amount of oxygen is present. In a kiln it is similar, but there is much less oxygen and the temperatures are much higher. When the carbon is exposed to these high temperatures in the presence of little oxygen and with excess steam, microscopic pores open up within the carbon. This creates a greater surface area and "charges" the carbon with positive electrons.

Pelletized carbon can be re-activated but its efficiency drops to under 50%, Some carbon contains more impurities than others and once burnt still remains unusable for air filtration because the pour size is so small. RC412 burns at such a high temperature that when it is subjected to very low oxygen levels and activated by steam it opens the pores of the carbon and positively charges the carbon.

What importance does pore size have on carbon?

Pore size is very important as the bigger the pore size, the easier it is for the carbon to absorb organic compounds. RC412 has a pore size of 0.02mm which is large in the carbon world. Anything under this will affect the absorption rate of the odour.

What is ash content?

Ash content is the amount of "dead" material left when carbon is produced. All carbon contains some ash but as it's an inactive substance, less is better than more. Coconut for example can contain up to 20% ash, meaning it can only ever be 80% effective. Our carbon – RC412 – contains only 13% ash.

What about carbon purity?

Rhino filters offer one of the highest fixed carbon contents per gram of any carbon on the market with up to 90% pure carbon in every gram. 

What is contact time?

Contact time is a measure of how long contaminated air needs to be in contact with the carbon for total removal of impurities. At an estimated 0.05 seconds, our carbon has one of the shortest contact times of any carbon available.