Activated Carbon Filter

How active carbon is made.

Most active carbon, as used for gas or vapor trapping, is made from coconut shell. The shells are heated to over 2,000°C under high pressure, which causes fissures on the surface of the carbon, creating a high quality, small pore activated carbon. The fissure system is extensive, creating a very large surface area in a small package, and it is in these fissures that other gases and particles are trapped. A single greenscreen activated carbon filter has a flattened surface area of a football field.

How active carbon works.

Activated carbon absorbs gases and particles by a combination of London Force and small electrostatic forces that creates a type of capillary action. In layman’s terms, activated carbon acts much like a sponge absorbing water, except that the carbon absorbs the materials at a micro level.

Active carbon’s holding power.

Activated carbon holds onto the material it has absorbs quite well. There is no risk in the environment of usage that an active carbon filter will give up or "desorb" the material it has captured. Active carbon will only desorb the captured materials starting at 600°C through 2,000°C and under high pressure. For this reason, all greenscreen Air Filter Masks feature replaceable filters. The filters cannot be cleaned or re-used once fully absorbed. Fortunately, the materials used in our filters are biodegradable and environmentally friendly.

How long does a filter last?

This is a question that is difficult if not impossible to answer. Active carbon by nature loves to bond with anything and everything. Longevity depends on the degree of saturation and environment that the mask is used in. The saturation level is not unlimited. For example: Using a Greenscreen mask while commuting on a bicycle in Los Angeles California will be different than commuting in Dubuque Iowa. In general heavy urban traffic will saturate the carbon after about 20-30 hours of use. Lighter commutes you can expect 30-50 hours of use. Use in a well-ventilated garage while doing arts and crafts type of activities will result in 15-20 hours of use. In the same garage without ventilation and the filter is toast in 20 minutes because of the heavy environment it is used in. Additionally there is no indicator to warn the user when the filter is saturated. You will need to keep track of this on your own. In general the filter will keep out the bad smell of a pollutant for nearly 10-15 hours after the active carbon has been saturated. In short if you are using a mask for protection against air-pollutants that can physically harm you like: Paint Thinner, Car Exhaust etc... you will be breathing in unfiltered air for 10-15 hours even it you do not smell it. Unfortunately trial and error is the best method of determining the exact life of a filter given your specific application and environment. No matter what the situation a filter should be considered saturated after 60 hours of use.

NOTE: When you are not using the mask you must keep the filter in a air tight zip-lock bag. The carbon is always active and will filter anything it comes in contact with. As we have no control over this situation MFI is not responsible for any use or misuse of its' products.

MFI 563 Via San Miguel Lane Liberty, KY. 42539 Tel: 606-787-0022 FAX: 606-787-0059 e-mail: mfrost@mfiap.com

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