Letter Re: Do-It Yourself HEPA Air Filtration for NBC Shelters

Friends,
In the wake of the Japanese nuclear plant melt-down situation, I called a safe room manufacturer for a hand cranked air filter.  It was over $2,000.  Too much.  I did learn that you need both particulate (HEPA) and gas (carbon) filters.   I have jury-rigged an NBC air filtration system.  Here it is:

Go to a hydroponics store or find one online.  Yes, the one’s that people go to in order to grow marijuana. You will need an inline fan.  I used a  continentalfan.com AXC150B-C fan.  It is a little more expensive but German engineering costs more.  (Quieter too). You will need a carbon filter.  I used a Can-33 activated carbon filter (made in Canada) You will need a 6 inch Greenhouse HEPA filter.  It can be washed and reused but only put it back in your system if it is completely dry.

Total cost about $450.

The HEPA filter is attached to the air intake of the fan. The Carbon filter is attached to the air exhaust of the fan.

This is a recirculating system, not an overpressure system. At 300 CFM, it will clear the air of a 10’x10’x10′ room in 3 minutes and 20 seconds.

It stands completed at 30″ high and 16″ wide at it’s widest point. It uses 130 watts of current. – SF in Hawaii

JWR Replies: A HEPA filter system with air pushed by an electric fan is best suited to someone that has a fairly capable alternative energy system. Anyone without a large power source that can be relied upon for weeks should substitute a hand-cranked fan. And even those that do have a large alternative energy system should always have a “Plan B”: An electric filtered ventilation system should have a hand-cranked or pedal-cranked backup. There are too many potential points of failure to entrust our lives to continuity of electric power.




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