Updated emergency nuclear contamination filter element - making it more versatile.

I changed the filter element to be able to fit in a standard 5 gallon bucket and make it easier to change out. I think this way will make building and storage better.

[@101perspective]

Shouldn't it go through the filter before it goes through the carbon? Shouldn't the order be: 1) Batting 2) Filter 3) Carbon 4) Small amount of Batting (in case some carbon gets loose) Also, do you know if this is enough carbon to actually stop anything? And if so, how long do you suspect this amount of carbon would be good for? I know the professional systems use like 30+ pounds of carbon. However, they are also designed to last for months which seems a bit overkill.

[@edwardjackson9791]

The batting (roughing filter) on the inlet is good and helpful to prevent plugging. The reason for the carbon first is it captures radioactive gases and holds them up for a long period. The gases pass through any filter. The carbon traps the gases and allows them to decay into fission particles which the filter can then remove. As for amount of carbon, the beds at nuclear plants for the control room were 2 inches deep beds. But the important part is the air flow through the activated charcoal should allow at least .25 seconds of contact time so you want a flow rate that allows that contact time. In reality you probably don’t not a lot of air flow. I have a CO2 monitor to make sure there is enough makeup flow. The activated charcoal will probably last a very long time so the limiting part will likely be the HEPA filter. But this system would likely be good for over a month and if you are just using for makeup flow it would likely last much longer. For the cost you could make spares that you could exchange if needed. Hope this helps. Thanks for the questions.

[@alandolan2182]

Something that might help in first going through a water filter then charcoal filter then air filter. Just a thought water works wonders on lots of stuff as does activated charcoal to remove dust and toxins in the air.

[@edwardjackson9791]

Water would help some but not as much as you may think. The radioactive gases will not be held up by the water much because they are gases. The contaminated particles will be refused some but when you have to draw the air through the water you get a lot of head loss and will have to compensate with a more powerful fan/blower. So, is the slight added filtering of the water worth the extra power needed and complexity? That you will have to determine but nuclear plants don’t use water as a filter aid except for very specific emergency conditions and the only to help slightly.

[@SlappySlapperman]

If you fart in a bathtub, it still stinks.....😉

[@ewaddington1]

I’m actually building a similar system right now because I can’t afford 8800 for a store bought one. I have a question for you. This filter helps to pressurize the room/enclosure you will be in, how are you addressing the air outflow?

[@edwardjackson9791]

Unless you have a really tight shelter it will naturally leak out. If it is tight you can put a damper in to allow air to escape like a dryer vent.

[@guytech7310]

You need to get the airflow leakage low to keep an area over pressured. The more leaks the more difficult it will me to maintain a positive pressure. You could seal a much smaller space than an entire home such as a room or two. If you have a real tight shelter than you can use a exhaust port, this could be simple as a small PVC pipe vent with an unglued PVC cap that you can remove. You can make use another PVC end cap with some holes drilled in so you can tune the positive air pressure in your shelter. FWIW: I recommend a much bigger carbon filter. Perhaps a entire 5 gallon Pail filled with charcoal or activated carbon. For my design I am using a box made of plywood so I can fit multiple HVAC filters and a large container filled with activated carbon, and using 3" PVC for air intake.

[@ewaddington1]

@@guytech7310 I’m using an above ground tornado shelter in my garage that I am going to fortify with sandbags. Using thick plastic sheeting I hope to make a sort of tent that can be pressurized. Fingers crossed

[@guytech7310]

@@ewaddington1 I don't know if you have adequate shielding in a above ground shelter. You need at least 12" of mass on all sides presuming your distance from any targets and not downwind. For the first few hours it could be as high as 1000 Rad/hr. Humans can only tolerated about 100 Rads in a short period before getting acute radiation poisoning. 4 inches of concrete will reduce rad exposure in half, 12" will reduce to about 1/8. with an outside of 1000 Rad/hr, with 12" of shielding would cause a 125 Rad dose. Ideally fallout shelters need 24" of concrete or 36" of soil to provide adequate shielding in the worse case. You might be able to get away with less if you are distant from any targets or nuclear power plants which will likely meltdown in a nuclear war. Also need to be away from any airports as those are likely ground strike targets. Below ground shelters are just easier to work with since you got natural shielding on all sides except for the ceiling.

[@ewaddington1]

@@guytech7310 sadly it’s the best I can do at this point. Steel and several layers of sandbag is all I have. Dropping a bunker in is cost prohibitive for me. 40000$ is what I was quoted and that’s a no go. Any suggestions?