Doc,

It's a good read - second time someone has posted that link in the last few days. Oak Ridge did other important R&D during the cold war that is also applicable to today. I've refrained from participating in the plastic-and-tape rock throwing so far because I already decided that it was ill-informed crap. Having previously been in charge of about 80 senior scientists and engineers, I know that people are people (strong opinions) about all sorts of things, but only real research (like the Oakridge folks did) yields useful information.

Someone recently suggested one of Dean Ing's books, "Pulling Through". Ing's book is fiction, sure, but setting any politics or PC stuff aside, it is mostly based on good science. But the other half of the book by Kearny and associates isn't even remotely fiction - it is solid, hard-earned, factual information. Most of that is 'N/A" to the present concerns; some of it is VERY applicable. I've read - have in my library - other "hard-science" publications from the Oakridge boys and similar outfits, and there is useful information in them as well, even though the focus is on other situations. (Yeah, I've made a couple of KFMs - years ago - and they WORK - far more accurate/useful than any readily available geiger counter, and that is truth that I personally verified with calibrated emmiters. Ing's fiction accurately depicts some of the "things to watch out for" when making/using a KFM... hmmmm... maybe other things in that fiction are things to consider as well, such as ventilation... food for thought...)

In Bill's defense - I've been up close to that Mayor in a crisis (not that he even noticed me at the time), and he is a tough, effective mayor when the chips are down. Sure, he and the Chief are politicians <shrug> I personally do not like his politics, but give him his due - he made some pretty good decisions in a past crisis and probably will in the future if circumstances call for it. Also... winter storms are a reality in the windy city, and the hot topic a few days ago was supposedly aimed at the East coast, not Chicago - I can sort of understand his sneer, even tho I disagree with his "dissing" the advice of the other agencies - thus tossing the baby out with the bath water.

In my opinion, Daly is the kind of mayor who would readily order the explosive demolition of buildings with people potentially in them to save many other people and buildings... very ruthless. I do not admire him, but he is not taken lightly. Too bad he didn't explain his disdain for the advice...

On a lighter matter - gee, the combination of poly sheeting and duct tape is soooo adaptable to so many uses, why would anyone NOT have it on hand? Sheesh, it's kind of fun to play around with! FWIW, I greatly prefer 4 mil poly for general use and 6 mil for rugged use. After that, it gets too darned expensive and even 6 mil is pretty heavy, weight-wise. And don't just get a roll of "clear" - the black has other uses, and the two together have many more. As for duct tape - caveat emptor. 3M stuff sets the standard. The discount stores carry a lot of crap duct tape. I have occassionally found Chinese-made duct tape at an incredible bargain price that is fully the equal of 3M in adhesion and coating, but it pays to examine the tape before buying. There are some other North American-made duct tapes that are the equal of 3M, but I don't recognize the brand names - it's possible that they are re-branded 3M, anyway.

Anyone else ever made a boat that safely carried three people across a large body of water with cardboard, limbs, visqueen, and duct tape? Like I said in a previous post, the MacGiver character would have a brain lock-up with the possibile uses of poly sheeting and duct tape, hehehe...

Regards,

Tom
"Minds are like parachutes... they both work best when open..."

What would be a good way to pressurize & filter the air in a safe room?

The Oak Ridge National Laboratory's study establishes that an expedient, sealed safe room provides substantial protection from an attack with nerve gas. Positively pressurizing the room increases the protection by insuring against leaks in the room. So the next issues are what can we use to pressurize the room; and what can we use to filter the air introduced into the room.

An electrical air pump appears indicated. AC power would be low maintenance, but by itself does not seem secure enough for me to trust my family's lives on it. A DC source, probably from battery seems essential.

A bathroom exhaust fan in, say, vent piping might provide an AC air pump. Some have recommended battery-powered air pumps such those made by Coleman to inflate air mattresses being attached to gas mask filters to provide pressurized, filtered air for a safe room. However I really wonder about the reliability of those pumps, especially for prolonged use. Gas mask filters are designed for a much lower volume of air than would be produced by a continuous flow from an electric pump. Also I believe that their reliable life is limited to a few hours even when they filter only the breathing of one person. A filter with a longer useful life and capable of filtering a larger volume of air seems necessary.

Hence the quest for a more reliable air pump and a higher capacity, longer-lived filter.

Does anyone have any good ideas?

Thanks,

John

Check the "Alpha Disaster Contingency" website. I can provide you with a URL after I get to the office. They discuss the creathion of a safe room with a powered filtration system. I am not convinced of the need for that.

Nerve agent is a mist. If deployed in the open, it will simply evaporate in time. Unfortunately, there is no meaningful alert or warning system that would tell us to take shelter in an emergency. Sheltering in a safe room would not be useful in protecting us against a biological attack. IMHO, if I lived in Israel or another middle eastern country, I would establish a positive pressure safe room. A scud attack would be a reason to shelter.

I can envision no similar situation in the US.

Regards

I believe in order to create a positive pressure room; one must obtain the air from somewhere (outside air, another room, etc.). If one is concerned about chem/bio agents, the incoming air to create a positive pressure room must also be addressed with the appropriate filtration of that incoming air. Pete

For limited times a positive pressure room may be created using compressed air that was stored prior to the threat. This is only workable for very small, very well sealed rooms as the amount of compressed air and the cost of storing it becomes unacceptable quickly. But if you happen to have a large pneumatic tool shop attached to your house you might be able to use that air to pressurize a well sealed closet for a day or so. Don't know the actual math to determine what size a tank would be need for what size of room with what rate of leakage, but I think that there are people on the forum who can guess at or know the correct math or links to such.

Heads up to those that consider using regular air compressors.

As a general rule, air compressors that are used for "shop air tools" and paint booths, tire filing etc. DO NOT HAVE BREATHING AIR FILTRATION installed. A big problem with this type of comperssed air is that oil from the compressor will be present in the output air...guess what happens when lungs inhale oil? Sounds like a way to develop breathing problems.

Not trying to rain on the parade here, just want to keep folks from turning blue. There are filtration systems that can be used, search WWGraingers, McMaster Carr and other similar types of industrial equipment suppliers.

Also note that most houses have many sources of air leaks in the rooms that are not immediately obvious, such as the electrical outlets, plumbing standpipes, cracks in the floor / walls / ceiling from the building settling as it ages....sadly the list goes on.

Pressurizing from a bathroom exhaust fan is also problematic due to the looseness of the fan housing construction, need for reliable power source, having to re-arrange the ducting for the fan as most are designed to exhaust a room, not pressurize it, and the fact that many household fans may are only capable of less generating than 100 cubic feet per minute of air volume, usually at very low pressures.

Compressed air tanks (scuba etc.) generally hold less than 200 cubic feet of compressed air, which as noted earlier becomes prohibitive in terms of $ and equipment.

Regards,
Comanche7

Try the following urls

http://www.americansaferoom.com/

and several of the links on this site

http://www.alpharubicon.com/basicnbc/basicnbc.htm

Interesting idea. It's not a bad concept, but there are some logistics to consider (it's not impossible to do this if one is "inventive").

As noted earlier, most home shop compressors use an oil-filled crankcase and even when they are new, there is oil in the compressed air... but let's assume that one has an oil-less home shop compressor (it just so happens that mine is oil-less, with a 60 gallon tank). While most home-shop compressors have a 20 gallon tank, let's assume that like me, you have a 60 gallon tank.

These figures are off the top of my head, so check my numbers: A US fluid gallon is defined as 231 cubic inches. So a 60 gallon tank is close enough to 8 cubic feet. My compressor, like most single stage home compressors, shuts off at 120 psi. Disregarding any post-compression cycle pressure drop from the gas temperature dropping (ideal case), no leak down, perfect gas, etc, and assuming we start at 14.7 psi, we would stuff a total of about 65.3 cubic feet of air in the tank. Assuming we're breathing it at very close to 14.7 psi, and assuming we tried very hard to suck all the air out with a regulator/respirator, we could get about 65.3 - 8 = 57.3 cubic feet of air out of that 60 gallon tank. (someone should check my math, but that sounds about right - one order of magnitude increase in pressure will give us one order of magnitude increase in mass given a constant volume and temperature) (Sorry; I'm too lazy right now to convert all this to SI units - ask if you need it converted and I will)

SCUBA guys, how long will that last at the surface (14.7 psi to keep the numbers consistent)? I can figure out a guess from 95th percentile respiration rate and volume, but you divers can prol tell us real quickly.

But note that I mentioned a respirator - you have to cycle all 57 cubic feet thru your lungs to get whatever duration (I'm guessing less than an hour). If you simply vent it into the closet, you will have to waste air - or your closet becomes a pressure tank. Also, there is the CO2 and transpired/respired H2O vapor problem...

We can make an improvised scrubber for the CO2 and we can deal with most of the H2O vapor in a similar fashion, so it's not impossible... also, we can easily make up a reliable (gravity is reliable) and accurate waste valve for the closet to keep a small positive pressure on (only a few inches of water column is plenty of positive pressure - 1/2 psi would probably be over kill and probably be hard on the average house construction). Forget the H2O vapor build up - let it get a little clammy in there (or icy, if it's sub freezing) for awhile - but breath thru a regulated respirator that wastes into the sealed closet and let the closet waste valve maintain the small over pressure.

Choosing my words carefully... the "commercial" systems rely on filtration and blowers and waste gates to provide fresh air (it requires a lot for circulated air - CO2, H2O, 3 days on pork and beans, etc...). Even a small room is onerous to handle with a manual blower, so power becomes required rather quickly. And... there are chemical weapons that destroy the filters - first attack, OK - second attack, best have changed filters...

I am very uncertain about bio agents and filters, but I assume that is primarily a particle size issue. Start with an off-the-shelf HEPA filter and go from there... and radioactive fallout *is* a particle size problem that is not very difficult to deal with over a moderate amount of time (days to weeks).

Pre-stored clean air is the surest method. Safely storing enough of it for ______ (you fill in the blank) and being able to effectively use it is probably not as simple as sucking on the end of an airline (the *blue* air hose in my house - blue for clean air and yellow for oiled air for air tools and yes, it's manifolded and valved up to be either-or with no back-siphonage of oiled air...).

Heck, it's an interesting proposition! But I'm not going any farther with it - risk management; I'm not dumping the effort into that. If I lived someplace with higher risks, sure, I'd compare it to other solutions - 120 psi is low and I can think of a number of inexpensive large volume storage methods.

Whew! And I was trying to be finished with thinking for the day... dang!

Regards,

Tom

Doc,

Interesting reading... I learned some things! Thanks for the links.

Regards,

Tom

As Beach Doc mentioned,

This guy seems to have his stuff together.

http://www.alpharubicon.com/basicnbc/saferoomswhatsworking.htm

http://www.alpharubicon.com/basicnbc/saferoomtest2-nov-02.htm

Mike