Dr. Dan and the Baghouse

Dan was my best friend and favorite coworker for several years in the 1990’s. We ate lunch together three or four times a week. I sometimes called him Dr. Dan, and for some reason he often called me Main Man.

Dan has a Ph. D. in Geography. He was once a Professor at Columbia University. He is from Long Island, and he is from a family of commercial fishermen. His brothers are commercial fishermen. Dan is the first person in his family ever to get a college degree. He was also the first person in our company to become a Certified Industrial Hygienist, no small feat. Dan is a really smart guy, and he is kind of professorial in his demeanor, if you know what I mean.

Dan got a job assignment that pertained to a lead foundry in Mexico. The foundry baghouse had burned down, and Dan was involved because of the resulting lead contamination. Environmental work was what Dan mostly did. He came to me wanting to know all about baghouses.

I explained that a baghouse was a contraption that cleaned the air by capturing airborne particulates such as coal dust, lead dust, or sawdust. It is essentially a container of giant tube socks, or bags, which are hanging upside down; that is to say, hanging with the open ends at the bottom. Some baghouses are shaped like vertical cylinders; others are box-like. Airborne emissions that contain particulates are blown upward through the socks. The socks catch the particulates but let the air escape through to the atmosphere. In fact, the only way the air can escape to the atmosphere is through the socks.

Every so often a motor turns on and shakes the socks to knock the particulates loose, by rotating a cam geared to the sock assembly. Alternatively, a sudden puff of air is blown through the socks in the downward direction. The loosened particulates fall to the bottom of the baghouse. They are physically removed from there and disposed of. Baghouses are used in places like foundries, lumber mills, water treatment plants, and etcetera. We found pictures, diagrams, and illustrations of baghouses, but Dan wanted to see one up close in person.

Well, I knew of a place with a baghouse. My father-in-law, a very smart man called L. W., owned a lumber yard. Indeed, he had founded it and nurtured it and grown it into a very successful operation over the years. I asked him, could we please come out and see his baghouse? Of course, we could. When we got out there, we saw that it was of the cylinder variety. We discovered that the door to get inside of it was on the cylinder wall about thirty feet up. It was accessible from a little platform that you could get to by a ladder welded onto the outer wall of the cylinder. The bottom rung of the ladder, however, was about fifteen feet up. That was no problem for L.W.. He got one of his employees to bring over a fork lift, and I stood on a pallet lifted by the tongs. When I was up high enough to get on the ladder, I started climbing. Eventually I got to the door. I tried to turn the knob one way and then the other, to no avail, and I shook it and rattled it and did all the things you do with a door knob before you conclude that it is really locked. Well, it was really locked, and while L.W. was trying to remember where the key to it was, a swarm of angry wasps came after me from their nest under the guardrail.

I never descended a ladder so fast in my life, but I got stung nonetheless, a couple of times at least. Dan and L.W. were laughing too hard to be of any help. Finally, I managed to find a smoker on the premises, and I bummed a couple of cigarettes from him. I got the tobacco out of the cigarette papers and spit on it and applied the moistened tobacco to the places where I had been stung. After a little while the hurting began to subside, because, you know, the tobacco leaches the poison out. The wasp incident pretty much ended our day. Dan did not get to see inside the baghouse, and that was a big disappointment.

A few months passed. One Saturday morning I got a telephone call at home. It was Dan. He was in Sulphur, Louisiana, at a water treatment plant there. The plant used quicklime in the treatment process. The quicklime was stored in dry form, as a very fine, white powder, or dust. It turns out that while the plant’s quicklime storage tank was being refilled, there was an explosion. The roof of the tank was blown out and peeled back just like the lid on a can of peas when you open it. Quicklime was blown all over the neighborhood, up to a mile away. Dan said it looked like there had been a snow storm. Dan had been called in to assess the environmental damage and devise a remediation plan. After he got there, though, the plant manager asked him if he would also be able to determine the cause of the explosion. Dan said, oh no, sir, that he didn’t do anything at all like that. Dan told him that he would need to get me over there to figure that out.

I drove over to Sulphur, and when I got there, I had never seen anything like it. Everything was white! The quicklime tank was elevated maybe twenty feet off the ground and had a funnel-shaped bottom draw-off. The quicklime supply man stated that he had hooked the loose end of his truck hose into the tank bottom draw-off and turned on his blower. That’s how they refilled their quicklime tanks; they blew the quicklime in from the supply trucks. They had been doing it this way for years.

I always do a lot of walking around and looking when I investigate explosions. And I do a lot of thinking about how the process works. Now, it goes without saying that if you fill a tank with dry quicklime by blowing it into the tank, you have to let the air escape or you’ll blow the roof off. Which is what happened here. Therefore, the tank venting system had to have been blocked, and the air couldn’t escape. It also goes without saying that you can’t just let the air blow through the tank without capturing the quicklime, or you’ll just wind up blowing all the quicklime from the supply truck into the atmosphere. And what do you need to capture the quicklime? Yes, a baghouse. I reasoned that there had to have been a baghouse, which would have likely been on the roof of the tank. It must have been plugged up, and it must have been blown off the roof.

So, I knew what I was looking for, but I did not know exactly what this one looked like. In my walking around, I spotted what looked like an outhouse or one of those portable potties you see around construction sites, but it was a good bit larger. It was about fifty yards from the tank, and it looked suspiciously out of place for some reason I couldn’t put my finger on. I began to get that tingle I sometimes get when I know I have figured something out and am about to prove it.

Sure enough, when I walked over to the “outhouse” and opened the door, I saw that it was a baghouse. As I expected, all the socks were so jammed packed with quicklime that no air could possibly get through them. They looked like giant, white sausages about to burst out of their skins. I concluded that the motor that shakes the socks out every so often must have failed. After that happened, the socks gradually filled up completely. And then when the supply man hooked up his hose and started his blower, he blew the tank roof off, along with the baghouse that was installed on it. It looked to me like quicklime had gotten inside the motor and clogged it up, causing it to fail. I could check that later.

I was excited, and I couldn’t wait to show Dan, but I closed the baghouse door and maintained a calm demeanor. “Dr. Dan” I called across the plant yard. “Can you come here just a minute? I want to ask you something.” Dan walked over. I was barely able to stifle my excitement as I opened the baghouse door and asked him, “Do you know what this is?” Dan stood there for a minute looking without seeing. Then the scales fell from his eyes; he was suddenly stunned, and he couldn’t even speak for a few seconds. Then all he could do was gasp, “A BAGHOUSE! A BAGHOUSE!” You found a BAGHOUSE!” Dr. Dan had finally gotten to see a baghouse. He was thrilled, and so was I.