Gas Bags?

I remember, when I was a kid, my father would take me into the city (Chicago) and we always saw these huge cylindrical structures (maybe 150 feet in diameter, 2 or 3 hundred feet tall) that looked like an iron framework with some sort of container inside it. Upon questioning, my father explained to me these were natural gas storage tanks, and the container inside the frame rose and fell according to the amount of gas they had on hand. To this day, I cannot figure out the mechanics of this device, and I don’t see them anymore (although I think there might be a few left near the steel mills on the south side). Anyone have the Straight Dope on these things?

      • St. Louis has a few, two right along I-44 - they’re quite old, but still in use. No new ones, maybe there’s a better way of doing it now. I dunno nutting else. - MC

Long Beach/Signal Hill, CA had one until very recently. The mechanics, as near as I can figure, were based around pressure diferentials. The more gas you pumped into the bag, the higher it rose in its frame. The weight of the bag’s “roof” would keep the whole thing at a higher pressure than the surrounding air. Perhaps this pressure was used to force the natural gas through the city’s gas system. If not for the pressure exerted by the “roof” you wouldn’t get a steady flame on your stove.

This is all conjecture, of course.

PapaBear beat me to the punch, although I think his statement about your stove burner is a bit of a leg-pull.

Saw the one of the 2 along 1-44 in St. Louis burn when I was 10 years old. I lived about 10 miles from there and my buddies and I saw the tower of black smoke and immediately took off on our bikes for it (we were 10 and not really hip to the potential of a large natural gas explosion). A cop caught us trying to cross the rain drainage “river” that separated the tanks from the residential neighborhoods and he just about had a cow. He put our bikes in the trunks of 2 patrol cars and chauffered us home. We were duly bummed.