[cuban leaf]

The news just hit: They are releasing air out of gas lines in Soloma. Man, I feel for the people that live within a mile or less of that plant. It was dang loud way out our way. I can only imagine what it was like there.

So, the siren must have been a coincidence - or someone was LITERALLY scared to death. ;)

[Steely Tom]

There have been some bad gas pipeline incidents in recent years. There was one in California some years back that caused many deaths (I think it was in San Francisco or Oakland). There was also one in a rural area in the Eastern United States a few years ago that was quite destructive.

I think federal regulations on the pipeline companies were tightened in the wake of those incidents, and they now have to do a lot of testing and vent to atmospheric pressure if they detect even the slightest hint of a leak anywhere. The lines are punctuated by valves at intervals, but those valves can be pretty far apart.

I would take the "releasing air" story with a grain of salt, but perhaps they were doing some sort of high-pressure test with air before bringing a section back into service after a repair cycle.

If it was a test, they undoubtedly test to a pressure somewhat higher than the operating pressure of the pipeline. If they have to release — say — twenty miles of pressurized line, and the line is the usual 36" size, that would be an awful lot of compressed air, millions of cubic feet when it expands to ambient pressure.