Unseen Hazards


Dan Kovalchik

A few years ago, a safety engineer at the Kennedy Space Center was sifting through his mail when something caught his eye; a safety alert for "explosion-proof" flashlights. Some of these flashlights, the warning stated, had slipped past the manufacturer's quality control and therefore couldn't be guaranteed to be explosion-proof.
The engineer, new on the job, didn't know that the term "explosion-proof" is applied to devices that have been hermetically sealed, making them safe to use in an explosive atmosphere. Guided by an entirely different interpretation of the message, he grabbed the phone, called the bomb squad, and told them to get their defusers ready: A number of flashlights at the space center were about to blow.
At least that's the way legend has it. But considering the nature of the KSC safety engineer's job, the story is entirely believable. As a graduate of innumerable safety classes during my 12 years at KSC, I can attest that these engineers know better than anyone that the rocket business can be extremely hazardous to your health. Who can blame them if they react accordingly? After all, there are thousands of professionals at the center who, during the course of the day, work with an astonishing array of substances capable of depriving a person of life or limb. Need proof? Go check out NASA's stockpile of caustic solvents and ordnance devices; you'll think the words TOXIC, VOLATILE, FLAMMABLE, and LETHAL were coined especially for KSC's inventory.
While each of these materials commands respect, there is one ugly customer that is the most fearsome of the chemicals stored at the rocket ranch. It's called a hypergol. The space shuttle uses two in particular, nitrogen tetroxide and monomethyl hydrazine, names that strike terror in the hearts of safety inspectors.
These two substances are useful because of one interesting property: Mix them together and they explode. This, of course, is why space rangers think these compounds are so attractive. Hypergols don't care whether they're sitting on the launch pad or orbiting Uranus. The equation remains the same -- mix them and they explode. Propulsion engineers get misty-eyed when they talk about hypergols.
The technicians who load these fuels tend to get emotional, too, but for a different reason. Hypergols have a special affinity for human skin. Just the briefest exposure to hypergolic vapors means a frantic strip and a 20-minute scrub in a safety shower. And that's just the beginning. Afterwards, you get shipped to the hospital to see if something can be done to stop that pesky hemorrhaging in your lungs.
So although you may have been thinking that a few spoonfuls of hypergols would be just the ticket to get rid of those stubborn toilet stains, you might be getting the idea that these compounds aren't the kinds of things you want to keep under your sink, with or without childproof caps.
And that's precisely the message the safety instructors try to get across: Hypergols Are Bad News. Watch for nitrogen tetroxide's telltale reddish vapor cloud and its pungent, sweetish smell. You won't see hydrazine; it's invisible. But be alert for a fishy, ammonia odor. Get out of the building, check the windsock, run upwind from leaks. And don't be afraid to report any suspicious clouds or odors. Better to be safe than real sorry.
About five years ago one group of technicians took that message to heart. While installing a rooftop satellite dish, they noticed a fishy ammonia odor. But as far as anyone knew, monomethyl hydrazine had never been stored anywhere near the building in question. Surely the workers were wrong. Perhaps, as their supervisor suggested, the techs had fabricated the story in order to get off a hot Florida roof in August.
Fabrication or not, you don't ignore reports of hypergol leaks. Engineers quickly pulled out their electronic sniffers, donned their protective suits, and headed for the roof.
When the equipment showed no trace of the deadly vapor, team members doffed their masks. Sure enough, there was a fishy, ammonia odor, which the engineers quickly traced to a vent leading from . . . the men's room.
The investigation summary stated that KSC workers were safe for another day. But the report stopped short of classifying the fumes as non-toxic, non-volatile, non-flammable, and non-lethal, an omission that tends to support the claim made by one of the investigators: that the rooftop gas may have been a fuel source that NASA scientists had overlooked. If that's the case, engineers may be thankful they had not peered into the vent with one of those non-"explosion-proof" flashlights.


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