So, where's the mercury?
Brad Thompson, Contributing Technical Editor -- Test & Measurement World, 8/1/2007
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I subscribe to TechRepublic, a useful online source of timely information about all aspects of computing. One entry on the site features several “Creative uses for dead computers.”
Among the subtopics, a photo essay describing Hewlett-Packard’s corporate computer-recycling facilities attracted my attention.
You can no doubt understand my curiosity when I read the following caption that accompanied a photo of a corrugated-board Gaylord bin containing several cathode-ray tubes (CRTs): “Items collected by HP, like these cathode-ray tubes from monitors, are sent directly to a smelter because they contain mercury bulbs, which are considered hazardous to the environment.”
| Read more about Brad's work at the computer recycling facility: "You can't shrink heat," "Tossed any PCs lately?" |
After spending over a half century of my life messing around with electronics as an amateur and as a professional, I believe that I have acquired a general understanding of most aspects of the technology. And as a volunteer at an electronics-recycling facility, I take interest in the components we encounter both as a source of reusable materials and as hazards to my fellow recyclers.
So, where’s the mercury? Trust me…in my career, I’ve deliberately and inadvertently busted quite a few CRTs, and I can assure you that every one of them contained an electron gun assembly, an accelerator anode, a phosphor-coated screen, and a few other doodads, but no bulbs—mercury, tulip, or otherwise. Most of the funnel-shaped glass envelopes in CRTs contain lead, barium, strontium, and other metals that suppress soft x-rays generated during normal operation. But there’s no mercury.
So, where is the mercury? Fluorescent lamps used for backlighting liquid-crystal displays contain traces of mercury. Chances are the writer of the caption erroneously assumed that all computer displays feature identical internal construction. Thanks—or no thanks—to the Internet, a factual error like this can propagate quickly and reappear in dozens of places. Websites that encourage recycling may soon sport references to CRTs with “mercury bulbs.”
We live in an increasingly complicated world that is heavily affected by the benefits and hazards of technology. As electronic-test professionals, we’re in an ideal position to know what’s hazardous in the products we review, and it is up to us to blow the whistle on egregious errors of fact or interpretation of the technologies we know best.
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