Pat Naughtin wrote:
>
> Dear Jim,
>
> I would like to explore the issue of mmHg as a dangerous unit a little
> further.
>
> Let me quote from my original message: 'Because the medical profession is
> using mmHg for blood pressure it must feel right to actually use mercury in
> a glass tube to measure it.'
>
> This raises two questions:
>
> Is the sphygmomanometer that your wife uses a mercury-in-glass device?
Nope. It uses a gauge. Probably a diaphragm gauge since those are
cheaper than bourdon tube gauges. It's been a couple of decades since
I've seen a Hg sphygmomanometer in a health facility. They all use
gauges. I don't think health-care specialists would enjoy going back to
subtracting right and left column heights read from an Hg manometer.
> If you wanted to place a mercury-in-glass manometer in each of your
> laboratories, and in each of your offices, what would be the reaction of the
> occupational health and safety people at your university?
I would seriously jeopardize my job trying that, but more from the
point of view that I would have wasted money on a needless equipment.
It's been several years since I have seen an actual Hg column barometer
in a lab. To the best of my knowledge, we don't even have any Hg
thermometers around anymore. The alternatives to these Hg containing
devices are good enough for our purposes.
As for the reactions, they don't see Hg as being quite the hazard that
they used to, I'm told, but it's still a hazard. Worse, there is no
reasonable rationale for not using the alternatives, which are also
probably cheaper.
Jim
--
James R. Frysinger
Lifetime Certified Advanced Metrication Specialist
Senior Member, IEEE
http://www.cofc.edu/~frysingj
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