Date: Wed, 7 May 1997 10:27:51 -0400 (EDT) From: Perry Malouf <pmalouf@access.digex.net> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg1817$foo@default> Subject: hygrometers....
Tom wrote:
> ...I have considered buying an hygrometer.
> Are they reliable or what?
The device I use to measure relative humidity is a sling
psychrometer. It has two thermometers, and the bulb of
one thermometer is kept wet by a wick that's wrapped
around it and immersed in a water reservoir. The
other thermometer is kept dry (normal).
The two thermometers are in a plastic sling, which allows
you to twirl them in the air. After doing this for a
minute or two, there will be a difference in the temperature
reading between the two thermometers. The wet thermometer
will show a lower temperature due to the water evaporation
around its bulb.
The two temperatures are used to adjust a sliding scale,
which then allows you to read the humidity.
I don't know how electronic hygrometers work--so I can't
comment on the accuracy. But a sling psychrometer
is very accurate.
Regards,
Perry Malouf
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