[time-nuts] Temp/Humidity control systems?
William H. Fite
omniryx at gmail.com
Thu Oct 27 15:32:57 EDT 2016
Just for the fun of it, here is how NIST measures humidity.
On Thu, Oct 27, 2016 at 3:30 PM, William H. Fite <omniryx at gmail.com> wrote:
> NIST-traceable hygrometers are readily available in the $200-$400 range.
> Or you can get a couple of airtight boxes of precisely the same volume and
> go gravimetric.......................
> On Thu, Oct 27, 2016 at 9:43 AM, Ron Bean <time at rbean.users.panix.com>
>> >* You cannot "feel" absolute humidity, always measure it.
>> And since this is time-nuts: Measuring humidity accurately is tricky.
>> According to people who have tested them, commercial electronic humidity
>> sensors, when tested in a lab, have never come anywhere close to the
>> accuracy claimed in the data sheet. The best you can hope for is
>> consistent readings, not absolute accuracy.
>> The exception is the "cold mirror" type of sensor, which measures the
>> dewpoint by cooling a mirror and bouncing a light off it to sense the
>> temperature where dew condenses on it. Those are expensive, and they
>> require maintenance to keep the mirror clean.
>> BTW some of us are more sensitive to humidity than others. I can't tell
>> you the RH of a room, but I can tell you when it's too dry for comfort.
>> I want it as close to 50% as I can get it without growing mold on the
>> walls. Some "experts" claim that 30% is good enough for anyone, but
>> they're wrong.
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Intelligence has never been proof against stupidity.
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