Zero percent humidity

[Chris Gregg]

It is fine to have doubts about the accuracy of this instrument however I 
still have total confidence in it.  Most of these large buildings have no 
humidification systems.  Outside at minus 30 degrees Celsius the humidity 
is not much more than ten percent. It does not take much to dry out the 
inside of the building.  If there are four people in a room the gauge will 
go up five per cent, and if I breathe on it it will go up to sixty then 
right down again.  Most homes with working humidification systems  are 
around thirty percent.  Much above that and the windows will  get 
condensation on them when the weather is cold.  The moisture runs down the 
windows and rots the sills.  As the temperature rises so does the 
humidity.Two things to consider.  Firstly, this is one of the dryest places 
on the Planet and secondly we are so used to looking at the units put out 
by Dampp Chaser or Radio Shack that are not very accurate.

Chris
  At 06:33 AM 1/7/2004, you wrote:





>Chris,
>
>Hanna Instruments is a good organization that makes decent quality low-cost
>instrumentation.  However, keep in mind that this instrument was really
>designed for applications in which the humidity is above 10% RH.  In fact,
>if you consider that the accuracy claim is 3% full-scale, that means even
>at 10%RH, you can be off by plus or minus 3% - that's a 6% range of
>inaccuracy at this low level of humidity.
>
>I believe OSHA requires a minimum of 20% RH in public buildings (which is
>still too low in my estimation) so I would almost assume that the
>instrument you purchased is not working properly or maybe has a calibration
>issue.  You may want to call Hanna and get their opinion.  They have good
>customer service and should be able to take care of the problem.  If the
>humidity was really down in the single digits in a public school like this,
>it would be a very unhealthy environment indeed.
>
>I have a hygrometer I purchased from Daigger Instruments (www.daigger.com)
>and the lowest I have ever measured was around the 10-15% RH.  So again, my
>opinion is to check with Hanna to see if there may be a problem with the
>instrument you purchased.  If you can afford it, it is also a good idea to
>get two hygrometers from two different manufacturers.  That way, one can
>sort of act as a check for the other.  If they both read approximately the
>same, your in good shape but if one is way off from the other, there is an
>obvious problem.
>
>Anyone else care to comment?
>
>Corte Swearingen
>Chicago
>
>
> 
>
>                       Chris 
> Gregg
>                       <cdgregg@telus.ne        To:       Pianotech 
> <pianotech@ptg.org>
>                       t>                       cc: 
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>                       Sent by:                 Subject:  Zero percent 
> humidity
>                       pianotech-bounces 
>
>                       @ptg.org 
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>                       01/06/2004 
> 11:19
>                       PM 
>
>                       Please respond 
> to
>                       Pianotech 
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>I have a fairly accurate hygrometer.  I bought it from a scientific
>instrument supply company.  I have been using it for the past year and have
>
>been delighted with the performance. A description of it can be seen at
>http://www.hannacan.com/fiches_techniques/HI98601.pdf
>Up here in the far North we have just been going through a cold spell  with
>
>an mass of Arctic air over us.  I knew it was dry in some homes, have had
>the humidity down to 5 to 8% at times, however this is nothing compared to
>some public buildings that have music schools in them.  I was in one
>yesterday that recorded 2.7 percent in one room and this evening I was in a
>
>building that actually took the gauge down to 0% for a few moments.  I did
>not know this was possible, however I guess it is.  It must be like sitting
>
>right inside the furnace.  Some of the local piano salesmen tell me they
>sometimes hear things go crack on the showroom floor.  I wonder why?  We
>even have laminated boards that crack in this part of the world.  Keeps us
>busy though.  Install lots of Dampp Chasers around this time of year.
>
>Chris
>
>
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