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<div dir="auto">Waller's assrrtion is not true. My vessels are at constant RH for years at a time. The HOBO's monitor that. That's reliable. That's the reason you use a large volume of liquid for a small space. It's also the reason you keep dumping in NaCl
until it fills the bottom of the vessel. It's actually a simple phase rule problem.</div>
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<div>If anyone is interested, I have a bunch of scientific papers that utilize this technique. </div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Robert Waller <rw@protectheritage.com><br>
<b>Sent:</b> Wednesday, October 13, 2021 11:21:24 AM<br>
<b>To:</b> Tacker, Christopher <christopher.tacker@naturalsciences.org>; Lennart Lennuk <Lennart.Lennuk@loodusmuuseum.ee>; nhcoll-l@mailman.yale.edu <nhcoll-l@mailman.yale.edu><br>
<b>Subject:</b> RE: [Nhcoll-l] [External] easy way to calibrate temperature humidity sensors</font>
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<p class="x_MsoNormal"><span lang="EN-CA">Thanks for posting this helpful information Chris.</span></p>
<p class="x_MsoNormal"><span lang="EN-CA">It appears in the picture that there is a large volume of liquid solution.</span></p>
<p class="x_MsoNormal"><span lang="EN-CA">To achieve reliable RH control a slurry with some solid above the level of the solution is required. Otherwise there will be stratification of more dilute solution across the top of the solution leading to a substantially
higher than nominal RH level.</span></p>
<p class="x_MsoNormal"><span lang="EN-CA">Rob</span></p>
<p class="x_MsoNormal"><span lang="EN-CA"> </span></p>
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<p class="x_MsoNormal"><b>From:</b> Nhcoll-l <nhcoll-l-bounces@mailman.yale.edu> <b>
On Behalf Of </b>Tacker, Christopher<br>
<b>Sent:</b> Wednesday, October 13, 2021 9:22 AM<br>
<b>To:</b> Lennart Lennuk <Lennart.Lennuk@loodusmuuseum.ee>; nhcoll-l@mailman.yale.edu<br>
<b>Subject:</b> Re: [Nhcoll-l] [External] easy way to calibrate temperature humidity sensors</p>
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<p class="x_MsoNormal"> </p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman",serif; color:black">The link online to the paper is <a href="https://urldefense.com/v3/__https://nvlpubs.nist.gov/nistpubs/jres/81A/jresv81An1p89_A1b.pdf__;!!HYmSToo!OZhDEgKay44ghmCSeJppH58LLmoUCqukf76pNDOwMEh2lYUfecpJK6c6C1zKckqlG-j1dHlSrloNEQ$">https://nvlpubs.nist.gov/nistpubs/jres/81A/jresv81An1p89_A1b.pdf</a></span></p>
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<div id="LPBorder_GTaHR0cHM6Ly9udmxwdWJzLm5pc3QuZ292L25pc3RwdWJzL2pyZXMvODFBL2pyZXN2ODFBbjFwODlfQTFiLnBkZg.." style="margin-top:12.0pt; margin-bottom:12.0pt; min-width:424px">
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<p class="x_MsoNormal"><span style="font-size:16.0pt; font-family:"Segoe UI Light",sans-serif"><a href="https://urldefense.com/v3/__https://nvlpubs.nist.gov/nistpubs/jres/81A/jresv81An1p89_A1b.pdf__;!!HYmSToo!OZhDEgKay44ghmCSeJppH58LLmoUCqukf76pNDOwMEh2lYUfecpJK6c6C1zKckqlG-j1dHlSrloNEQ$" target="_blank"><span style="text-decoration:none">Humidity
fixed points of binary saturated aqueous solutions</span></a></span></p>
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<p class="x_MsoNormal"><span style="font-size:10.5pt; font-family:"Segoe UI",sans-serif; color:#666666">JOURNAL OF RESEARCH of the National Bureau of Standards- A. Physics and Chemistry Vol. 81 A, No.1 , January-February 1977 Humidity Fixed Points of Binary
Saturated Aqueous Solutions</span></p>
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<div id="LPMetadata906659">
<p class="x_MsoNormal"><span style="font-size:10.5pt; font-family:"Segoe UI",sans-serif; color:#A6A6A6">nvlpubs.nist.gov</span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman",serif; color:black">The paper is also attached. I've included a picture of the setup I use for controlled humidity experiments. I use a HOBO sensor to monitor the humidity
and temperature, inside the lid. </span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman",serif; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman",serif; color:black">Regards,</span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman",serif; color:black">Chris Tacker</span></p>
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<p class="x_MsoNormal"><b><span style="color:black">From:</span></b><span style="color:black"> Nhcoll-l <<a href="mailto:nhcoll-l-bounces@mailman.yale.edu">nhcoll-l-bounces@mailman.yale.edu</a>> on behalf of Lennart Lennuk <<a href="mailto:Lennart.Lennuk@loodusmuuseum.ee">Lennart.Lennuk@loodusmuuseum.ee</a>><br>
<b>Sent:</b> Wednesday, October 13, 2021 3:47 AM<br>
<b>To:</b> <a href="mailto:nhcoll-l@mailman.yale.edu">nhcoll-l@mailman.yale.edu</a> <<a href="mailto:nhcoll-l@mailman.yale.edu">nhcoll-l@mailman.yale.edu</a>><br>
<b>Subject:</b> [External] [Nhcoll-l] easy way to calibrate temperature humidity sensors</span>
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<p class="x_xmsonormal"><span lang="ET" style="color:black">Hi!</span><span lang="ET"></span></p>
<p class="x_xmsonormal"><span lang="ET" style="color:black"> </span><span lang="ET"></span></p>
<p class="x_xmsonormal"><span lang="ET" style="color:black">In our herbaarium we have one quite old and one new temperature humidity sensor.</span><span lang="ET"></span></p>
<p class="x_xmsonormal"><span lang="ET" style="color:black">The data is quite diferent though these sensors are placed in the same spot.</span><span lang="ET"></span></p>
<p class="x_xmsonormal"><span lang="ET" style="color:black"> </span><span lang="ET"></span></p>
<p class="x_xmsonormal"><span lang="ET" style="color:black">Do you know any good and cheap ways to calibrate those senors?</span><span lang="ET"></span></p>
<p class="x_xmsonormal"><span lang="ET" style="color:black"> </span><span lang="ET"></span></p>
<p class="x_xmsonormal"><span lang="ET" style="color:black">Best regards!</span><span lang="ET"></span></p>
<p class="x_xmsonormal"><span lang="ET" style="color:black">Lennart Lennuk</span><span lang="ET"></span></p>
<p class="x_xmsonormal"><span lang="ET" style="color:black">Head of collections</span><span lang="ET"></span></p>
<p class="x_xmsonormal"><span lang="ET" style="color:black">Estonian Museum of Natural History</span><span lang="ET"></span></p>
<p class="x_xmsonormal"><span lang="ET" style="color:black">+372 6603404, 56569916</span><span lang="ET"></span></p>
<p class="x_xmsonormal"><span lang="ET"> </span></p>
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