Recalibration of Relative Humidity Probes

[CC Solutions]

Hi Sam,

I ran calibration tests on my Tramex probes, although I felt like the Lone Ranger doing it!! I have been told my probes are the only ones that ever get sent back to the manufacturer..... Hmmmmm, that tells me people aren't checking their probes!

Tramex includes a vial of 75% salt solution. The procedure is to insert a probe into the salt solution vial and place the assembly in an area where it is not subject to fluctuations of temperature, light, and humidity. They suggest a closed drawer. Allow the probe to acclimate for a minimum of 2 hours. The probe should read within 3 percent of 75% RH. If it is not, repeat the test for another 2 hours.

Now let's stop and think about what the manufacturer just told us to do. Put their probe in a salt solution that we know is 75% RH. Let the probe sit 2 hours. (2 hours!!!!!) If the probe doesn't read 72% - 78% (wow, that's a range!) then let it sit for 2 more hours!!!

Now you are expected to take that probe to the field and install it in a hole and wait 45 minutes and trust the reading you get??? C'mon.... What if the probe reads 78%? Is the slab good? Could it be off by 3%? Maybe it is, but the other way!! Maybe the slab is actually 81%!! And we're not testing in a drawer here, we're in an area where air is flowing, sunlight is going across the floor ( readings will change if sunlight warms the probe barrel!)

So I always marked my probes with a sticker showing how far off they were on the last test. Now I had I guys favoring the low reading probes.....

After years of fighting with various probes, I went with Wagner and never looked back. I tested the Wagners every way I could and they always gave consistent dependable results. When I put 6 Tramex probes in a confined slab area (testing purposes) I would get 6 widely spaced readings. 6 Wagners gave me one reading.

I should say, I do not work for Wagner! I am an independent consultant that (in a previous capacity) took advantage of an almost unlimited budget for testing and determining the causes and remedies of flooring failures nationally.