If humidity data is important to you, read on.
Lots of talk recently about Humidity sensors. Obviously we are concerned about humidity, and some folks will assume their data is accurate !
Here are a few facts, some folks may not be aware of—
- Most Humidity Sensors in our price point have an accuracy of +/- 3.0% RH, or worse!
- Your new sensor may, or may not be calibrated! Or the calibration is off from the factory (unless I receive a caliper or other measuring device with a “calibration” certificate, consider it NOT calibrated! (Anyone that has purchased calibrated measuring devices, there is usually an extra charge for the calibration)
- Once calibrated, it is not calibrated for life (it will drift)! It “should” be calibrated at some interval. If you test or calibrate annually, you’ll likely catch a faulty or dying sensor before you have trouble with your grow.
Here is a method for testing, same method can be used to calibrate if your device has a calibration option (AC Infinity, and PulsOne, to name a few can be calibrated by the owner). But you gotta make sure your temp measurement is accurate! Refer to the salt table below to reference salt type and temp for the correlating RH reading.
- Place a handful of salt in the bottom of a jar (quart or liter size is fine).
- Add a little water to the jar so that the salt is wet. Note: The goal is to end up with wet salt, not to totally dissolve the salt.
- Place the Relative Humidity Sensor in the jar. Note: Do not get the salt or salt solution on the sensor.
- Seal the jar. Plastic wrap and rubber bands will do. Allow some time (2 to 6 hours) for the air inside the sensor to reach the proper relative humidity level.
- Repeat with a different salt will add confidence in your results, and help eliminate testing error.
- If your sensor doesn’t repeat within ± 3% RH (since that is about as good as they get at our price point), something is fucked up—your testing procedure (is your temp accurate), or your sensor!
Honor is simply the morality of superior men.
@sevans1965 Good info, bro! Thanks for sharing that. I'm going to check the calibration of my unit.
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