Review on Thomas Traceable Hygrometer Thermometer Barometer by Sam Simone

It is quite unusual for a hygrometer under $200 to come with an individually numbered certificate of calibration. This one does. However, since it only comes with a one-point calibration (23°C, 46% RH), I tested mine at various temperatures and relative humidity levels. Checking the temperature was easy for me: first I calibrated the digital thermometer in ice water and in boiling water, then I compared this device with this thermometer (I could not directly check this device in water because it is unlike this thermometer the only device that cannot be submerged in water and this device also only displays up to 50% C). For humidity, I used the only calibration method that doesn't require multi-kilogram equipment: the classic brine method. Place the probe in a sealed container over a saturated solution of NaCl in water and the relative humidity should be very close to 75% (after a sufficient time to stabilize). Above a saturated solution of MgCl in water, the relative humidity should be very close to 33%. At all of the temperatures I've tested and at both of the relative humidities I've tested, this unit met advertised specifications of +/- 1 degree C for temperature and +/- 3 percent RH over the mid-range to +/- 4 percent. RH somewhere else. I have no way of checking the accuracy of the barometer readings. Comparing the temperature readings, I noticed that my other digital thermometer responded to temperature changes much faster than this device; This is to be expected since the temperature and humidity sensor on this device is physically much larger than the simple temperature sensor found on any other device. Therefore, if only temperature is required, a simple device consisting only of a thermometer is preferable. For humidity, this device is pretty accurate; To get much better relative humidity accuracy would require spending a significant amount of money.