Humidity measurement: some do's and don'ts
Do...
- make use of the manual, and of manufacturer's advice
- have the instrument calibrated, and take account of any calibration corrections required
- let the instrument reach the temperature of the location
- allow time for the humidity reading to stablise (especially for dry gases)
- record measurement results with suitable care
- be clear when expressing humidity differences. A change of 10 % of reading is not the same as a change of 10 %rh
- check any hygrometer that has been exposed to extreme conditions or containments
Don't...
- don't handle humidity sensors roughly. Don't abuse wall-mounted sensors by treating them as coat hooks!
- don't use sensors outside the temperature or humidity range specified by the manufacturer - this could cause a shift in calibration
- don't expose sensors to condensation - unless you know they can definitely tolerate this
- don't 'mix and match' humidity probes with different electronics units - unless they are definitely designed for this
Watch out for...
- droplets, or stray water in any form: if present, humidity measurements may be misleading
- dust - bad for most hygrometer types
- pressure differences (dew point) or temperature differences (relative humidity)
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