We are employing salt baths for generating stable humidity environments for the routine verification of RH instrumentation. This technique provides reproducibility with in ± 0.5% RH, if temperature is controlled with in ± 2.0`C. But these salt baths take five to six hours for stabilization and is very cumbersome to operate.
Has any one come across techniques which are easy to set up and could be used for verification of RH instrumentation (with out employing precision instrumented RH chambers)?
Does the flow-division humidity generator meet your requirements?
Humidity sensors are normally subjected to calibration with the flow-division humidity generator because the time needed for the calibration is very short.
The precision depends on that of the mass flow controllers available but normally higher than that with slat baths.
Thank you Shinsaku,
Yes we can use flow division humidity generators. But they seems to have poor repeatability at lower RH ranges, especially below 40% RH, unless we use multiple flow division strategies.
It seems that the drier of your flow-division humidity generator works improperly. Dual zeolite 5A driers working in turns give a dry air with a dew point temperature of -42°C (0.46% RH at 25°C) and a satisfactory precision over the entire range. Corrosion products coming from the air compressor cause a fetal problems to the flow controllers hence they have to be removed with a centrifugal dryer prior to the molecular sieve driers.
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