Vaisala PTB210 SERIES Manuel d'instructions télécharger pdf (Page 54)

To verify the humidity readings the programmable logic control was set to escalated

steps of ﬁve percent which was kept within a period of thirty minutes before skipping

to the next level.

Figure 5.2: RH Measurement as a Function of Time

Figure 5.2 gives an account of the chronological sequence of this measurement.

The curve progression may appear a little bit strange at ﬁrst sight. The reason for

that is as simple as partly preventable. The Dewmet Sensor from Michell Instru-

mentations is to be used as a reference. It measures humidity with the dew point

mirror principle. The mirror is cooled down and normaly should be kept around the

barrier of condensation. In this experimental set-up, the reference is placed next to

the chambers air ﬂow which makes it almost impossible to keep the temperature of

the mirror at the dew point level. This is especially problematic at very low ranges

in case of reaching the dew point.

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Vaisala PTB210 SERIES Manuel d'instructions Page 54