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HMP260 SERIES

Operating Manual HMP260-U017en-1.5

44 1997-11-25

• Check that the reading corresponds within the desired accuracy to the

reading in the calibration table. If not, adjust the second point with the

arrow switches to the correct value and press ENT. At the second

calibration point the second LED from the left flashes.

The basic capacitance of the new sensor may differ considerably from that of

the previous one. Therefore the corresponding humidity reading of the

transmitter may be below 0 %RH at the low or above 100 %RH at the high

calibration point. However, the current/voltage reading of the analogue output

shows only the minimum or maximum value of the selected current/voltage

scale and the output value may not change even though the arrow switches are

pressed several times. If this happens, press the up or down arrow switch

continuously to bring the output back into the selected scale; this may take as

long as half a minute.

6.1.4 Humidity calibration table

Temperature °C 15 20 25 30 35

°F 59 68 77 86 95

LiCl %RH *) 11.3 11.3 11.3 11.3

4...20 mA 5.81 5.81 5.81 5.81

0...20 mA 2.26 2.26 2.26 2.26

0...1 V 0.113 0.113 0.113 0.113

0...5 V 0.565 0.565 0.565 0.565

0...10 V 1.13 1.13 1.13 1.13

NaCl %RH 75.6 75.5 75.3 75.1 74.9

4...20 mA 16.10 16.08 16.05 16.02 15.98

0...20 mA 15.12 15.10 15.06 15.02 14.98

0...1 V 0.756 0.755 0.753 0.751 0.749

0...5 V 3.780 3.775 3.765 3.755 3.745

0...10 V 7.56 7.55 7.53 7.51 7.49

Table 1 Greenspan's calibration table

*) LiCl solution must not be used or stored in temperature below +18 °C,

otherwise the equilibrium humidity of the salt solution changes permanently.

6.2 Temperature calibration

The temperature channel has been calibrated at the factory and since it is very

stable, calibration should be performed only when there is strong reason to

believe that the adjustments have changed.

Temperature calibration should be made against some accurate temperature

reference. It can be done either using the press switches inside the housing,

through the serial bus or the menus on the local display. Either a one point or a

two point calibration can be done.

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