Appendix C: Measuring under Special Conditions
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C76IB003EN-E
For a measuring temperature of 20 °C, a drying cartridge must be used under the
following conditions:
To prevent condensation in the measuring cell block
To prevent condensation in the measuring cell block, connect a dry air supply to
the "DRY AIR IN BLOCK" connector at the rear of DMA M using a 3 x 5 mm hose
made of suitable material (e.g. silicone) (see Fig. C - 1).
The dry air supply must be used additionally to the drying cartridge if the
measuring temperature is more than 5 °C lower than the ambient temperature.
The following specifications of the applied air are required:
•
0.2 to 0.3 bar (2.9 to 4.4 psi)
•
Class 5 from ISO 8573-1
•
Max. particle size: 40 µm
•
Max. pressure dew point: 10 °C below measuring temperature
•
Max. oil content: 25 mg/m
3
To regenerate moist ruby gel
The drying cartridge contains beaded ruby gel, a non-toxic drying agent. When
active, the color of the drying agent is red. Ruby gel which has absorbed liquid
turns orange.
Moist ruby gel can be regenerated: Pour the ruby gel into a glass bowl and blow
hot, dry air (max. 130 °C, 266 °F) through it for approx. 5 hours or place it in a
laboratory oven for a few hours (or overnight) until it is red again.
Ambient temperature
Relative air humidity (r. h.)
20 °C
> 70 %
25 °C
> 50 %
30 °C
> 38 %
NOTICE
Never connect hoses containing liquids or moist gases to the "DRY AIR IN
BLOCK" connector as this may lead to damage to the electronics.
NOTICE
Do not use higher drying temperatures than 130 °C (266 °F). Otherwise the
indicator function of the ruby gel is spoiled.
