Casella CEL Thermohygrograph deluxe model - Manual (Page 8)

4. OPERATING THE INSTRUMENT
1. Allow the instrument to stabilise to the temperature and humidity of
it's surroundings.
If possible, choose a place free from draughts, temperature gradients
or sources of variable humidity.
2. Place a thermometer as near to the bi-metal temperature coil as
convenient and allow the instrument to record for 15 minutes.
3. Adjust to the correct temperature by turning the knurled headed
screw at the base of the temperature coil.
Clockwise rotation moves the pen upwards across the chart.
The adjustment is enough to allow the instrument to fit charts within
our standard range.
It is not possible to change the 50 o C measurement span.
4. Measure relative humidity with a whirling, sling, or other aspirated
hygrometer.
Do not use stationary or un-aspirated types, as this may
cause errors.
5. Adjust the humidity reading by means of the screw located behind
the vent holes on the left hand (drum end) lower corner of the
instrument.
Clockwise rotation moves the pen downwards across the chart.
6. Check the calibration of the instrument every 2 to 4 weeks.
Operation
Page 8 of 12
THERMOHYGROGRAPH deluxe
User Manual