Casella CEL Thermohygrograph standard model User Manual
Page 8
4.
OPERATING THE INSTRUMENT
1.
Allow the instrument to stabilise to the temperature and humidity of
its 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-metalic temperature element
as convenient and allow the instrument to record for 15 minutes.
3.
Adjust to the correct temperature by turning screw B, set low down
near the bi-metalic temperature strip.
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 turning screw A, set high up near the
rear 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
Screw A (Humidity)
Screw B (Temperature)
Page 8 of 12
THERMOHYGROGRAPH standard
User Manual