Scientech H410 Vector - Manual (Page 27)

27
C
ALIBRATION OF
A
STRAL
 C
ALORIMETERS
U
SING
E
LECTRIC
S
UBSTITUTION
H
EATING
:
For Astral calorimeters the electric substitution heating option must be ordered and installed at the factory when
the calorimeter is purchased. It can not be retrofitted to a calorimeter at a later time. To calibrate using electric
substitution heating proceed as follows.
Figure 4
A. Remove the screws holding the calorimeter's ID tag and remove the plate to expose the circuit board as
shown in Figure 4.
B. Connect the calorimeter to the indicator, turn on the power and let the system equilibrate.
C. Connect a DVM to the test points labeled SUB and HTR on the calorimeter circuit board.
D. Measure the resistance of the substitution heater making sure to subtract the resistance of the patch
cables from the total resistance measurement. Compare this resistance to Rc in the calibration data in
the front of the manual. The two should agree within 2%. If not contact Scientech.
E. Remove the DVM. Connect a power supply to the SUB and HTR test points and connect the DVM to
monitor the power supply.
F. Set up the indicator in the Watts Mode and the 10W range for 25 mm calorimeters or the 3W range for
50 mm calorimeters.
G. Apply Vh volts, stated in the calibration data you received with the calorimeter, to the substitution
heater.
H. If needed, adjust the calibration trim pot, R4 on the calorimeter circuit board, until Wh Watts, from the
calibration data, is displayed by the indicator.