DDS Calorimeters CAL3K Series, Operation Manual

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DDS CALORIMETERS OPERATIONS MANUAL V1.1 2022 Website: www.ddscalorimeters.com 31
Digital Data Systems (Pty) Ltd.
CAL3K Advanced Bomb Calorimeters
www.ddscalorimeters.com
15 FIRING
The CAL3K automatically fires the sample by sending a very high current through the firing wire, which
glows and ignites the cotton, which in turn ignites the sample. The amount of current to send through
the wire can be programmed.
16 FIRING VOLTAGE 1
The firing voltage is default set at 25.0 volts. The setting depends on the sample and the oxygen
pressure.
The firing voltage must be decreased if the ‘semi-permanent’ firing wire melts too often. You should get
20 to 50 firings out of the wire depending on how corrosive the sample is.
The actual firing voltage is produced by a charging circuit, which takes about 2 minutes to charge. The
charged voltage can be monitored by:
51 READ FIRING VOLT 1
Type ESC to end the firing voltage display. The firing takes place automatically after a pre-set time.
The sample can be fired manually:
17 FIRE MANUAL 1
The firing wire can be heated at any time as long as the vessel is in the well and the firing wire is
present.
The manual firing should be avoided during routine operations.
16 COMPENSATION
Compensations are a set of factors which are calculated after each calibration. They describe how a
result should be treated if the present conditions differ from the calibration conditions.
In simple practical terms: The ambient condition has changed by 1C down then the result is 0.001C up.
Of course, it is more complex. Mainly because there are 5 conditions with various effects and various
magnitude. And, there are many (max 15) calibrations to choose from.
The compensation factors are calculated by an AI (Artificial Intelligence) module after each calibration
when there are more than four already saved.
These compensation factors change with:
Vessel construction: Deflector plate, Crucible holder, firing wire length, cotton length
CAL3K construction: Ambient temperature, ATC temperature (if installed), Ventilation
Vessel age and surface condition