Carbolite CAF DIGITAL IMAGING - Manual (Page 19)

CAF Digital Imaging
MF36-3.21
page 19
Selecting ‘Record’ will automatically set the furnace controller to ‘Run’ and start the furnace
program. The yellow ‘test in progress’ light will illuminate on the control panel. The green
Standby Mode indicator will go out.
Note: Do not open the furnace door when the ‘test in progress’ light is illuminated. See section
1.1.
The furnace will dwell at its current set point (start temperature) for 5 minutes then ramp to the
selected target temperature at the pre-selected ramp rate.
Note: Avoid operating the furnace at unnecessarily high temperatures and ramp rates. See
sections 4.5.1 and 4.5.2.
When the furnace reaches the pre-selected ‘Start recording’ temperature, images will be saved at
the pre-selected ‘Temperature interval’ up to the ramp target temperature. As the images are
stored the black text box will flash across the top of the image window.
When the furnace has reached the selected target temperature it will dwell for 1 minute then the
controller will switch off allowing the furnace to cool naturally to its set point (start
temperature). The software will stop recording images when the furnace temperature stops rising,
select the ‘Stop’ button to exit record mode. Alternatively the controller, and image recording,
can be stopped at any time during the test by selecting the ‘Stop’ button.
Note: Periodically a red box containing the words ‘Communication failure’ may appear above
the ‘Sample Identification’ box, this occurs when the computer is busy with another task during
communication with the furnace controller and should only appear momentarily.
4.5.4.5 The furnace controller program can also be started and stopped independently of the CAF test
software:
To start the program: press the Run/Hold button () on the front of the controller, the word RUN
will illuminate at the side of the button to signify that the program is running.
To stop the program: hold down the Run/Hold button () on the front of the controller until both
the words RUN and HOLD at the side of the button are not illuminated.
4.5.5 Gas Set-Up.
The gas sequence is started automatically by the furnace controller. The gas sequence is as
follows:
When the instrument switch is turned on the control system will open the ‘purge’ gas solenoid
valve and purge the work tube for a duration of 5 minutes.
When the controller program is initiated the ‘purge’ gas solenoid valve will open and purge the
work tube for 5 minutes (during the 5 minute dwell period of the program). After the 5 minute
purge the ‘purge’ gas is turned off and the test gas solenoid valve is opened.
Note: If the ‘purge’ gas supply is interrupted at the start of the test or during the test an alarm
buzzer will sound and a warning light will illuminate on the control panel. See fig 11. This alarm
will continue until the furnace is turned off and the ‘purge’ gas supply is restored. While the
alarm is activated the control system will not allow introduction of ‘reducing’ gas. See also
section 4.1.2
Note: During the test the yellow ‘test in progress’ light will illuminate on the control panel and
the green Standby Mode indicator will go out. Do not open the furnace door when the ‘test in
progress’ light is illuminated. See section 1.1.
The desired test gas is selected using the ‘oxidising’ - ‘reducing’ gas selector switch on the front
of the furnace control panel. See fig 11. The test gas will flow for the duration of the controller
program.
At the end of the controller program or if the program is interrupted (manual intervention) the
‘reducing’ gas is turned off and the ‘purge’ gas solenoid valve will open to purge the work tube
for a duration of 5 minutes.