26
7.3 Test programs
Press the 'cog-wheel' key (Settings/Information)
– Vacuum pump test program:
With this program, the vacuum performance of the furnace
vacuum system can be automatically tested. For that purpose, the
achieved (minimum) pressure in mbar is measured and indicated.
If the pressure value is below 80 mbar, the vacuum performance
of the system is adequate.
– Keypad test program
– Heating muffle test program
– Dehumidification test program
– Cleaning program
7.4 Stand-by
We recommend keeping the furnace head closed, especially if the
temperature drops below 150 °C (302 °F).
7.5 Dehumidification program
The condensation of water in the insulation of the firing chamber
and the vacuum pump will result in a lower vacuum and thus to
impaired firing results. For that reason, the furnace head should be
kept closed when the furnace is switched off, in order to prevent the
absorption of humidity. Start the dehumidification program if
required (humidity in the insulation).
7.5 Calibration
Furnace calibration (Silver Test)
The sheathed thermocouple may be subject to changes
with affect the furnace temperature, depending on the
mode of operation. Check furnace temperature with the
‘Silver Test’ at least once a year and adjust if necessary. For
that purpose, the furnace features a special calibration program.
Procedure:
a)
The Furnace must be at operating temperature (switched on for
at least 60 minutes) and have a stand-by temperature of 403 °C
(757 °F).
b) Press and keys to
enter the Options menu.
Then press
key until the
Display shows this screen:
To select the calibration pro-
gram press the ENTER-key.
The following is displayed:
c) Insert silver wire into the Ivoclar
Vivadent sample holder.
d) Place the sample holder with the
silver strip in the centre of the firing plate (6).
e) Press START (if error message Error 14 appears, the furnace
temperature is still too high fort he ‚Silver Test’ (>410 °C/770
°F)). The furnace closes automatically at the correct temperature
and the program starts.
If the silver wire has started to melt (and has a ‚pitted’
appearance) at the end of the program, the furnace
temperature is correctly calibrated (Figure B) If not,
recalibration is necessary.
Recalibration
A change in temperature of
”+/-” 100 °C (180 °F) is possible in
the Programat P300. Select
calibration program to activate the
calibration keys + and –. The
program must not be started for
this purpose. The latest calibration
value is indicated on the Display.
– If the silver wire has not started
to melt after the Silver Test,
recalibrate using the +key
(Figure A)
– If the silver wire has melted
down to a ball after the Silver
Test, recalibrate using the –key
(Figure C).
Every time a calibration key is
pressed, the set temperature
changes by 1 °C (1.8 °F)
Experience has shown that a
recalibration of 5 °C (9 °F) is
appropriate, which means pressing
the relevant key five times.
While the calibration keys are in use, the calibration value in °C (°F)
is shown in the Display. Entering the calibration value does not have
to be confirmed with ENTER. We recommend that you do not
recalibrate the furnace immediately before it reached the holding
temperature or during the holding time of the Silver Test program.
Repeat the Silver Test until the silver wire starts to melt correctly
(Figure B).
Fig. A
Temperature too low
Fig. B
Temperature just right
Fig. C
Temperature too high
Sample holder
silver wire
Firing plate (6)
Содержание Programat P300
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