Carbolite MTT 12/38/850 - Manual (Page 5)

MTT
MF38 – 3.07
5
3.0 O PERATION
3.1 “MTT 12/38/850” – two zone combustion tube furnace.
The furnace is based on the Carbolite model MTF 12/38/400, but has two independent zones,
giving twice the heated length in total. The two zones are wound on a single ceramic tube (38/46 x
900mm long); each zone is approximately 400mm length. The zones are separated by
approximately 10mm because of the requirement for separate overtemperature systems.
The extended control box type CBT is used for the base.
The zones are independently controlled. Each has independent overtemperature which acts only on
its own zone.
This manual only describes furnace operation. For all other details about the use of this furnace as
a special model for Carbon-14 & Tritium analysis see the separate process Instructions.
3.2 Operating Cycle
The furnace is fitted with an instrument switch. The switch cuts off power to the controllers and
also to the heating elements via a contactor. There is also a Heater switch which can be used to
disconnect power to the elements without switching off the controllers. Heat lights indicated when
controlled power is being supplied to the elements. The instrument layout is as follows:
Operate the instrument switch to activate the temperature controller. The controller becomes
illuminated and goes through a short test cycle.
Set the temperature controllers to the desired setpoint or program - see the supplementary
controller manual.
If the overtemperature controllers have not yet been set as required, set them and activate them
according to the instructions in the supplementary manual for the overtemperature controller.
Switch on the Heater switch, located on the instrument panel. The furnace starts to heat up. The
Heat lights glow steadily at first and then flash as the heating zones approach the desired
temperature or a program setpoint.
If an overtemperature trip operates then an indicator in the overtemperature controller flashes, and
the corresponding heating element is isolated. Find and correct the cause before resetting the
overtemperature controller according the instructions in the supplementary manual.
To switch off power to the heating elements, use the Heater Switch. To switch the furnace off, use
both the Heater switch and the Instrument switch. If the furnace is to be left off unattended, isolate
it from the electrical supply.
heat lights
instrument switch
Controllers
heater switch
Zone 2
overtemp
Zone 1
overtemp
Zone 2
catalyst
Zone 1
control