Carbolite HTR 11/150 - Manual (Page 5)

HTR
MF30 – 3.07
5
3.0 O PERATION
The instructions for operating the temperature controller are given in a separate manual.
If the furnace is fitted with a time switch, see also the supplementary manual MS03.
If cascade control is fitted, see the supplementary manual MS07.
3.1 Operating Cycle
The furnace is fitted with an Instrument switch. The switch cuts off power to the controller(s), to
the heating elements (via a contactor), and to the vessel drive motor.
Connect the furnace to the electrical supply.
Operate the instrument switch to activate the temperature controller. The controller becomes
illuminated and goes through a short test cycle. Depending on the lid, the motor setting, and the
overtemperature controller (if fitted), the vessel may start to rotate.
Set the temperature controller to the desired setpoint or program – see the controller manual.
Overtemperature option only. If the overtemperature controller has not yet been set as required, set
it and activate it according to the instructions in the appropriate manual.
The furnace starts to heat up. The Heat light glows steadily at first and then flashes as the furnace
approaches the desired temperature or a program setpoint.
Overtemperature option only. If the overtemperature trip operates then an indicator in the over-
temperature controller flashes, and the heating elements are isolated. Find and correct the cause
before resetting the overtemperature controller according to the instructions supplied.
To turn the furnace off, set the Instrument switch to it’s off position; the controller display will go
blank. If the furnace is to be left off unattended, isolate it the electrical supply.
3.2 Vessel & Gas Supply
Only fill the vessel to a level below the central tube extensions, so that powder cannot work along
the tube during operation.
Do not exceed the following maximum weights of load (applicable to silica glass vessels):
HTR 11/75 - 120 gm HTR 11/150 - 950 gm
The vessel oscillation is controlled by a unit on the front panel, which has an on/off switch and a
rotary dial. The dial sets speeds between 1 and 8 cycles per minute. The vessel rotates in alternate
directions through an angle of 315°.
Set the flowmeter to the desired rate of gas flow.
3.3 General Operating Notes
Heating element life is shortened by use at temperatures close to maximum. Do not leave the
furnace at high temperature when not required. The maximum temperature is shown on the
furnace rating label and on the back page of this manual.
Ensure that the vessel is rotating whenever the furnace is at a high temperature, to prevent sagging.
Do not operate the furnace with toxic gases unless suitable exhaust disposal precautions are in
force.
Lightweight ceramic fibre insulation can be marked by accidental contact. Some fine cracks may
be visible on the surface of the insulation, or may develop in the surface of the chamber due to the
progressive shrinkage of the insulation materials. Cracks are not usually detrimental to the
functioning or the safety of the furnace.