EF, AF
LF01
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 provided.
3.1 Operating Cycle
The furnace is fitted with a combined Supply light and Instrument switch. The light is on
whenever the furnace is connected to the supply. The switch cuts off power to the controller.
Connect the furnace to the electrical supply. The Supply light should glow.
Operate the instrument switch, located on the front panel, to activate the temperature controller;
the
O
position is
off
, the
I
position
on
. The controller becomes illuminated and goes through a
short test cycle.
Close the furnace door and adjust the temperature controller – see the separate manual supplied.
Unless a time switch is fitted and is off, the furnace starts to heat up.
As the furnace heats up the Heat light glows steadily at first and then flashes as the furnace
approaches the desired temperature.
To switch off, set the instrument switch to
O
. If the furnace is to be left off, isolate it from the
electrical supply.
3.2
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 given on the furnace
rating label and on the back page of this manual.
AF:
The element life can be reduced by use of non-metallic hearth plates or other non-conducting
material covering the hearth. Raise the temperature slowly over the last 300°C, allowing 10
minutes soak at 100°C intervals.
When heating large objects, in particular poor conductors, avoid shielding the thermocouple from
the heating elements. The thermocouple is intended to sense the temperature near the heating
element, but if a large cold object is placed in the chamber it may record the average temperature
of the object and the element, which can lead to overheating of the element. Allow large objects to
gain heat at a lower temperature and then adjust the controller setpoint to a temperature close to
the desired maximum.
When heating materials which produce smoke or fumes, the chimney must be correctly fitted and
unobstructed. Otherwise, soot may accumulate in the chamber and could possibly cause an
electrical breakdown of the heating element.
If the furnace is used to heat materials which emit smoke or fumes, regularly heat it up to
maximum temperature for one hour without load to burn away the soot.
Materials such as case hardening compounds and other reactive salts may penetrate the furnace
chamber lining and attack the wire elements, causing premature failure. Use of a hearth tile may be
advisable: please consult our technical department.
3.3
Use of Probes
Any metal object used to probe into the furnace chamber while the furnace is
connected to the supply must be earthed (grounded). This applies in particular to
metal sheathed thermocouples, where the sheaths must be earthed. The refractory
material of the chamber lining becomes partly conducting at high temperatures, and
the electric potential inside the chamber can be at any value between zero and the
supply voltage. Unearthed probes can cause serious electric shock.
Содержание Lenton AF 11/6
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