HRF
MF05
5
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 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 control circuit.
The Instrument switch does not cut power to the fan: the fan is on when furnace is connected to
the supply.
Connect the furnace to the electrical supply. The Supply light should glow.
Operate the instrument switch 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.
Adjust the temperature – 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.
Unless a time switch is fitted and is off, 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
overtemperature controller flashes, and the heating elements are isolated. Find and correct the
cause before resetting the overtemperature controller according the instructions supplied.
To switch the furnace off, set the Instrument switch to
O
. If the furnace is to be left off, isolate it
the electrical supply.
3.2
General Operating Advice
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.
When heating materials which produce smoke or fumes, the chimney must be correctly fitted and
unobstructed. Otherwise, soot can 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.
3.3
Atmospheres
When an optional gas inlet is fitted there is a label near the inlet saying "INERT GAS ONLY". In
practice
inert
or
oxidising
gases may be used, but
not combustible or toxic gases
. Chamber
furnaces are not gas tight, so it should be understood that gas usage may be high, and that the
chamber is likely always to contain some air. Residual oxygen levels of 1% are to be expected.
3.4
Operator Safety
The furnace has mineral insulated heating elements, and does not require a door safety switch.
Avoid burns. Carbolite can supply tongs, face masks, and heat resistant gloves. Before you
remove a hot object from the furnace make sure you have a safe place to put it down.
4.0
