Carbolite VST 17/-- - Manual (Page 6)

1700° Tube
6 LMF32C – 1.07
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 LS03.
If cascade control is fitted, see the supplementary manual LS07.
2.9 Operating Cycle
The furnace is fitted with an instrument switch. The switch cuts off power to the controllers and
contactor
.
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.
Adjust the main temperature controller – see the controller manual.
Set the overtemperature controller to a temperature a little (say 15°C) above the maximum
setpoint of program temperature, 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(s) glow(s)
brightly at first, more dimly as the furnace temperature approaches a program setpoint.
If the overtemperature trip operates then an indicator or message in the overtemperature controller
flashes, and the heating elements are isolated. Find and correct the cause before resetting the
overtemperature controller according to the instructions in the appropriate manual.
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.
2.10 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. The furnace can be cycled between room
temperature and maximum without a detrimental effect on element life - but see the notes on tube
life.
On first installing the elements, and on subsequent element replacement, run the furnace at
1500°C for an hour to create a protective glaze on the element surface.
The furnace elements are very susceptible to mechanical shock. Take great care when moving the
furnace.
Light weight ceramic fibre insulation can easily 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.
2.11 Operator Safety
Ceramic materials used in furnace manufacture can become conduction at high temperature.
Avoid using conductive tools within the work tube without first isolating the elements. The
elements are isolated (via a contactor) when the instrument switch is off.
If a metal work tube is used, it must be earthed (grounded). Note that the furnace temperature
should be limited if a metal tube is used.
Ensure that there are no inflammable objects placed in such a way that the work tube could break
and fall on them.