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10.5
Use of Probes and Metal Sheathed Thermocouples
10.6
Atmospheres
This product is designed to be used ONLY with inert gases e.g. argon, or nitrogen.
In practice, inert or oxidising gases may be used.
WARNING:DO NOT use combustible or toxic gases within this product.
10.7
Power Adjustment
The product control system incorporates electronic power limiting. Depending on the
model and the destination country the power limit maybe set to 100% or a lower
figure. Where appropriate the power limit parameter OP.Hi is accessible to the
operator, but it should not generally be altered.
See section 5.0 for details of the power limit settings. DO NOT adjust the power to a
level higher than the design level states; this may cause a fuse to blow and could
damage the heating elements.
The power limit may be set to a lower limit if the product is to be used at a low
temperature only: this may give better control stability. It may be set to zero to permit
demonstration of the controls without the heating elements taking power; to resume
heating reset it to its standard value.
10.8
Insulation Cracking
In these furnaces the insulation material is susceptible to surface cracking as a result of
high temperature cycling; this is a normal occurrence and such cracking is not
detrimental to the performance of the furnace.
40
Any metal object used to probe into the product chamber while the
product is connected to the electrical supply must be earthed. This
applies in particular to metal sheathed thermocouples, where the
sheaths must be earthed. The refractory material of the chamber
lining becomes partly conductive 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.
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