Carbolite RHF Series 3 litre - 35 litre - Manual (Page 5)

RHF
MF07 – 3.10
5
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.
3.4 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.
3.5 Operator Safety
The furnace incorporates a safety switch which interrupts the heating element circuit when the
door is opened. This prevents the user touching a live heating element, but also prevents the
furnace from heating up if the door is left open. The operation of this switch should be checked
periodically – see section 4.1.2.
Avoid burns: furnace surfaces can be hot. Before you remove a hot object from the furnace make
sure you have a safe place to put it down.