Linn High Therm GmbH
HT-1500-GT-VAC-Spezial GRAPHITE
page
22
operating instruction issue 30.10.2018
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done with 2” piping. Inside the furnace chamber a distribution system of ceramic
tubes enables a uniform gas flow from bottom to the top of the furnace chamber.
Two vacuum tight valves are mounted in the gas line in front and after the side
channel blower, because the blower is not vacuum tight and not completely gastight.
To guarantee a oxygen free atmosphere during side channel blower operation the
side channel blower is gas tight housed. The housing is water cooled and is purged
with nitrogen over a flow meter (max. 2 m³/h) with needle valve. In the exhaust gas
line a throttle valve is provided in order to keep the furnace inner pressure at max. 4
– 7 mbar at low gas flow. The temperature of the chamber and the side channel
blower motor is controlled by sensors. A water leakage detector is included too.
A gastight filter will be integrated in the gas recooling system for dust removal. The
filter insert is exchangeable. The filter class is HEPA H 13. A differential converter
will be installed between filter inlet and filter outlet additionally for a supervision of the
filter. When exceeding a certain value an alarm will be generated on the controller so
that the filter can be exchanged in time.
4.13 Cooling water control and emergency water cooling
There are installed two cooling circuits for the furnace and the heat exchanger with
needle valve and flow meter.
In case of failing of the electrical mains two NC ball valves separate the cooling unit
and
two NO ball valves open the connection to the emergency water supply. Additionally
temperature and flow of the water cooling circuit are controlled by two sensors. If the
flow falls down or the temperature reaches a programmed value the cooling is
switched over to emergency water supply and an acoustical alarm is given.
If the water flow meter still shows a low water flow or a higher water temperature
after shifting to emergency water to a given time on the controller (see the
instructions for the controller) the heating will be switched off automatically.
In case of a safety switch off check reasons immediately and
remove failure respectively defects.
The emergency water supplied by the customer requires a flow of min. 2,0 m³/h at
<25°C.