RTC 2115150301, Owner'S Manual

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checkout with helium, RTC recommends, as a minimum, a trace oxygen analyzer
and combustible gas monitor be used to guide final process settings.
7.4.6.1.
Furnace System Functional Check
First perform the recommended furnace system functional checkout.
Correct any malfunctions, as necessary, before proceeding.
7.4.6.2.Helium Supply Gas
Temporarily connect a supply of helium gas to the hydrogen input line
and adjust the input regulator to 50 psi. Make sure that the hydrogen
flowmeters are completely shut off at this time.
7.4.6.3.Turn On Furnace
Turn on the furnace and bring it up to a fully operational state using the
suggested gas flow settings from your operation manual.
7.4.6.4.Initiate the Hydrogen Operation Cycle
Adjust the hydrogen flowmeters to the same flow rates that the
equivalent nitrogen flowmeters were set at.
7.4.6.5.Check Oxygen Concentration
Check the oxygen concentration inside each zone of the furnace, using a
trace oxygen analyzer. The oxygen concentration can vary considerably,
depending on flow settings; but as long as 100 ppm, or less, is
maintained in the furnace, combustion will not occur. If the
concentration of oxygen is above the 100 ppm limit, increase the flow of
helium in small increments and retest the oxygen level. Allow several
minutes between gas flow corrections and oxygen testing for the
analyzer to stabilize.
7.4.6.6.Check For Escaping Gas
Check each end of the furnace with a helium detector to see if any
furnace gas is escaping. If furnace gas escapes, increase the flow to the
appropriate eductor in small increments and retest.
The eductor operates with a venturi assisted exhaust stack that produces
an approximate multiplication ratio of 10:1. In general, the gas flows
into the furnace chamber and baffles should be balanced by the gas flows
out of the eductor stacks.
For example, if the total flow of gas into the furnace chamber and end
baffles is 1000 SCFH, the flow of gas to each eductor should be as
follows for a two exhaust system:
Total Exhaust = 500 SCFH through each eductor
Drive Gas = 50 SCFH to each eductor venturi