– After pressing the button, the pressure drops on gauge (3) for about 5 seconds and then
it remains constant. Watch it for about a minute. If there is no pressure drop any more,
the complete gas system is seal so that the leakage test is successfully completed.
– Keep holding the button (2) for about one minute. Should there be a continuous pressure
drop, then release the button (2), open the furnace, press and hold the button (2) again. If
the pressure with open furnace remains stable then the leakage is in the furnace area. To
the furnace area belong also the metal dust trap (6), the tube (5) and the moisture trap (7)
underneath the metal filter, the dust filter cartridge on the front panel and the outflow
valve V1.
1. Leakage in the furnace area:
According to experience over years, leakages are almost exclusively in the furnace area. Most
common reasons in the order of probability are: (see graphic below).
- The combustion tube (12) has a crack or a hole due major accumulation of splashes from
the analyzed samples. See graphic below.
- The two small O-rings (9) sealing the top of the furnace are damaged, deformed or dusty.
- The palm grip (8) is not in the right position so that the O-ring, sealing the upper end of
the filter housing, is not properly pressed against the filter housing. Rotate to the right
position (maximum force on the O-ring).
- The O-rings (10) sealing the combustion tube are very unlikely to leak, provided that the
winged nuts fixing the furnace closure are driven normally by fingers. The use of
excessive force is not needed and not recommended.
- The O-ring (11) sealing the furnace with the closing cone is very reliable as well. Only if it
is burned by a hot crucible when taking the crucible from the pedestal, there may be a
sealing problem.
- The tube (5) can be damaged due to aging and pressure.
- The moisture trap underneath the metal filter can be not seal when the glass tube may
crack when fitting it.
- The plunger of the outflow valve V1 jams due to contamination. See chapter “Cleaning
solenoid valves” and “Wiring and gas flow diagrams”.
- The dust filter cartridge is leaking. Either one of the small O-rings sealing the cartridge
leads is not seal or one of the hexagon socket screws on the front of the supporting
fittings is not properly fixed.
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