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QUI-1057
Page 11
Markes International Ltd
T:
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capillary chromatography is produced without on-column focusing and with desorption flows as low as 2
ml/min. This facilitates splitless operation with high-resolution capillary GC.
2.1.6
Trap filters and seals
As with the sample tube, the cold trap is sealed into the gas flow path of UNITY 2 via O-rings, which seal on
the outer wall of the trap tube. At the cool non-valve end of the trap, the O-ring is backed up with a porous
PTFE filter to prevent contamination of the pneumatics in the event of sorbent particles migrating out of
the trap. The user has access to this O-ring seal and filter in the connector (see Technical Support
Manual), but a Service visit is required to access and change the trap O-ring seal in the heated valve. As
the cold trap is only changed infrequently, the seals will rarely, if ever, need to be replaced. It is
recommended that UNITY 2 is professionally serviced once per year and that the valve-end seal be
changed as part of this annual maintenance operation.
2.1.7
Split filters
There is a split filter tube packed with charcoal (
SERUTD-5065
) on the split line upstream of the on/off
solenoid and needle valves. This prevents the split portion of the sample from contaminating the valves
and from reaching the laboratory air. The flow path up to the charcoal filter is heated and constructed of
inert-coated, stainless steel tubing. The split filter itself is the same size as a standard sample tube and
may be readily replaced by a clean sorbent tube if the split effluent is to be re-collected for repeat
analysis, see Section 3.6.5. The split filter (or re-collection tube) is sealed into the split flow line using
easy-connect, Viton O-ring seals and by operating a lever in the same manner as the sample tube. The
sampling end/grooved end of the re-collection tube should point to the rear of the instrument.
Conventional charcoal split filters will become contaminated over time and should be reconditioned or
repacked when required.