Optical Filters; Fused Silica Liner; Detector Temperature Considerations; Conditions That Prevent The Detector From Operating - HP 6890 series Operating Manual

Optical filters

The filters are marked on the edge with the transmission wavelength.
Each filter has a mirrored side which must face the flame when
installed and a colored surface.
The sulfur filter is blue/purple and transmits at 393 nanometers.
The phosphorus filter is yellow/green and transmits at 525 nanometers.

Fused silica liner

The HP 6890 FPD uses an inert fused silica insert liner in the transfer
line. This allows fused silica columns up to 530 m ID to run right to the
base of the flame, minimizing sample tailing or loss on chemically active
sites. The liner is also compatible with standard packed columns.

Detector temperature considerations

The FPD flame produces considerable water vapor. The detector must be
operated above 120°C to prevent condensation.
Unnecessarily high temperatures can cause thermal decomposition of
many thermally labile phosphorus and sulfur compounds.
Detector temperature can have a significant effect on sulfur sensitivity. If
analyzing compounds with high boiling points, the detector temperature
should be set to 25°C above the final oven temperature if allowed by the
temperature limit of 250°C.

Conditions that prevent the detector from operating

D Temperature set below 120_C
D Air or hydrogen flow set at Off or set at 0.0
D Ignition failure
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