User guide

Detectors 10
Advanced User Guide 327
Auto Adjust Bead Recommended On. When On, the automatic
adjust offset process starts when the bead reaches the
temperature setpoint after having been turned off or cooled
below 150 °C. Auto adjust starts after Dry Bead hold time, if
enabled. Auto Adjust Bead uses the adjust offset feature to
protect the bead—especially new beads—by making sure that the
desired offset is obtained with the lowest possible bead voltage.
When Off, the bead voltage will rise as soon as the Dry Bead
time elapses, or as soon as the temperature setpoint is reached
if Dry Bead is off.
Dry Bead Recommended On. When On, the bead temperature
holds at 150 °C for 5 minutes before continuing to the setpoint.
This allows any condensation to evaporate and be swept out of
the detector.
Blos Bead If using a Blos bead, set to On. For ceramic beads, set
to Off. The Blos Bead On setting restricts the allowable bead
voltage to the range appropriate for this bead.
Maximum Bead Voltage Display only. Shows the current
maximum bead voltage for the configured bead type (4.095 V for
ceramic beads, 1.1 V for the Blos bead).
Automatically adjusting NPD bead voltage
Agilent recommends using the Adjust offset feature to
automatically determine the lowest bead voltage needed to give
the desired response.
When the detector is turned on, the temperature rises at a
controlled rate.
• If Dry Bead is On, temperature holds at 150 °C for 5 minutes to
drive off moisture, then continues to the setpoint.
• If Dry Bead is Off, the temperature rises directly to the
setpoint.
When the temperature reaches the setpoint, the Bead Voltage
gradually rises until it produces the desired output.
Adjust offset
When you enter a value here, or press [On/Yes] to use the stored
value, detector gas flows turn on, the bead heats, and the bead
voltage adjusts until Output is stable and equal to the entered
value. There are five stages of Adjust offset.