DH Instruments GFS2102, Operation And Maintenance Manual, Page: 150 / 206

GFS2102™ OPERATION AND MAINTENANCE MANUAL
© 2007 DH Instruments, a Fluke Company Page 134
5.5.6.3 [LIMITS]
Figure 86. GFS Configuration [Limits] Tab
Table 56. GFS Configuration Editor [Limits] Tab Fields
FEATURE DESCRIPTION
Balance PRT Auto
Zero Limit (C)
(required numeric
entry)
The maximum change in temperature since the last Auto Zero. If the change in
temperature exceeds the limit, a warning message displays on the status bar and a “Z”
displays in the ready indicator on the GFS Run Screen.
Change in temperature has a significant impact on zero drift. A
significant change the balance PRT temperature over the course of one
accumulation can result in faulty GFS flow values. Higher flow rates
(greater than 3 slm) are not impacted as much as lower flow rates.
Maximum balance
PRT temperature
rate(C/m)
(required numeric
entry)
Indicates the maximum allowable change in the balance PRT in °C per minute. The
balance is sensitive to rapid changes in temperature. If the temperature rate of change
exceeds the limit, a warning message displays on the status bar and a “C” displays in the
ready indicator on the GFS Run Screen (see 5.1.5.2.1, GFS Control Panel). System
operation should be suspended until the rate of change limit is met.
Maximum cylinder
probe temperature
offset (C)
(required numeric
entry)
Define the maximum acceptable difference between the temperature measurements of
ProbeTH1 and ProbeTh2. If the temperatures difference is more than the defined value, a
“P” displays in the ready indicator on the GFS Run Screen. A significant difference
between the probes represents a calibration offset or a significant temperature fluctuation.
Both issues can effect the GFS flow determination.
Dew Point
temperature offset
(C)
(required numeric
entry)
The dew point displayed on the GFS Diagnostics Run Screen is an estimate of the
temperature at which water vapor will form on the reference gas cylinder. Since the dew
point is only an estimate it is important to stop data collection at a safe distance above the
calculated value to avoid erroneous data.
Enter a temperature value that represents how close to the dew point temperature that the
reference gas cylinder can approach. When the reference gas cylinder temperature
decreases beyond this limit relative to the dew point temperature, a “D” displays in the
ready indicator on the GFS Run Screen.