FPG8601™/VLPC™ OPERATION AND MAINTENANCE MANUAL
© 2007 DH Instruments, a Fluke Company
Page 76
LABEL
DESCRIPTION
Vacuum
reference orifice
diameter (mm)
(numeric entry field)
The minimum connection tube diameter between the vacuum reference
sensor and the FPG8601. This value is typically a diameter internal to the
vacuum reference sensor. The value is used only when thermal
transpiration is active for the vacuum reference sensor.
Vacuum
reference
temperature for
thermal
transpiration
correction
(numeric entry field)
The steady state temperature of the vacuum reference sensor. The value
entered is used to determine the thermal transpiration correction when the
correction is active.
Thermal
transpiration
correction factors
(numeric entry field)
Coefficients
<A>
,
<B>
and
<C>
are standard thermal transpiration
correction factors (see Section 11.3.4). The values must be specified for
the active test gas. Assigning the coefficients for gases other than the test
gas will causes significant errors in the determination of the thermal
transpiration correction.
ATM/Lube Switch
delay time
(scroll bar selection)
The time in seconds between atmospheric pressure readings. Use the
scroll bar to increase or decrease the switch delay time. Changes in
atmosphere (ATM) have a very small yet measurable effect on the FPG.
The change in ATM since the last zero results in a small buoyancy force
that is quantified by
δ
N3 (see Section 2.7.3). While ATM is being read FPG
Tools is temporarily halted. Therefore, making this time too small can add
unnecessary delays to calibrations.
6.6.4.2
<PRESSURE>
All limits related to pressure measurements made by the internal transducer are
defined on this tab. Do not confuse these pressure limits with actual FPG
calculated pressures. The purpose of each limit is defined on the table below.
When a pressure limit is exceeded an “L” or an “A” will be listed in the
<Status> category of the <Diagnostics Display>. This forces a “Not
Ready” condition.
Figure 34. <Internal Limits> <Pressure>
