6. FPG TOOLS
Page 77
© 2007 DH Instruments, a Fluke Company
Table 21. <Internal Limits> <Pressure>
Options
LABEL
DESCRIPTION
Display warning if
lubrication pressure
changes from limit
by (+/- kPa)
(numeric entry field)
Enter a value that represents the maximum deviation of lubrication
pressure from it’s tare value. If the pressure changes by this amount, a
warning message will display and an “
L
” will appear in the
<Status>
label
of the
<Diagnostics Display>
(see Section
6.3.7
). This status code
forces a “Not Ready” condition. The value entered should be small to
minimize the effect of the
δ
N1 and
δ
N2 corrections (see Section 2.7).
RPT stability
criterion
(numeric entry field)
The maximum acceptable rate of change of pressure for any internal RPT
measurement. The criterion effects the limits on lubrication pressure,
ATM and reference pressure measurements. When the pressure
measurement exceeds the criterion, FPG Tools does not use the new
pressure in any calculations but will display the new pressure on the
proper run screen. Only stable pressure outputs are used in calculations.
Gauge mode
lubrication pressure
(numeric entry field)
The optimum lubrication pressure for gauge mode operation. The internal
FPG regulators must have been factory adjusted for this pressure. When
setting gauge measurement mode, the lubrication pressure must be within
the
<Maximum deviation from mode appropriate lubrication
pressure>
value prior to completing the transition.
Absolute mode
lubrication pressure
(numeric entry field)
The optimum lubrication pressure for absolute mode operation. The internal
FPG regulators must have been factory adjusted for this pressure. When
setting absolute measurement mode, the lubrication pressure must be
within the
<Maximum deviation from mode appropriate lubrication
pressure>
value prior to completing the transition.
Maximum deviation
form mode
appropriate
lubrication pressure
(numeric entry field)
When setting gauge or absolute measurement mode, this value
represents the maximum deviation from the target lubrication pressure
value. If FPG Tools is not able to achieve this pressure, the mode
transition will neither complete nor time-out.
Absolute mode,
vacuum reference
stability criterion
(numeric entry field)
In absolute mode when the
[Config], [System Setup], <Use vacuum
reference sensor for absolute mode correction>
option is selected, this
entry determines how stable the vacuum reference sensor must be to
allow a ready condition. Two consecutive readings (about 1s apart)
cannot differ by the value entered, otherwise, a
"V"
will appear in the
status indicator and the FPG pressure will be forced to a "Not Ready" state.
Vacuum pump
speed at which the
ion gauge can be
activated
(numeric entry field)
Enter the speed of the turbo pump required to achieve a pressure low
enough to safely turn on the ion gauge when zeroing the DUT manifold.
Typically, the maximum speed of the turbo pump should be entered. The turbo
pump cannot reach maximum speed until the pressure is on the order of 1 Pa.
Ion gauge pressure
at which degassing
can be turned on
(numeric entry field)
Enter the maximum pressure at which the ion gauge’s degas option
should be turned on. This parameter is used only when the DUT manifold
is zeroed and the ion gauge is enabled (see Section 5.6).
6.6.4.3
<TEMPERATURE>
All limits related to temperature measurements made by both of the mounting
post PRT’s and the temperature sensor located inside the lubricating volume are
defined on this tab. Realize that the limits effect both temperature measurements,
however, only the mounting post PRT temperature is used in calculations.
The purpose of each limit is defined on the table below.
When a temperature limit is exceeded a “T” will be listed in the <Status>
category of the <Diagnostics Display>.
This forces a “Not Ready” condition.
Both change in temperature and the rate of change of temperature have
adverse effects on the load cell. For this reason, always use the FPG in
stable laboratory conditions.
