STX Signal Transmitter Installation and Operation ... - Kistler-Morse

Chapter 7. MVS-STX Calibration Menu
3. Press the Menu Key to display the Main
Menu. The display shows:
MAIN MENU
F1 F2 F3
4. Press the F3 Key to access the Cal
Menu. The display shows:
CALIBRATION MENU
5. Press the F1 Key to access the Auto
Menu. The display shows:
AUTO CAL MENU
F1 F2 F3
6. Press the F1 Key to access LoSpan. The
display looks like this:
LO SPAN AUTO CAL
(Units are consistent with Units Menu.)
7. Use the keypad or Arrow Keys to input a
value that represents the estimated
quantity of material in the vessel. Press
the Enter Key. The display acknowledges
the entry and returns to:
AUTO CAL MENU
Note
Disp I/O Cal
Auto
LoSpan
LoSpan
Manual
F1 F2 F3
HiSpan
> 0 lbs
F1 F2 F3
HiSpan
F1 F2 F3
If the filling process takes a long time
and you need to use the MVS to
monitor vessel contents during filling,
enter ScfCnt, ScfWgt, and then
Zero_Cal now. (If you do not, disregard
channel monitoring data until you
complete the Auto Calibration in
Steps 8 through 10.) Complete the
Auto calibration as described below.
8. Add a known quantity of material,
representing at least 25% of the vessel’s
total capacity, to the vessel.
9. Press the F3 Key to access HiSpan. The
display looks like this:
HI SPAN AUTO CAL
> 9999 lbs
F1 F2 F3
(Units are consistent with Units Menu.)
10. Using the keypad or Arrow Keys, input
the value equal to the sum of the known
quantity (Step 8) and the estimated
quantity (Step 7). Press the Enter Key.
The display acknowledges the entry and
returns to:
AUTO CAL MENU
LoSpan
HiSpan
F1 F2 F3
11. Press the Esc Key to scroll up the menu
tree or press the Auto/Man Key to return
to channel monitoring.
Note
Shifting from the dashed to the solid
line in Figure 7-3 is accomplished by
setting zero when the vessel contains
a known quantity of material (usually
none) at a later date. The procedure is
described in Refining the Calibration
by Setting Zero in this section.
Calibration by Subtracting a
Known Quantity of Material
This calibration method does not require the
vessel to be empty. This method of calibration
is appropriate when it is easier to remove
material from the vessel than to add it. The
principle behind the calibration follows.
A value estimated to be the quantity of
material in the vessel is entered as the
Hi Span weight [point (2) in Figure 7-3].
A known quantity of material, representing at
least 25% of the vessel’s total capacity, is
removed from the vessel. The estimated
Hi Span weight minus the known quantity
that is removed is entered as the Lo Span
weight [point (1) in Figure 7-3]. The MVS
saves in memory the Lo Span and Hi Span
weights as well as the digital counts associated
with each weight. These values define
the dashed straight line and the calculated
zero counts shown in Figure 7-3. The slope of
the line is called the Scale Factor, which is
calculated internally.
The slope of the line is reasonably accurate,
because it is calculated based on the known
difference between the Lo Span and Hi Span
weights and counts. However, if the estimated
Hi Span weight is incorrect, the actual
‘location’ of the line is incorrect, resulting in
7-4