Kistler-Morse KM Weigh II - Manual (Page 113)

Appendix G. Calculation of Maunal Calibration Parameters
G-3
2. Calculate ‘PSI,’
A = 3.14 x diameter (ft) x 12 in./ft
x skirt thickness (in.)
= 3.14 x 12 ft x 12 in./ft x 0.187 in.
= 84.55 in.
2
PSI = 200,000 = 2365
84.55
3. EstLL = 50,000 lbs
4. MaxLL = 200,000 lbs
5. Calculate the values for the calibration:
Scale Factor Weight =MaxLL
= 200,000 lbs
Scale Factor Counts
= S x Cnts/mV x PSI ÷ 1000
= 35 mV x 699.05 Cnts/mV
x 2365 lbs ÷ 1000
= 57,864 Counts
Setting Zero = EstLL
= 50000 lbs
Direct Support Sensors
Note
In this procedure, you will need to use
the value for Cnts/mV that you
obtained from the Weigh II above.
Perform this pre-calibration after you have
placed the vessel on the supports, but while
the vessel is still empty. The calculation
of the parameters for performing a pre-
calibration follows:
1. From your direct support sensor, write
down the sensor sensitivity (S) applicable
to your sensor. The sensor sensitivity has
units of mV/Rated Load (lb). Also, write
down the Rated Load for your sensor.
2. Calculate the values for the
pre-calibration:
Scale Factor Weight = Load Cell Rated
Load x the number of legs
Scale Factor Counts
= S x Cnts/mV x Rated Load
Setting Zero = current live load = empty
vessel = 0
Note
The Scale Factor Weight and Scale
Factor Counts are input in the Manual
Menu, while the Setting Zero value is
input in the Auto Menu.
Example: You are using direct support to
monitor a vessel with four legs. The direct
support Load Stand II’s have a sensitivity of
320 mV/100,000 lbs. You have placed the
vessel on the supports, and it is empty. You
want to perform a pre-calibration. You go to
the Disply submenu in the Manual calibration
menu and write down the Cnts/mV — 699.05.
Following the procedure for pre-calibration:
1. S = 320 mV/Rated Load
Rated Load = 100,000 lbs
(both from sensor manual)
2. Calculate the values for the calibration:
Scale Factor Weight = Rated Load x the
number of legs
= 400,000 lbs
Scale Factor Counts
= S x Cnts/mV
= 320 mV
x 699.05 Cnts/mV
= 279,620 Cnts
Setting Zero = Current Live Load
= 0