Salter Brecknell 7821 - Manual (Page 18)

Model 7821 Bench Scale User’s Manual 18
Gravity Mode
Warning: Using this
feature in “sealed”
applications may be
subject to approval by
the appropriate
governing agency
at the end-users site.
Gravity value roles
‘over’ at 9.8400 and
rolls ‘under’ at 9.7700.
The Gravity Mode feature provides a means of
adjusting the scale’s internal calibration factors to
compensate for variations in acceleration due to
gravity at different geographic locations. These
differences can cause a given mass to indicate a
slightly different weight at an end-user’s (local)
site than it did at the Calibration (CAL) site.
To make the adjustment, you must know the
value of the gravity constant for the local site.
This value is expressed in meters per second,
per second (i.e., m/s
2 ). It is not necessary to
calibrate the scale, therefore, no calibration
weights are needed to make this adjustment.
The scale maintains two gravity setting values.
The first is the “calibration-site” value known as
CAL-G. The second is the end-user or “local-site”
value and is known as LOC-G. When the scale
was originally calibrated at the factory, the CAL-G
and LOC-G values were both set to 9.8040 which
is the gravity constant for the manufacturing site.
To adjust the displayed weight value to accu-
rately reflect an applied test weight, you can
either recalibrate the scale or adjust the local
gravity setting.
To view the calibration or local gravity values, you
must access the DIAG menu and scroll to LOC-G
or CAL-G message and press the UNITS key.
To view or adjust the Local Gravity value, set
Switch 2 to the OPEN position. The display will
indicate the current “local” gravity value. Press
the ZERO key to increment the value or the
UNITS key to decrement the value. The gravity
value will change in steps of .0002. When the
correct value is displayed, return Switch 2 to the
CLOSED position. The scale will now use this
new relationship between calibration and local
gravity for its weight calculations.