Rice Lake Legal For Trade Platform/Fitness Scale - Rice Lake Dietary Fitness Scale Technical and Operating Instructions - Manual (Page 21)

Dietary/Fitness Technical and Operating Instructions - Gravity Correction 17
6.0 Gravity Correction
The Rice Lake Platform Fitness Scale features a function that allows correction for gravity differences between
locations if it is used in an area different from where it was calibrated.
If you plan to use the scale in a location different from that in which it was calibrated, you will need to first
determine the gravity values, in meters per second 2 (m/s 2 ) for both the calibration location and the location the
scale will be used (point-of-use). These two values are entered into the scale during calibration and setup. If you
do not wish to use gravity correction (ie: the scale is going to be used where it was calibrated), then simply enter
the same value, such as 9.8062 for both the calibration and point of use gravity values.
NOTE: Do not enter 0 for either value.
Gravity varies from place to place on the earth and is affected most by the location’s latitude and altitude. Gravity
decreases as you move closer to the equator, and as you go higher in altitude. Several other factors, including
tidal affects, local anomalies, and buoyancy, also affect gravity’s pull on an object but to a much lesser extent.
One way to determine gravity values is to use an online service such as those provided by the National
Geophysical Data Center (www.ngdc.noaa.gov) for the US or Measurement Canada’s web site, (www.ic.gc.ca).
These sites allow you to enter latitude and longitude information and receive the estimated gravity values.
Another way is by using the following formula:
g-9.780318(1 + 0.0053024sin
2 L - 0.0000058 sin 2 2L) - .000003085H
Where: g = gravity in m/s 2
L = latitude in radians (multiply degrees by 0.0174533 to get radians)
H = altitude in meters
Once you have the gravity values, make sure they are in meters per second (m/s
2 ). For instance, if the value you
have is in milligals (such as those derived from the National Geophysical Data Center web site), you will need to
divide your value by 100,000 to get m/s 2 . Your values should be between 9.7 and 9.9 (9.8062 is the gravity value
for 45 º N Latitude at sea level).
The calibration value is entered during the calibration before placing weights on the scale. After calibration, go
into the programming mode and enter the point of use gravity value. Again, if you do not want to use gravity
correction, enter the same value in both places.
NOTE: The gravity correction function has not been evaluated by NTEP or Measurement Canada, therefore it is up to
the scale dealer to ensure the device is accurate at the intended point of use.