Specifications

METTLER TOLEDO Weigh Module Systems Handbook
(12/99)7-2
Load Pin: This pin fits into an opening in the underside of the top plate. It transfers
weight from the top plate to a single point on the load cell.
Top Plate: This plate is bolted or welded to a tank or other structure so that it receives the
weight of the tank.
Hold-Down/Jacking Bolts: These bolts connect the top plate to the base plate in order to
check any uplift forces that might cause the tank scale to tip. Clearance must be
maintained between the bolts and the top plate so that the bolts do not receive any of the
weight that is being transferred to the load pin.
Sizing Weigh Modules
To design a tank scale that will weigh its contents accurately, you must use weigh
modules with the proper load cell capacity. There are three main factors in sizing weigh
modules for a tank scale: (1) the weight of the empty tank, (2) the weight of the tank’s
contents when full, and (3) the number of weigh modules. The number of weigh
modules will equal the number of legs or supports that the tank has.
A standard safety factor of 1.25 is normally figured into the calculation to compensate
for uneven load distribution and any underestimation of weights. Certain installations
might have special environmental considerations requiring additional safety factors.
Environmental considerations are discussed in Chapter 4.
Calculating Weigh Module Size
Suppose that you want to add weigh modules to a tank designed to hold 200,000
pounds of a liquid. The tank itself weighs 100,000 pounds and stands on four legs.
Assume that only the standard safety factor is needed for this installation. To determine
what size weigh modules you will need, calculate the total weight of the tank and its
contents, figure in any safety factors, and then divide by the number of weigh modules.
200,000 lb Weight of liquid
+100,000 lb Weight of empty tank
300,000 lb Total weight
x 1.25 Safety factor
375,000 lb Adjusted weight
÷ 4 Number of weigh modules
93,750 lb Weight per weigh module
Since each weigh module will need to handle up to 93,750 pounds, the best choice for
the job would be weigh modules with a capacity of 100,000 pounds each.