Mettler Toledo LJ16 Spezifikationen PDF herunterladen (Seite 69)

METTLER TOLEDO Weigh Module Systems Handbook

(12/99)6-2

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 Bolt: This bolt connects 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 bolt and the top plate so that the bolt does not receive any of the

weight that is being transferred to the load pin. This bolt can also be used to jack up an

empty tank so that the load cells can be replaced if necessary.

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 20,000

pounds of a liquid. The tank itself weighs 10,000 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.

20,000 lb Weight of liquid

+10,000 lb Weight of empty tank

30,000 lb Total weight

x 1.25 Safety factor

37,500 lb Adjusted weight

÷ 4 Number of weigh modules

9,375 lb Weight per weigh module

Since each weigh module will need to handle up to 9,375 pounds, the best choice for

the job would be weigh modules with a capacity of 10,000 pounds each.

Selecting Material

Load cells and other weigh module components can be manufactured of carbon steel or

stainless steel. Weigh modules that will be exposed to wet or corrosive environments are

generally made of stainless steel. When selecting weigh modules, you will need to

consider the environment in which they will be used and the materials that your facility

will handle. Appendix 12 provides a chemical resistance chart to aid in selecting

materials.

1 2 ... 64 65 66 67 68 69 70 71 72 73 74 ... 197 198

Keine Kommentare

Mettler Toledo LJ16 Spezifikationen Seite 69