Test and Measurement: Know It All

Chapter 10. Strain Gauges, Load Cells, and Weighing

10.1. Introduction

Accurate measurement of weight is required in many industrial processes. There are two basic techniques in use. In the first, shown in Figure 10.1(A) and called a force balance system, the weight of the object is opposed by some known force which will equal the weight. Kitchen scales where weights are added to one pan to balance the object in the other pan use the force balance system. Industrial systems use hydraulic or pneumatic pressure to balance the load, the pressure required being directly proportional to the weight.

Figure 10.1. The two different weighing principles: (A) force balance; (B) strain.

The second, and commoner, method is called strain weighing and uses ...