Electronic weighing equipment is considered more accurate than mechanical (lever) options. The main constructive element of such weighing systems is load cell , the design of which consists of an elastic mechanical element with resistors placed on it. When a deformation occurs in the element, an electrical signal arises at the output, which is fixed on the corresponding display with interpretation in weight units.
By the type of deformation of the element, sensors are distinguished that work on:
- stretch (S-shaped);
- compression (columnar);
- bending (beam);
- twist (torsion);
- shear (also referred to as beams).
A special type is the combined type strain gauges that combine several of the above methods.
Classification of strain gauges
Requirements for the accuracy class of strain gauges are regulated by GOST 8.631-2013 (OIML R60: 2000). According to this document, strain gauges are classified into four types according to their operational capabilities: A , B , C and D . The classification is based on the concept of minimum and maximum "number of verification intervals" (SIP).
This is how the A class strain gauges are considered the most accurate, the range of the number of verification intervals is from 50,000 to infinity. Class D strain gauges are considered the least accurate, with a minimum SIP of 100 and a maximum of 1000.
Load Cell Marking
According to GOST 8.631-2013, the marking of strain gauges should contain:
- accuracy class;
- maximum number of verification intervals;
- humidity classification (if the sensor is subjected to a humidity test, the letters "SH" are applied, otherwise "NH");
- type of load (vertical arrows "up", "down" or their combinations);
- temperature range.
For example, a strain gauge cell is marked B6NH ↑ 0/50 . This indicates that the accuracy of the element corresponds to the class " B ", the maximum number of verification intervals is 6000 , the sensor has not been tested for humidity, and the operating temperature range is from 0 to 50 degrees Celsius.
