Principles for selecting weighing instruments

Load cells andPrinciples for instrument selection:

1. Measurement parameters related to scales in the selection of electronic scale sensors and instruments

1.1 The selection should be based on the main parameters of the weighing instrument: maximum weighing capacity, minimum weighing capacity, accuracy level, maximum calibration graduation n, working temperature range, static load of the carrier, peeling weight, etc.

2. Selection of weighing sensors

2.1 The accuracy level and temperature range of the weighing sensor, as well as the humidity and thermal stability and creep indicators, must meet the requirements of the weighing instrument.

If the error distribution coefficient of the weighing sensor is not specified in the design of the weighing system, the error distribution coefficient of the weighing sensor can be 0.3-0.8

If the operating temperature range of the weighing sensor is not specified in the design plan of the weighing system, the lower limit of the temperature range is -10

The upper limit of the temperature range is 40 degrees. According to the design scheme of the weighing system, the temperature range can also be limited, but the working temperature range should not be less than 30 degrees.

The maximum weighing capacity Emax of the weighing sensor should meet the following conditions:

(1) Correction coefficient for maximum weighing capacity of the weighing instrument;

(2) The maximum weighing capacity of the weighing device;

(3) Scaling of the load transfer device of the weighing machine;

(4) The number of support points for the weighing sensor.

2.5 Minimum Static Load of Sensors: The minimum load generated by the electronic scale carrier must be equal to or greater than the minimum static load Emin of the weighing sensor

The maximum graduation of the weighing sensor should not be less than the calibration graduation of the weighing instrument

2.7 The minimum calibration graduation value of the weighing sensor should not be greater than the calibration graduation value e of the weighing device multiplied by the scale R of the load transfer device, and then divided by the square root of the number of weighing sensors n. For multiple weighing range weighing devices, when the same sensor is used in more than one weighing range, or for multiple calibration value weighing devices, e should be replaced by el.

2.8 Rated output of the sensor. After loading the sensor with Emax, the change in output signal corresponding to the input voltage is generally expressed in mV/V.

2.9 The total rated value of a set of sensors should be equal to or slightly greater than the sum of the maximum range and tare weight. When ordering weighing sensors, it is necessary to specify the maximum range, tare weight, number of sensors required, and loading method for pulling or pressing.

3. Selection of weighing instruments for electronic scales

3.1 Accuracy level: The accuracy level of the weighing instrument, including temperature range and humidity stability indicators, must meet the requirements of the weighing instrument. If the temperature range is wide enough and the stability index of humidity and heat can only meet the requirements of lower accuracy levels.

3.2 Maximum allowable error coefficient of weighing instruments

If the maximum allowable error coefficient of the weighing instrument is not specified in the design of the weighing system, the coefficient can be between 1 and 0.8.

3.3 Operating temperature range

If the temperature range of the weighing instrument is not specified in the design of the weighing system, the lower limit of the temperature range Tmin=-10 degrees, and the upper limit of the temperature range Tmax=40 degrees. According to the design requirements of the weighing system, the temperature range can be limited, but the working temperature range should not be less than 30 degrees.

3.4 Maximum Calibration Divisions For each weighing instrument, the maximum calibration divisions should not be less than the calibration divisions of the weighing instrument. For multi weighing range or multi index value weighing instruments, this requirement applies to any individual weighing range or local weighing range. If it can be used for multi weighing range or multi index value weighing instruments, these functions must be included in the calibrated weighing instrument.

4. The selection of connecting cables for electronic scales The additional cables between the weighing instrument and the sensor or sensor junction box (using a six wire weighing instrument should have sensor feedback compensation function) must be selected according to the requirements specified in the weighing instrument manual.