How to choose the weighing sensor
To choose what kind of structure form of weighing sensor mainly depends on the weighing system using the environment and the scale structure .
Weighing system operating environment
If the weighing sensor is working under high temperature environment ,it should adopt high temperature resistant sensors, especially harsh occasions must be added with heat insulation, water cooling or air cooling devices.If use in alpine regions, consider using sensors with heating devices.he sensor working in high temperature environment should adopt high temperature resistant sensors, especially harsh occasions must be added with heat insulation, water cooling or air cooling devices
Effects of dust, humidity, and corrosion
Stainless steel series products are suitable for environmental humidity > 80%RH above, and other acid, ammonia corrosion; Glue sealing series alloy steel products are suitable for environmental humidity < 65%RH with no water infiltration, no other corrosive gas, liquid.The welding sealing series alloy steel products are suitable for ambient humidity < 80%RH, with smooth drainage, no other corrosive gas, liquid.Aluminum alloy series products are suitable for environmental humidity < 65%RH.No water infiltration, no other corrosive gas, liquid
In elevated weighing systems, safety and overload protection should be considered
The explosion-proof sensors or intrinsically-safe sensors must be selected if use in flammable and explosive environments. The sealing cover of explosion-proof sensors should not only consider its airtightness, but also consider the explosion-proof strength, as well as the waterproof, moisture-proof and explosion-proof of cable leads etc.
The scale platform structure characteristics requirements
1.Installation space of the bearer. In some places with space limitation, space limitation should be considered when selecting the weighing sensor.
2.Easy to install and maintain. Regardless of the reliability of any equipment, it is necessary to consider the problem of installation and maintenance. In addition to the convenience of installation, it is also necessary to consider whether the maintenance is convenient in use and whether the weighing sensor is convenient to replace.
3.The effect of lateral forces. When selecting the weight sensor, it is necessary to consider whether the scale platform has lateral force in use. The weight sensor designed according to the shear stress principle has a strong ability to resist lateral force, while the weight sensor designed with the normal stress principle has a weak ability to resist lateral force
4. Stiffness problems of load bearers, infrastructure and accessories. The stiffness of these structures will directly affect the amount of deformation and thus affect the accuracy of measurement.
5.Influence of temperature on scale platform. For outdoor weighing systems with long bearing devices and large area, such as truck scale and large material tank, the expansion coefficient of the bearing device must be considered.
Select the number of weighing sensors
The choice of the number of weighing sensors is based on the purpose of the weighing system and the number of points needed to support the scale platform (the number of points should be determined according to the principle that the geometric center of gravity of the scale and the actual center of gravity coincide). In general, the scale platform has a few support points on the selection of a few sensors.
Weighing Sensors capacity range selection
The selction of weight sensor range can be determined according to the comprehensive evaluation of the maximum weighing value of the scale, the number of selected sensors, the weight of the scale platform the maximum possible partial load and dynamic load. Theoretically speaking, the closer the weighing value of the weighing system is to the rated capacity of the sensor, the higher the weighing accuracy will be. However, in practice, due to the existence of weight, tare weight, vibration, impact, and partial load of the scale, the principle of sensor limit selection for different weighing systems is very different.
Remarks:
When selecting the rated capacity of the sensor,its better to conform to the value of the manufacturer's standard product series as far as possible, otherwise, the selection of non-standard products, not only high ost, but also difficult to replace after damage.
In the same weighing system, it is not allowed to choose different rated capacity sensors, otherwise, the system can not work normally.
Weighing sensor accuracy level selection
Accuracy level is an important performance index of sensor, and it is an important link related to the measurement accuracy of the whole measurement system. The higher the accuracy level of the weighing sensor, the more expensive the price. Therefore, as long as the accuracy of the sensor meets the accuracy requirements of the whole measuring system, it is no need choose highest ones. The selection of sensor level must meet the following two conditions:
To meet the weighing indicator input requirement
That is, the output signal of the sensor must be greater than or equal to the input sensitivity value required by the indicator.
Follow the requirement of accuracy of the whole electronic scale
In addition to meeting the input requirements of the indicator,the weight sensor grade also needs to meet the accuracy requirements of the entire electronic scale.
Usually, an electronic scale is composed of three parts: the scale platform, the weighing sensor and the indicator. When choosing the accuracy of the weighing sensor, the accuracy of the weighing sensor should be slightly greater than the theoretical calculation value. However, because the theory is generally restricted by objective conditions, for example, the strength of the scale platform is less than that of the theoretical calculation value. The performance of the indicator is not very good, the working environment of the scale is relatively bad and so on. The reasons directly affect the accuracy of the scale, so we have to improve the requirements from all aspects, not only to consider the economic benefits, but also to ensure that the purpose of weighing.
