JC-Sensor Training Summary

Time:2018-07-13

Date:  July 9, 2018
Place:  Naning Jiucheng Office
People: Engineer Tong, Engineer Zheng, General Yan, Dina, Toni, Joy, Cui, Chen
About: Pressure Sensors

CONTENTS:

In order to get customers’ requests better, solve customers’ problems and provide more reasonable and high-quality services, Engineer Tong and Zheng in JC company taught lessons for their 5 sales managers on Sunday, for crystal structure and working principle for sensor cores and Interpretation of transmitter parameters ,etc.

  1. The photo of sensor core’
  2. 316 stainless steel diaphragm( about 0.02mm of the thickness),force strain material, contact with the medium under test.
  3. Silicone oil filling, It is mainly used for bufferingto protect the crystal element and transfer the strain of the diaphragm.
  4. Crystal element ,carve Wheatstone bridge inside, Sensing the strain of the diaphragm,and then change Wheatstone bridge balance and output signal.
  5. Glue, glue the crystal element and glass.
  6. Glass, attach the crystal element to the glass.
  7. Air vent, connect the crystal element to the atmosphere, This pressure measurement is called pressure gauge. If it’s no air vent, it is called dead pressure.
  8. Working principle of pressure sensor : Wheatstone bridge

When the core is not under pressure, the Wheatstone bridge is in balance and output 0.

Once the core diaphragm is under external pressure, strain occurs,The dependent variable is passed to the crystal through silicon oil, break the balance of Wheatstone bridge and then output signal. The size of signal output depends on the strain degree of the diaphragm. In ordinary conditions, signal output is too weak, External amplifiers are required later,to amplify the weak signal. In addition, the form of output signal varies, such as voltage, current, 485.Hart.I2C,SPI,GPRS, MB ,etc.

  1. Working temperature and compensation temperature

Working temperature: it is the temperature during the sensor works normally.

Compensation temperature:  The sensor can maintain good performance after it is optimized to compensate the range of temperature. If it is out of the compensate temperature, the sensor can still work normally, but there is a big deviation in accuracy.

  1. The meaning of gauge pressure,absolute pressure, negative pressure.
  2. Generally speaking, the difference of gauge pressure and absolute pressure is the reference points. The gauge pressure is referenced by zero atmospheric pressure. Absolute pressure is the reference point of absolute vacuum
  3. A pressure sensor with large range, like 10MPA-70MPA, we canignore the atmosphere, so it is called absolute pressure. A sensor with measuring range 10KPA-4MPA, it can be made to gauge pressure and absolute pressure according to customers’ requirements. Negative pressure is generally customized for customers,like -100kpa~0, 0~-100kpa, -100kpa~+100kpa,etc.


The maximum negative pressure is -100KPA( absolute vacuum)

The meaning of Negative pressure range is the difference of zero output and full range output.

For example: If -100kpa is output at 0 point and 0KKA is output at FS point,

the negative pressure type is -100kpa ~0

For example:  If -100kpa as FS output and 0KKA as 0, the negative pressure

type is 0~100kpa

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