Apparatus for field calibration of large size liquid level sensors

Abstract

The embodiment of the invention discloses a straight-line benchmark structure for field calibration of a large-size liquid level sensor and relates to the technical field of length measurement. The straight-line benchmark structure can be used for the length measurement of the field calibration of the large-size liquid level sensor. A plumb line fixing mechanism is fixed to a flange plate, a laser reflection buoyancy target is a flat cylinder with a through hole in the center, a plumb line penetrates through the center through hole of the laser reflection buoyancy target, one end of the plumb line is connected with the plumb line fixing mechanism, and the other end of the plumb line is connected with a plumb bob. The laser reflection buoyancy target is arranged between the plumb bob and the plumb line fixing mechanism, the plumb bob is vertically hung in a tank body of a liquid storage tank and extends below the liquid surface in the liquid storage tank, and the laser reflection buoyancy target floats on the liquid surface in the liquid storage tank. The straight line benchmark structure is mainly used for the field calibration of the large-size liquid level sensor.

Description

technical field [0001] The invention relates to the technical field of length measurement, in particular to a device for on-site calibration of a large-size liquid level sensor and a distance testing method. Background technique [0002] At present, the liquid level sensor calibration methods can be divided into two categories, namely, the laboratory simulation liquid level change method and the actual liquid level change method on site. The characteristics of the on-site actual liquid level change method are: the calibration result comprehensively considers the large-scale liquid level sensor indication error, installation error, secondary instrument error, environmental error and other factors on the user's site. The result is reliable, but the calibration process is complicated. The characteristics of the laboratory simulation liquid level change method are: simple calibration steps, high calibration efficiency, no need to input the real liquid level change during calibra...

AI Technical Summary

Problems solved by technology

[0004] (1) Splicing guide rail type: The segmented linear guide rails are spliced ​​into long linear guide rails on site, and put into the tank while splicing, as a straight line reference for calibrating the liquid level sensor. It is characterized by limited splicing length and is greatly affected by the environment. Therefore have certain limitations;

[0005] (2) Steel tape type: the steel tape is used as the linear reference and length reference for calibration. It is characterized by simple installation and is suitable for the test site. However, when the ambient temperature, liquid temperature, and force change greatly, the indication error of the steel tape The change will be too large, so that the measurement uncertainty of the calibration does not meet the requirements;

[0006] (3) Non-contact type: use the ultrasonic liquid level sensor as the length reference, determine the emission direction of the ultrasonic wave by finding the minimum value, and use it as a straight line vector reference. It is characterized by easy installation and little environmental impact, but the calibration measurement is uncertain The accuracy is large, often exceeding the measurement uncertainty of the calibrated liquid level sensor, and it is only used for comparison

[0007] For the on-site calibration of large-size liquid level sensors in the tank, due to its large length measurement range, it is not suitable to use a spliced ​​guide rail type linear reference; and the on-site ambient temperature, liquid temperature, and force change are large, and it is not suitable for a steel tape type linear reference; for High-precision liquid level sensors are not suitable for non-contact linear references. In summary, there is currently no linear reference suitable for on-site calibration of large-size liquid level sensors in tanks

Images