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Design and implementation of an intrinsically safe liquid-level sensor using coaxial cable.

Jin B, Liu X, Bai Q, Wang D, Wang Y - Sensors (Basel) (2015)

Bottom Line: In this paper, an intrinsically safe liquid-level sensor system for flammable and explosive environments is designed and implemented.Additionally, the system is designed with characteristics of intrinsic safety by limiting the energy of the circuit to avoid or restrain the thermal effects and sparks.The test results demonstrate that over the measurement range of 1.0 m, the maximum nonlinearity error is 0.8% full-scale span (FSS), the maximum repeatability error is 0.5% FSS, and the maximum hysteresis error is reduced from 0.7% FSS to 0.5% FSS by applying software compensation algorithms.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Advanced Transducers and Intelligent Control Systems, Ministry of Education, Taiyuan University of Technology, No.79 Yingzexi Street, Taiyuan 030024, China. jbq_007@163.com.

ABSTRACT
Real-time detection of liquid level in complex environments has always been a knotty issue. In this paper, an intrinsically safe liquid-level sensor system for flammable and explosive environments is designed and implemented. The poly vinyl chloride (PVC) coaxial cable is chosen as the sensing element and the measuring mechanism is analyzed. Then, the capacitance-to-voltage conversion circuit is designed and the expected output signal is achieved by adopting parameter optimization. Furthermore, the experimental platform of the liquid-level sensor system is constructed, which involves the entire process of measuring, converting, filtering, processing, visualizing and communicating. Additionally, the system is designed with characteristics of intrinsic safety by limiting the energy of the circuit to avoid or restrain the thermal effects and sparks. Finally, the approach of the piecewise linearization is adopted in order to improve the measuring accuracy by matching the appropriate calibration points. The test results demonstrate that over the measurement range of 1.0 m, the maximum nonlinearity error is 0.8% full-scale span (FSS), the maximum repeatability error is 0.5% FSS, and the maximum hysteresis error is reduced from 0.7% FSS to 0.5% FSS by applying software compensation algorithms.

No MeSH data available.


(a~i) Experimental data of the measured liquid level and non-linearity obtained when we selected, respectively, nine different turning points to develop a two-section piecewise linearization; and (j) maximum non-linearity vs. turning point position.
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sensors-15-12613-f012: (a~i) Experimental data of the measured liquid level and non-linearity obtained when we selected, respectively, nine different turning points to develop a two-section piecewise linearization; and (j) maximum non-linearity vs. turning point position.

Mentions: As mentioned in Section 4.2, the output voltage of the C/V converter had roughly linear relationships with the liquid level. Therefore, the liquid level could be calculated by developing a linearized approximation. Piecewise linearization was adopted to improve the accuracy. In order to locate an optimal turning point for piecewise linearization to attain the least non-linearity error, we successively selected nine integral points ranging from 51 cm to 59 cm as turning points to develop a two-section piecewise linearization, respectively. The experimental values of measured liquid level and non-linearity error are, correspondingly, given in Figure 12a~i.


Design and implementation of an intrinsically safe liquid-level sensor using coaxial cable.

Jin B, Liu X, Bai Q, Wang D, Wang Y - Sensors (Basel) (2015)

(a~i) Experimental data of the measured liquid level and non-linearity obtained when we selected, respectively, nine different turning points to develop a two-section piecewise linearization; and (j) maximum non-linearity vs. turning point position.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507675&req=5

sensors-15-12613-f012: (a~i) Experimental data of the measured liquid level and non-linearity obtained when we selected, respectively, nine different turning points to develop a two-section piecewise linearization; and (j) maximum non-linearity vs. turning point position.
Mentions: As mentioned in Section 4.2, the output voltage of the C/V converter had roughly linear relationships with the liquid level. Therefore, the liquid level could be calculated by developing a linearized approximation. Piecewise linearization was adopted to improve the accuracy. In order to locate an optimal turning point for piecewise linearization to attain the least non-linearity error, we successively selected nine integral points ranging from 51 cm to 59 cm as turning points to develop a two-section piecewise linearization, respectively. The experimental values of measured liquid level and non-linearity error are, correspondingly, given in Figure 12a~i.

Bottom Line: In this paper, an intrinsically safe liquid-level sensor system for flammable and explosive environments is designed and implemented.Additionally, the system is designed with characteristics of intrinsic safety by limiting the energy of the circuit to avoid or restrain the thermal effects and sparks.The test results demonstrate that over the measurement range of 1.0 m, the maximum nonlinearity error is 0.8% full-scale span (FSS), the maximum repeatability error is 0.5% FSS, and the maximum hysteresis error is reduced from 0.7% FSS to 0.5% FSS by applying software compensation algorithms.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Advanced Transducers and Intelligent Control Systems, Ministry of Education, Taiyuan University of Technology, No.79 Yingzexi Street, Taiyuan 030024, China. jbq_007@163.com.

ABSTRACT
Real-time detection of liquid level in complex environments has always been a knotty issue. In this paper, an intrinsically safe liquid-level sensor system for flammable and explosive environments is designed and implemented. The poly vinyl chloride (PVC) coaxial cable is chosen as the sensing element and the measuring mechanism is analyzed. Then, the capacitance-to-voltage conversion circuit is designed and the expected output signal is achieved by adopting parameter optimization. Furthermore, the experimental platform of the liquid-level sensor system is constructed, which involves the entire process of measuring, converting, filtering, processing, visualizing and communicating. Additionally, the system is designed with characteristics of intrinsic safety by limiting the energy of the circuit to avoid or restrain the thermal effects and sparks. Finally, the approach of the piecewise linearization is adopted in order to improve the measuring accuracy by matching the appropriate calibration points. The test results demonstrate that over the measurement range of 1.0 m, the maximum nonlinearity error is 0.8% full-scale span (FSS), the maximum repeatability error is 0.5% FSS, and the maximum hysteresis error is reduced from 0.7% FSS to 0.5% FSS by applying software compensation algorithms.

No MeSH data available.