458 research outputs found
A non-contact capacitance type level transducer for liquid characterization
The liquid properties such as buoyancy, pressure at
a depth, relative electrical permittivity, electrical
conductivity, thermal conductivity, absorption of
radiation, liquid surface reflection of sound or light
waves, are used to design the different types of liquid
level transducers for liquid level measurement in any
process industry. The contact-type level-sensing
transducers have the disadvantage that their
characteristic properties may change due to physical
or chemical reaction between the liquid and the
probing material, and hence may affect accuracy
besides their life time.
The non-contact-type level-sensing probes may
have longer life period, but they are comparatively
costly and require various environmental and
experimental precautionary measures when being
used.
In this paper, a low-cost non-contact capacitance
type liquid level measuring technique has been
designed and used for liquid identification objectives.
The results obtained are very much consistent with the
theoretical derivations
Capacitive transducer circuits for liquid level measurement
This work is making use of the capacitive element that is made of two electrodes - a column of liquid the level of which is to be measured, and a metallic tube that is pulled and fitted over a PVC tube of accordingly smaller dimensions. Both of the electrodes are provided with contact terminals for easy connection within a bridge circuit, which is powered by a sinusoidal source of given amplitude and known frequency. Precautionary measures are taken for improved linearity and minimal interference of the power supply on experimental data obtained as a result of measurement. The experimental data shows good consistency with the theoretical details and
derivations
Development of a Capacitance Sensor System to Measure Ultra-Low Water Content in Crude Oil
The capacitance sensor system had been applied in various applications including measurement of water content in crude oil. The purity of crude oil is graded based on the water content found in it. The lesser the amount of water detected, the higher the purity of crude oil. The determination of water content is crucial as it directly reflects the quality of crude oil. However, the capacitance sensor system is limited to a high water concentration measurement. In this project, a higher resolution measurement is introduced which utilizes the capacitance sensor system based on phase angle conversion. The presence of water inside the crude oil is indicated by the change in capacitance value and results in a phase shift. The sensor system is capable of detecting a very small change of capacitance, meaning it is able to measure ultra-low water content inside the crude oil
A Supply-voltage driving scheme for grounded capacitive sensor front-ends
n this article, a novel supply-voltage driving1 (SVDR) scheme for capacitive sensor front-ends is proposed to2 eliminate the parasitic capacitance effects. The suggested circuit3 is intended for remote sensors (and, hence, connected to the4 circuit through a shielded cable) with one electrode grounded5 and of low capacitance (in the 0–10-pF range). The effects of6 the parasitic capacitance of the cable are avoided using the7 active-shielding technique, whereas those of the amplifier input8 through a smart driving of the reference node of the amplifier9 supply voltage. Thanks to these techniques, the input–output10 characteristic shows, without applying any adjustment and/or11 calibration, an offset error lower than 3 fF. The nonlinearity12 error (NLE) is in the order of 0.01% of the full-scale span (FSS),13 which corresponds to 1 fF. Different operational amplifiers (OAs)14 and different lengths (up to 15 m) of the interconnecting cable15 are experimentally tested to demonstrate the feasibility of the16 circuit. In comparison with similar circuits recently suggested in17 the literature, the proposed circuit does not require any bulky18 component, such as a transformer, and consequently, it is a19 lower-cost solution and suitable to be integrated.Peer ReviewedPostprint (published version
Miniature, High Efficiency Transducers For Use IN Ultrasonic Flow Meters
This thesis is concerned with the development of a new type of miniature, high efficiency transducer for use in ultrasonic flow meters. The proposed transducer consists of a thin plate of a suitable piezoelectric material on which an inter-digital transducer is fabricated for the generation and detection of plate acoustic waves. When immersed in a fluid medium, this device can convert energy from plate acoustic waves (PAWs) into bulk acoustic waves (BAWs) and vice versa. It is shown that this mode coupling principle can be used to realize efficient transducers for use in ultrasonic flow meters. This transducer can be mounted flush with the walls of the pipe through which fluid is flowing, resulting in minimal disturbance of fluid flow. A prototype flow cell using these transducers has been designed and fabricated. The characteristics of this device have been measured over water flow rates varying from 0 to 7.5 liters per minute and found to be in good agreement with theory. Another attractive property of the new transducers is that they can be used to realize remotely read, passive, wireless flow meters. Details of methods that can be used to develop this wireless capability are described. The research carried out in this thesis has applications in several other areas such as ultrasonic nondestructive evaluation (NDE), noncontact or air coupled ultrasonics, and for developing wireless capability in a variety of other acoustic wave sensors
Development of a Capacitance Sensor System to Measure Ultra-Low Water Content in Crude Oil
The capacitance sensor system had been applied in various applications including measurement of water content in crude oil. The purity of crude oil is graded based on the water content found in it. The lesser the amount of water detected, the higher the purity of crude oil. The determination of water content is crucial as it directly reflects the quality of crude oil. However, the capacitance sensor system is limited to a high water concentration measurement. In this project, a higher resolution measurement is introduced which utilizes the capacitance sensor system based on phase angle conversion. The presence of water inside the crude oil is indicated by the change in capacitance value and results in a phase shift. The sensor system is capable of detecting a very small change of capacitance, meaning it is able to measure ultra-low water content inside the crude oil
An auto-balancing capacitance-to-pulse-width converter for capacitive sensors
A novel auto-balancing capacitance-to-pulse-
width converter (CPC) that uses sinusoidal excitation, and
operates in a closed-loop configuration, is presented in this
paper. Unlike most of the existing CPCs, the proposed
interface circuit is compatible with both single-element and
differential capacitive sensors. In addition, it provides a
pulse-width modulated (PWM) signal which can easily be
digitized using a counter. From this PWM signal, a ratio
output is derived when a single-element sensor is interfaced,
and a ratiometric output is obtained for a differential sensor.The authors would like to thank the Department of Science
and Technology (DST), Govt. of India, for its financial
assistance (Grant Number SERB/F/4573/2016-17) in carrying
out the research activities presented in this paper.Postprint (published version
Applications on Ultrasonic Wave
This book presents applications on the ultrasonic wave for material characterization and nondestructive evaluations. It could be of interest to the researchers and students who are studying on the fields of ultrasonic waves
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