Liquid Level Measurement Techniques Research Articles

Design and Development of an Electronic Level Transmitter Using Inter Digital Capacitor

A simplified economical liquid level measurement technique has been developed for measuring the level of any type of liquid. A fabricated inter digital capacitor (IDC) is used as a primary sensor that transduces the liquid head into corresponding variation in the capacitance. This variation in the capacitance changes to an electric signal, using a modified De Sauty bridge circuit. In this paper, different types of water, such as mineral water, tap water, distilled water, and river water, are used as process liquid. This sensor can be relied for the detection of the water level, independent of the water type. The theoretical analysis of the work has been illustrated in this paper to describe the working of the proposed transmitter. The proposed sensor has been developed and laboratory tested. It is found that this transmitter exhibited the linear characteristics and followed the theoretical equations. It has 12.8-mV resolutions for measurement of water level from 0 to 15 cm range.

A review on liquid level measurement techniques using mathematical models and field sensors in blast furnace

Stable blast furnace operation requires proper drainage of liquid from the hearth. The estimation of drainage rate and hearth liquid level are of utmost importance for understanding the underlying hearth phenomena. The present review gives an insight of the need for measurement of the hearth liquid level and further throws light on various methods of estimation of hearth liquid level in-depth, which is primarily divided into 2 categories namely; model-based estimation and sensor-based estimation. Although the model-based estimation and sensor-based estimation have their own advantages and disadvantages, an integrated system comprising of both methods could potentially facilitate operators to reveal the state of hearth, which is unless not available with the implementation of a single method of estimation. Furthermore, the challenges in the estimation and the prospects for determining the reliable hearth liquid level measurement in blast furnace are discussed. The article is presented to give prospect of encountering the drift occurring in estimation of liquid level, which leads to inaccurate prediction and simulation with the industrial blast furnace. Lastly, the article gives recommendation for improving the liquid level estimation methods in blast furnace.

Design and development of a level transmitter using force resistive sensor as a primary sensing element

A simple, low cost liquid level measurement technique for all types of liquids has been proposed in this study. A force resistive sensor has been used to sense the height of liquid level in a storage tank. The force resistive sensor gives the information of the height of liquid level in terms of resistance. The resistance of the sensor corresponding to the height of liquid level is converted into a voltage signal with the help of a resistance to voltage converter. The resistance-to-voltage converter output has been passed through signal conditioning circuit and voltage-to-current converter to transmit the signal to a remote location like a control room. The theoretical equations explaining the operation of the force resistive sensor for the liquid level have been derived. The whole unit has been designed, fabricated and its function has been studied experimentally. The experimental results are reported in this study. A very good linear characteristic of the proposed transmitter has been observed with very good repeatability and with a very small uncertainty of measurement.

A Liquid Level Measurement Technique Outside a Sealed Metal Container Based on Ultrasonic Impedance and Echo Energy.

The proposed method for measuring the liquid level focuses on the ultrasonic impedance and echo energy inside a metal wall, to which the sensor is attached directly, not on ultrasonic waves that penetrate the gas–liquid medium of a container. Firstly, by analyzing the sound field distribution characteristics of the sensor in a metal wall, this paper proposes the concept of an "energy circle" and discusses how to calculate echo energy under three different states in detail. Meanwhile, an ultrasonic transmitting and receiving circuit is designed to convert the echo energy inside the energy circle into its equivalent electric power. Secondly, in order to find the two critical states of the energy circle in the process of liquid level detection, a program is designed to help with calculating two critical positions automatically. Finally, the proposed method is evaluated through a series of experiments, and the experimental results indicate that the proposed method is effective and accurate in calibration of the liquid level outside a sealed metal container.

A Review on Capacitive-Type Sensor for Measurement of Height of Liquid Level

The capacitive sensors are used in a variety of industrial and automotive application. A capacitive sensor converts a change in position, or properties of dielectric material into an electrical signal. These properties of capacitor can be used to measure the liquid level in storage tanks. The various aspects and configurations of capacitive liquid level measurement have been described. Here, review is also done on the several types of liquid level measurement techniques using capacitive sensor, for conducting and non-conducting liquid.

Continuous liquid level measurement using a linear electrode array

This paper describes a novel continuous liquid level measurement technique based on a linear electrode array, which is vertically immersed in the liquid to inject an electric current into it and measure the voltage profile at different depths. We develop models that describe the relationship between voltage and liquid level for several vessel geometries of practical interest. Then, an inverse problem iterative algorithm is used to calculate the liquid level from the set of voltage measurements. The level accuracy values are far smaller than the interelectrode spacing and no calibration procedure is required. We describe a prototype measurement system to measure the water level in a 100 cm deep rectangular tank with a level accuracy of 3 mm when the electrodes are 5 cm apart.

Helium II level measurement techniques

In this paper, a survey of cryogenic liquid level measurement techniques applicable to superfluid helium (He II) is given. The survey includes both continuous and discrete measurement techniques. A number of different probes and controlling circuits for this purpose have been described in the literature. They fall into one of the following categories: capacitive liquid level gauges, superconducting wire liquid level gauges, thermodynamic (heat transfer-based) liquid level gauges, resistive gauges, ultrasound and transmission line-based level detectors. The present paper reviews these techniques and their suitability for He II service. In addition to these methods, techniques for measuring the total liquid volume and mass gauging are also discussed.

Capacitor depth gauges

In this paper, a survey of cryogenic liquid level measurement techniques applicable to superfluid helium (He II) is given. The survey includes both continuous and discrete measurement techniques. A number of different probes and controlling circuits for this purpose have been described in the literature. They fall into one of the following categories: capacitive liquid level gauges, superconducting wire liquid level gauges, thermodynamic (heat transfer-based) liquid level gauges, resistive gauges, ultrasound and transmission line-based level detectors. The present paper reviews these techniques and their suitability for He II service. In addition to these methods, techniques for measuring the total liquid volume and mass gauging are also discussed.