Wireless simultaneous measurement system for liquid level and density using dynamic bubbler technique: Application to KNO3 molten salts

This paper describes a novel level sensor that is noninvasive to nonmetallic tanks and noncontact to materials stored in them. It detects the materials from the outside of a tank by the use of microwave Doppler modules. The output AC component of Doppler modules has been used as moving object detectors. Here, we focus on the output DC component, which is proportional to the intensity of the reflected microwave signals from the stored material. We propose a sensor to detect the level of very low dielectric materials. We build a theoretical model based on multiple reflections of microwaves from the surfaces between different dielectric materials and demonstrate the sensor’s theoretical potential. Experiments were carried out using the sensor to verify its feasibility. The sensor detected levels of Styrene foam with dielectric constant 1.02 from the outside of a 3.0 mm thick acrylic resin tank under optimal conditions. Furthermore, the S/N ratio of the Styrene foam measurement was over 19 dB for the drift noise caused by the change in environmental temperature from 20 °C to 80 °C. The S/N ratio of the change in tap-water’s temperature ranging from 0.5 °C to 77 °C was 18 dB at the reference of 23 °C, and for the change in conductivity ranging from 0.35 to 26 mS/cm was 33 dB.

Level Detection of Materials in Nonmetallic Tank by the DC Component of a Microwave Doppler Module

Design and development of submersible hydrostatic level sensor using a GMR sensor

The early detection of safety critical conditions of oil levels in legacy industrial or commercial hydraulic machinery is becoming a new requirement for cloud-based maintenance service and Smart Grid systems. Building communities integrate accurate smart sensors to enable near or real-time monitoring. The nonideal conditions of oil levels can lead to disastrous costly events. However, legacy systems have gone expensive rigorous safety qualifications, to alter them makes the integration of new IoT monitors a difficult decision. To avoid or mitigate safety related recertification, two test setups are proposed to determine the sensor accuracy: (1) Full-range liquid height level test at room temperature and (2) Limited-range height level test at varying temperatures to characterize its nonlinearity effects on the sensor accuracy. During the empirical testing to obtain an optimal solution, the study proposes the use of Design for Six Sigma (DFSS) statistical method, an industry best-practice methodology to minimize parametric variations -by design- and increase the accuracy through measurements of variability and central tendency. Initially, the measured data drifted more than 50 percent from the desired values for both temperature and height readings. After the optimization, the temperature performance improved to a tighter specification of 0.25 percent from the initial prerequisite of 5 percent while the height performance improved from 8 percent starting requirement to 5 percent optimal specification. The DFSS empirical test is an effective method to achieve repeatable highly accurate oil level monitor.

Non-Invasive Wireless IoT Oil Level Monitor Node using Submersible Sensors for Early Leak Detection

In this paper, a wired and wireless transmitter for two different designs of hall effect-based pressure sensors are designed and experimentally tested. A wired transmitter is designed by converting the actual sensor output to a 1-5V range using a signal conditioning circuit, followed by a voltage-to-current (V-I) converter to convert the signal conditioning circuit output to a 4-20 mA current signal which can be transmitted to any remote indicator without any data loss. A wireless transmitter is also designed with the same signal conditioning circuit and a Wi-Fi module to transmit the pressure sensor data wirelessly to the IoT cloud server. The Blynk IoT console is used as a server to access the transmitted data through a PC/laptop connected to the Internet. The linearity as % deviation and % error of the V-I converter is calculated for wired transmission and the mismatch between transmitted and received data is also found for the wireless transmission for both sensor designs. The proposed transmitters are of low cost, and simple in design, and the pressure sensor data can be transmitted in real-time using both wired and wireless modes. 

S. Faizan Ali

Papers

Design and development of an electronic level transmitter based on hydrostatic principle