Liquid level transducer
- 2. Contents Introduction Classification of liquid level measurement Types of measurement Advantage Disadvantage Applications
- 3. Introduction • Liquid level sensors are termed as the sensors used for detecting liquid levels or interfaces between liquids such as water and oil or solids and liquids. • This type of liquid level sensor is one of the most important sensors and plays a vital role in variety of industrial and consumer applications.
- 4. Liquid Level Transducer (1) Point Level transducer (2)Continuous Level transducer
- 5. (1)Point Level Transducer Point level measurement sensors are used for the purpose of marking a single liquid height or for presetting a level condition. Usually, this sensor works as a high alarm that measures the overflow conditions in tanks through liquid level sensors, or works as a marker to note down the low alarm conditions. The different types of sensors are given below: • Float Sensors • Capacitance Sensors • Conductivity Probes
- 6. (a) Measurement by Using a Float Sensor A level measurement float system consists of a float, a sensor stem, a magnet, a reed switch and a weight suspended on the outside of the open tank. A scale is fixed on the outside of the tank, and the contents of the tank’s level are indicated by the position of the weight along the scale.
- 7. (b) Measurement by Using Capacitance Sensor The measurement of liquid level is done by applying a Radio Frequency signal between the conductive probe and the vessel wall. The Radio Frequency signal results in a very-low current which flows through the dielectric process material in the tank from the probe to the vessel wall.
- 8. (c) Level Detection by Using Conductivity Probes This system is applicable for level measurement in conductive liquids. The conductivity of the insulated material can be varied if the probe is covered or not covered within the conductive product. There are two electrodes: one is used as a metal wall of the tank, and the other electrode is inserted into the tank.
- 9. (2) Continuous Level Measurement A continuous level sensor is most sophisticated and also provides liquid level monitoring of an entire system. This liquid level sensor is used to measure the fluid level within a specified range, moderately than at a one point, which produces an analog output and directly correlates to the level in the vessel. These are of three types:- Ultrasonic Sensor Radar level sensor Optical Sensor
- 10. (a) Measurement by Using Ultrasonic Sensor This liquid level sensor comprises two elements such as an associated electronic transceiver and a transducer with relatively high efficiency. In case of a liquid level controller, the fluid level can be determined by measuring the trip time difference between a transmitted ultrasonic pulse and a reflected echo.
- 11. (b) Measurement by Using Radar Level Sensor Radar level measurement system is based on the principle of measuring the time required for the microwave pulse and its reflected echo to make a complete return trip between the non-contacting transducer and the sensed liquid level.
- 12. (c) Measurement by Using Optical Sensors The optical sensor consists of an infrared LED and a light receiver. The light emitted from the LED is directed towards a prism which forms the tip of the level sensor. If there is no liquid present in the tank, then the light from the LED is reflected within the prism and the receiver.
- 13. Advantage Timely detected the amount of liquid Sense the minimization or maximization of liquid Little maintenance Cheap and power saver Non- contact Disadvantage Sometimes not accurate Careful handling
- 14. Daily life applications In Cars Fuel, oil and also in power steering fluid. Industry Storage tanks Transport tanks For sensing liquids Household Coffee automated machines Washing machine
- 15. Water Level Indicator Alarm