Level Sensors  Basically level sensors are used to measure as well as detect the level of liquids or liquids. And level sensor is divided into several categories some commonly used level sensors are reflex level sensor, tank level sensor, bi-color level sensor, transparent level sensor. What are the applications of level sensors?   Commonly level sensors are used in many industries  Beverage and food manufacturing plants  Oil production plants  Pharmaceutical industry  Paper and Pulp Manufacturing Industry  Power Generating Plants  Petrochemical industry  Chemical industry  Water treatment plant  Waste Material Handling Industry

  Level Measurement Accurate continuous measurement of volume of fluid in containers has always been a challenge to industry. This is even more so in the nuclear station environment where the fluid could be acidic/caustic or under very high pressure/temperature. We will now examine the measurement of fluid level in vessels and the effect of temperature and pressure on this measurement. We will also consider the operating environment on the measurement and the possible modes of device failure. Level Measurement Basics Very simple systems employ external sight glasses or tubes to view the height and hence the volume of the fluid. Others utilize floats connected to variable potentiometers or rheostats that will change the resistance according to the amount of motion of the float. This signal is then input to transmitters that send a signal to an instrument calibrated to  read out the height or volume. In this module, we will examine the more challenging situations that require inferential

  Three Valve Manifold  A three-valve manifold is a device that is used to ensure that the capsule will not be over-ranged. It also allows isolation of the transmitter from the process loop. It consists of two block valves - high pressure and low- pressure block valve and an equalizing valve. Below Figure shows a three valve manifold arrangement. During normal operation, the equalizing valve is closed and the two block valves are open. When the transmitter is put into or removed from service, the valves must be operated in such a manner that very high pressure is never applied to only one side of the DP capsule. Operational Sequences of Three-Valve Manifold Valving Transmitter into Service  To valve a DP transmitter into service an operator would perform the following steps: Check all valves closed.  Open the equalizing valve ñ this ensures that the same pressure will be applied to both sides of the transmitter, i.e., zero differential pressure.  Open the High Pressure block valve slow

Level Measurement Basics  Very simple systems employ external sight glasses or tubes to view the height and hence the volume of the fluid. Others utilize floats connected to variable potentiometers or rheostats that will change the resistance according to the amount of motion of the float. This signal is then inputted to transmitters that send a signal to an instrument calibrated to read out the height or volume.  In this module, we will examine the more challenging situations that require inferential level measurement. This technique obtains a level indication indirectly by monitoring the pressure exerted by the height of the liquid in the vessel.  The pressure at the base of a vessel containing liquid is directly proportional to the height of the liquid in the vessel. This is termed hydrostatic pressure. As the level in the vessel rises, the pressure exerted by the liquid at the base of the vessel will increase linearly. Mathematically, we have:  P = S.H where  P = Pressure (Pa)  S =