TILI Automation

 Displacer Level Transmitter 5-point calibration Question : Determine a basic 5-point (0%, 25%, 50%, 75%, and 100%) calibration table for the displacer level transmitter in this scenario: The cylindrical displacer weighs 15 pounds (dry) and has a diameter of 2 inches. The process liquid is water. The 0% process liquid level (LRV) is even with the bottom of the displacer. Assume an electronic transmitter mechanism with an output range of 4 to 20 mA. Fill the missing fields in the below table. Answer :

 Differential pressure (DP) transmitters are used to measure the interface of two fluids that have different specific gravities (S1 & S2). To make an interface measurement, the overall level must be at or above the low pressure tap at all times. It is important that the level be large enough to create a reasonable DP between the two specific gravity extremes. This measurement can be done with or without remote seals. However, from a maintenance point of view, it may be easier to use a remote seal assembly; keeping the wet leg at a constant height can be difficult in some applications. To determine the calibrated range for the transmitter, four assumptions need to be made: At the lower calibrated value, 4 mA point, the tank is filled with the lighter fluid. At the upper calibrated value, 20 mA point, the tank is filled with the heavier fluid. The taps leading to the transmitter are flooded at all times. The overall level should be equal to or higher than the upper (low pressure)...

 DP Transmitters with remote seals allow the transmitter to be removed from direct contact with the process fluid. Remote seals are useful when: 1. The process temperature is outside of the normal operating limits of the transmitter and cannot be brought into those limits with impulse piping. 2. The process is corrosive and requires frequent transmitter replacement. 3. The process requires unusual materials of construction. 4. The process contains numerous solids or is viscous; either condition could plug the impulse piping. 5. The application requires the use of sanitary connections. 6. There exists a need for easy cleaning of the process from the connections to avoid contamination between batches. 7. There exists a need to replace wet legs to reduce maintenance on applications where the wet leg is not stable or often needs to be refilled. Seals function as an extension of the transmitter. The basic measurement of level follows the same principle as pressure transmitters without s...

 To assure the safety and profitability of processes, it is essential to be equipped with instruments providing reliable and precise measurements of level. At the basics of level measurement, it is simply about determining the position of a surface inside a tank, reactor or other vessel. More precisely, level measurement is the determination of the linear vertical distance between a reference point (usually the base of a holding container) and the surface of either a liquid, the top of a solid, or the interface of two liquids. Precise control of the level of liquid in a tank, reactor, or other vessel is important in many process applications. Level measurement is often used for inventory management. To provide good control, accurate measurement is essential and several devices and systems are available for measuring product level. Each is designed to provide accurate level measurement, although measurement precision and principles of operation vary among devices. All level measurem...

An ultrasonic level transmitter is mounted on the top of the tank and transmits an ultrasonic pulse down into the tank. This pulse, travelling at the speed of sound, is reflected back to the transmitter from the liquid surface. The transmitter measures the time delay between the transmitted and received echo signal and the on-board microprocessor calculates the distance to the liquid surface using the formula. Distance = ( Speed of sound in air x time delay) / 2 Once the transmitter is programmed with the bottom reference of the application – usually the bottom of the tank – the liquid level is calculated by the microprocessor.The basic equation for calculating the tank level is Level = Tank Height – Distance   Basic Concept and Elements of the Ultrasonic Level Measurement Minimum measuring distance (Xm): (also known as the “Dead Band”) is a feature common to all ultrasonic level meters. This is a short range in front of the sensor within which the ultrasonic device can not measure...

 Definition of Level Indicator Level indicators are devices used in the measurement of level of fluids at various industrial applications. These devices are used to determine the level of liquid in tanks, drums. pressure vessels etc.. There are many level indicators to suit the needs of different applications. Normally, fluids are used in many forms in highly commercial industries. Without proper devices it will be very difficult to find the quantity and level of fluid stored. Also, in certain situations where the nature of fluid is dangerous or the place in which the liquid is stored is of such a nature that it is manually impossible to find the level, then the level indicators are of utmost importance. Depending on the type of application used, the type of level indicator should be selected. For example, in the process industry, tubular level indicators are used for better visual liquid level indication. If it is for non-contact type level measurement, then radar type indicators ...

 Capacitance Level Measurement: Capacitive level transducer is an example of indirect measurement of level Capacitance level sensors are used for wide variety of solids, aqueous and organic liquids, and slurries. The technique is frequently referred  as RF as radio frequency signals applied to the capacitance circuit. The sensors can be designed to sense material with dielectric constants as low as 1.1 (coke and fly ash) and as high as 88 (water) or more. Sludges and slurries such as dehydrated cake and sewage slurry (dielectric constant approx. 50) and liquid chemicals such as quicklime (dielectric constant approx. 90) can also be sensed. Dual-probe capacitance level sensors can also be used to sense the interface between two immiscible liquids with substantially different dielectric constants. Since capacitance level sensors are electronic devices, phase modulation and the use of higher frequencies makes the sensor suitable for applications in which dielectric constants are ...

 Level the parameters that exist in virtually every industrial process, there are many ways to measure the level, the simplest is to use the sight glass. By using a sight glass, the height of liquid in a vessel / vessel will be physically visible, so as to make the scale on sight glass, we can immediately determine what percentage of the liquid surface height of a tall vessel / tank / vessel. In the picture, a tank connected by a transparent hose using a scale of 0-100% of the total height of the tank. This level measurement principle utilizing the properties of the liquid will fill all the space that he passed on the associated vessel. Height of liquid in the tank will be the same as the height of a liquid residing on a transparent hose that serves as a sight glass. We can directly determine height (level) of liquid inside the tank by looking at the height of a liquid residing on a transparent hose (sight glass) is. However, this information can only be served directly in the fiel...

 One of the most misunderstood concepts when dealing with transmitters is zero elevation and suppression. Elevation and suppression adjustments are frequently necessary in liquid level measurement when the transmitter cannot be installed on a level with the zero level of the tank. The definition is following, but to understand elevation and suppression, its easiest if you look at it from a mathematical viewpoint, that is described in the second part of this paragraph. Zero Elevation for an elevated zero range, the amount the measure variable zero is above the lower range value. It may be expressed either in units of measured variables or in percent of span. Zero Suppression for a suppressed zero range, the amount the measured variable zero is below the lower range value. It may be expressed either in units of the measured variable, or in percent of span. Also Read: Zero Suppression & Zero Elevation Examples Mathematically you can develop equations that will let you calibrate th...

 ULTRASONIC TECHNOLOGY Ultrasonic is a non-contact level measurement method that uses sound waves to determine the process material being measured. Ultrasonic transmitters operate by sending a sound wave, generated from a piezo electric transducer, to the media being measured. The device measures the length of time it takes for the reflected sound wave to return to the transducer. A successful measurement depends on reflection from the process material in a straight line back to the transducer. However, there are various influences that affect the return signal. Factors such as dust, heavy vapors, tank obstructions, surface turbulence, foam and even surface angles can affect the returning signal. That is why the conditions that determine the characteristics of sound must be considered when using Ultrasonic measurement. Other problematic aspects of Ultrasonic transmitters to consider include: Vacuum Applications Sound must travel through a medium (usually air) The absence of air mol...