Magnetic Type Level Transmitters: Working Principle and Calibration

Magnetic Type Level Transmitters: Working Principle and Calibration

Introduction:

Level measurement is a vital process in various industries, such as oil and gas, chemical, and power generation. Accurate level monitoring ensures efficient and safe operations. To fulfill this need, magnetic type level transmitters have been widely employed. In this article, we will delve into the working principle and calibration procedure of magnetic type level transmitters to understand how these devices provide accurate and reliable level measurements.

Working Principle:

1. Understanding Magnetic Type Level Transmitters:

Magnetic type level transmitters are sophisticated instruments that utilize the principles of magnetism to measure the level of liquids or solids in a container. These transmitters consist of a float, a sensing stem, and a magnetic system. The sensing stem, usually made of non-magnetic material, is connected to the float and extends into the liquid or solid being monitored.

2. Magnetic Principle:

The magnetized float within the transmitter follows the level changes of the medium inside the container. As the float moves up or down according to the level variation, the magnetic system attached to the float moves with it. This movement affects the magnetic field and generates a magnetic field strength variation, which is sensed by a magnetic pickup located outside the container.

3. Magnetic Pickup and Signal Processing:

The magnetic pickup, an essential component of the magnetic type level transmitter, detects the changes in the magnetic field strength caused by the movement of the float. It converts these variations into electrical signals, which are then processed by the transmitter's circuitry. The circuitry amplifies and filters the signal to provide a continuous level output that can be displayed or transmitted to a control system.

Calibration Procedure:

1. Calibration Overview:

Proper calibration of magnetic type level transmitters is crucial to ensure accurate and reliable level measurements. The calibration procedure involves comparing the output of the transmitter to a reference standard at different known levels. This allows adjustments to be made to the transmitter's settings to achieve maximum accuracy.

2. Confirming Calibration Requirements:

Before starting the calibration process, it is essential to verify the manufacturer's specifications and requirements for the specific magnetic type level transmitter. This information includes the range, resolution, and any special considerations necessary for calibration.

3. Preparing the Testing Setup:

To calibrate the magnetic type level transmitter, it should be isolated from the process vessel and connected to a test vessel. The vessel should be filled with a reference liquid or solid material whose level is accurately measured. The reference material should cover a range of levels that spans the transmitter's measurement range.

4. Performing Calibration:

a. Zero Calibration:

Start the calibration process by adjusting the transmitter to the lowest level reference point, typically referred to as zero level. Compare the transmitter's output to the known level reference, and adjust the zero point until the indicated level matches the reference level.

b. Span Calibration:

Next, adjust the transmitter to the highest level reference point, known as the span level. Compare the transmitter's output to the known level reference and adjust the span, if necessary, to match the reference level.

5. Verification and Documentation:

After performing the calibration, it is crucial to verify the accuracy of the measurements at various other reference points within the span. This ensures that the transmitter provides accurate readings across the entire range. Record the calibration results and maintain proper documentation for future reference and auditing purposes.

Conclusion:

Magnetic type level transmitters offer a reliable solution for level measurement in various industries. Understanding their working principle and following the calibration procedure outlined here ensures accurate and trustworthy results. By properly calibrating these instruments, industries can maintain operational efficiency, enhance safety, and make informed decisions based on accurate level measurements.