Why Choose Level Sensors???

For purposes of position sensing applications, engineers are specifying incremental sensors as they believe absolute sensor are too costly or too complex. Understanding the main differences between absolute and incremental level sensors is very important.  This is often a great challenge for many engineers. Sometimes the terminologies dealing with position sensing is too confusing too. Some sensor manufacturers even claim to make absolute measurement sensors when in truth all they offer is incremental measurement sensors. 

What is the difference between absolute and incremental sensors?

The main distinguishing feature is that in incremental measurement level sensors, it reports incremental change in position. This means that the level sensor is powered up and does not report its position until you give it a reference point from which it bases the measurement.  On the other hand, absolute measurement level sensors reports its actual position within arrange or scale.  When it is powered up, it reports its position without any need for reference information. 

What happens on power up?

This is a good acid test that helps differentiate these two typesof level sensors. In fact, if the level sensors has to go through some calibration process, then it is an incremental level sensor. If on the other hand, it doesn’t then it is an absolute level sensor.

Levelpro 800 Series Liquid Pressure Sensor

Reliability and wear issues

As much as potentiometer are a common form of position level sensors, the use of non-contact level sensors has grown over the years significantly.  This trend is attributed to problems associated with reliability and potentiometer ear particularly in harsh environments or even extended life-times.

Potentiometers are absolute. However, the common form of non contact level sensors is optical encoder. The device works basically by shinning a light through an optical grating then calculating position based on the intensity of returned light. Many optical devices are incremental. The position information is delivered using a series of pulses mostly in quadrature phase to aid in determining the direction of travel.

In the case of absolute level sensors, the optical device uses a different scale, whereby the absolute position is determined through a power up without a need for reference mark.  These level sensors have digital output with resolutions defined by number of bits in that output.  Incremental level sensors are cheaper than absolute level sensors hence sell more. However, you need to get the most suitable level sensor for your application for reliable results.

In most cases submersible pressure sensors like the Levelpro series offer extremely long life and are suitable for aggressive chemicals .

Some of the non-contact level sensors like the Flowlinewill offer you good accuracy, improved performance and reduced overall cost.

 There are also new generation inductive devices that also offer accurate absolute position level sensors unaffected by harsh environments. These devices are laminar windings, printed and have fundamental operating principles similar to that of a resolver or transformer. The physical involved enables high resolution, compact, absolute and lightweight level sensors independent on optical features from a light source.

 The other advantage of these inductive devices is that they are not affected by foreign matter like moisture and dirt. In addition, their performance measurement are not affected by generous mounting tolerances or offsets hence do not need precision housings.

Levelpro Level Sensors offers a complete range of pressure sensors suitable for industries toughest chemicals.

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