Level

Resources for learning about level sensors

References for you on the web. What you need to know is just a click away.

Beginners Guide To DP Level Transmitters

This is the top-rated item on ControlGlobal.com, with more hits than any other piece we’ve ever done.  In it process control consultant Dave Spitzer walks you through the basics of differential pressure transmitters: how they work, their limitations, the basic formulas needed, when and when not to use the technique. Find the complete story here.
ControlGlobal

8 Shades Of Level Sensing

This PDF walks readers through the eight most common methods of level sensing, briefly describing the advantages and disadvantages of each, their appropriate uses, economic considerations and some cautionary advice. It also includes a table outlining the appropriate type of sensor for measuring level of a variety of materials. The PDF is free and no registration is required. You can go to the direct link here. 
Sick

Capacitive Sensors For Tough Level Measurement

This brief white paper explains the science of capacitive level sensors and why they work well in applications where measuring level is particularly difficult. You can find the direct link to the document here. Scroll down the page to find the specific tutorial.
Turck

Non-Contacting Radar Level Sensors

This tutorial covers the differenced between radar and ultrasonic level sensing and those between guided-wave radar and non-contacting wave radar sensors. It also discusses appropriate applications for radar level sensors, their limitations, advantages and disadvantages and more. Go here for the complete tutorial.
Digi-Key Electronics

Big Book Of Level Measurement

An online version of Omega Engineering’s, Transactions, Vol. 4—Flow and Level Measurement, this site covers level measurement fundamentals: pressure/density level instrumentation, FG/capacitance level instrumentation, radar and microwave instruments, ultrasonic and nuclear level gauges, level switches and more. There is also a list of additional resources and a glossary of terms. Find the free, direct link here. No registration required.
Omega

Capacitive Liquid Level Sensors—The Movie

This 4.5-minute video explains what capacitors are, how they work, how they sense liquid level and how they are calibrated. It also names a number of the applications for which they can be used. The same YouTube site contains a number of other videos about level sensing and its applications. The direct link is here.
Gill Sensors

The Shrink-Swell Phenomenon

Not a problem with your diet. The shrink-swell phenomenon in the liquid level of boilers and steam generators can dramatically limit control system's ability regulate level; especially during transient conditions. This is particularly true at low power rates, below the range of steam and feedwater flowmeters, where single-element controls must function. Read this analysis of the problem by Process Automation Hall of Famer Greg Shinskey and the specific solution implemented at a nuclear power plant.
ControlGlobal

Escape The Rathole

Measuring the level of liquids is challenging enough. Solids level measurement presents a whole other set of complications. This Control article deals with the issues encountered when measuring bulk solids—clumping, ratholes, figuring the angle of repose and more. Read “Lumps, clumps and ratholes, oh my!”
ControlGlobal