Pancake load cells are on the level

The PR 6251 pancake load cell is an ultra-flat load cell, ideal for level-by-weight applications.

Every year there are around 10,000 new tank and vessel level control installations in Europe.

Typically used to measure both liquids and solids, the majority of applications are required to measure mass rather than volume.

Many solutions for accurate level control have become available over the years, but the results from these solutions vary greatly, dependent on the nature of both the application and also the material being measured.

For liquid measurement, hydrostatic methods and floats are commonly used.

Ultrasonic and radar methods are used commonly for both solids and liquids.

For continuous level measurement, ultrasonic sensors and more recently radar technology are widely used, where probes and sensors are fitted within or outside the tank and a pulse is emitted.

The time the pulse takes to reflect back to the sender is measured and the level can therefore be calculated.

The main problem with these types of solution is the reliance on height measurement.

There are several common situations where height measurement will not provide accurate level control, for example in a silo where material sticks to the edges of the tank, or when liquids are subject to foaming or evaporation.

The one method that provides a measuring principle totally independent of the material being measured is level-by-weight technology.

Level-by-weight became possible with the introduction of "pancake" load cells - low-profile load cells which become an integral part of the leg of the tank or vessel.

The nonintrusive level-by-weight principle means that issues such as the use of stirrers, foaming, evaporation, pressure surges and uneven levels of solid products become irrelevant, as the load cell measures mass as opposed to height.

There are also functional advantages with extremely simple installation and retrofitting to existing tanks or vessels, and significant cost advantages over other methods.

Pancake applications typically offer system accuracy within 0.5 to 2% dependent on the application, material and tank construction.

There are some applications to which level-by-weight is not suited, for example in a skirted silo or concrete bunker.

In these situations it is widely accepted that radar systems offers the most accurate measurement.

However in standard tank and vessel applications level-by-weight appears to be the one solution that caters for all materials.

The PR 6251 pancake load cell from Sartorius is an ultra-flat load cell, ideal for level-by-weight applications.

Supplied with a wide array of mounting accessories, the PR 6251 can be easily retrofitted to almost any tank or vessel.

For three legged tanks or vessels only one load cell is required, giving an excellent cost to performance ratio.

Hermetically sealed to IP68, the PR 6251 is built to withstand the toughest conditions.

At just 25-35mm high, the pancake load cells can easily be fitted in applications where space is limited.

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