Editor's Choice


Master of all trades

February 2023 Editor's Choice Flow Measurement & Control

For many food manufacturers, raw material accounting is a highly important and frequently discussed topic. The idea behind this is to measure the exact amount of delivered raw materials, such as milk, oil or alcohol, and then precisely allocate how much is used in each of the individual production steps. The goal is to provide as much transparency as possible when it comes to the raw materials used in the production of various products – such as cheese and butter at a dairy operation – and to be able to create full cost accounting.

The Promass Q Coriolis-based flowmeter from Endress+Hauser offers food manufacturers the opportunity to optimise their raw materials accounting with innovative technology. The Promass Q is a multivariable measurement instrument that supplies users with not only common values such as mass flow, density or temperature, but also quality-relevant parameters such as overrun or brix measurement in real time to ensure optimal product quality. It is a genuine master of all trades designed to help food manufacturers with their daily challenges.

Erroneous volume and mass flow measurements

Volume and mass flow are two commonplace terms whose meanings can lead to very stark differences in materials accounting. In contrast to volume, mass flow exhibits a constant behaviour when subjected to changing influences such as pressure and temperature. Therefore, accounting systems rely on units of mass in most cases. Many companies nevertheless use volume measurements, which can lead to unwanted differences in the raw materials account settlement. But even mass flow measurements have potential sources of errors that users should consider. In the field, one of the primary causes of measurement discrepancies relates to undetected air or gas entrainment in fluids, which distorts the measurement value and leads to differences in the raw materials accounts settlement. To prevent this from occurring, customers rely on the Promass Q, a Coriolis-based flowmeter that detects gas entrainment and lowers the measurement error ratio to nearly zero.

Gas entrainment distorts values at the delivery point

Because dairy trucks are not full at the start of the run, their tanks contain a considerable amount of air. The milk constantly swishes around in the tank and mixes with the air. If volume flow is used as the measurement unit when the milk is retrieved from the farm, it leads to an exaggerated measurement, which in turn exaggerates the amount of raw milk delivered to the dairy. This is because the air has significantly increased the volume. In practice, an increase of 10 to 20% is not uncommon. Assuming the air is purged during the production process, the dairy operator ends up posting a loss when settling the raw material accounts. This also makes it difficult to create accurate full cost pricing.

Many dairies have opted to replace volume flow with mass flow to measure the amount of milk that is delivered and processed. Unfortunately, unwanted accounting differences can still occur due to air entrainment, which also influences mass flow measurements. Although the effect is lower, it still exists and can lead to deviations. When processing large quantities of raw milk, small percentage errors add up to significant sums in a year.

Multifrequency technology for reducing measurement discrepancies

To eliminate discrepancies in mass flow measurements, customers rely on the new Promass Q, which features the patented multifrequency technology. What makes it unique is that the Coriolis tube oscillates within two superimposed resonance frequencies instead of just one, a major advantage over the conventional Coriolis measurement principle. Measurement errors caused by entrained gas can be virtually eliminated. Compared to the processes available to date, the Promass Q allows food manufacturers to measure the quantity of incoming raw milk more accurately, and as a result it significantly optimises the internal raw materials settlement.

Determining overrun levels

The Promass Q multifrequency technology not only makes it possible to eliminate mass flow measurement discrepancies with fluids. It can also precisely measure the overrun in other products where various gases are infused, such as cream cheese or ice cream. In this case manufacturers strive to create an especially light and fluffy consistency.

In environments where experience served as the basis for entrained gas values and the amount of gas was adjusted after drawing samples – after all, raw milk is subject to certain fluctuations – overrun can now be measured with a high degree of accuracy. This in turn helps reduce fluctuations in the quality of the product.

The Promass Q has repeatedly demonstrated its suitability for measuring overrun. Users were able to monitor and regulate the entrained gas levels in the process by means of density measurements, thus preventing off-spec batches or fluctuations in product quality.


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