Key points
The cost of high-end sensors can be negligible in comparison with the processes and assets that they help to manage and protect. It is logical, therefore, for process managers to invest in measurement technologies that have been proven to deliver stable, accurate reliable measurements in the long-term.
In the following article Juhani Lehto, a Product Manager at Vaisala, explains why sensor quality is so important, providing examples of temperature and humidity measurement in industrial applications.
Choosing sensors
The results showed that this one-degree of error increased energy consumption by more than 8.5%.
There are several important factors to consider when choosing sensors. These include accuracy, stability, reliability, and the varying requirements of different applications. Stability is perhaps the most important criterion because sensors must be accurate and reliable even in demanding environments, both now and in the long-term. The specifications of different sensor suppliers may state similar accuracies, but this does not provide insights or verification of sensor accuracy after one year, or several years.
All sensors drift, but some drift a lot or quickly, while others have good stability with minimal drifting, maintaining measurement accuracy for years. Therefore, the stability of sensors should be the most important factor to consider because it influences performance and costs over a long time and is reflected in calibration and maintenance requirements.
In addition to good stability, high-quality instruments are also easy to maintain, calibrate, adjust, and fine-tune. Having convenient tools for verifying and maintaining the sensors and transmitters enhances reliability and provides peace of mind throughout the life of the instrumentation.
Small inaccuracies lead to large costs
Vaisala participated in a datacentre trial to simulate how much more energy would be used if there was just one-degree of temperature measurement error, causing excessive cooling. The results showed that this one-degree of error increased energy consumption by more than 8.5%.
Given the size of modern datacentres and assuming the same deviation can take place over a decade, this seemingly tiny error translates into many millions of euros of extra costs, particularly if server uptime is affected.
Case study: Sausage casings
A team of UK process engineers has developed a technique for manufacturing collagen sausage casings which protects product quality and trebles output. The process relies on precise monitoring of temperature and humidity, combined with multi-stage feedback control.
The manufacture of collagen sausage skins from animal hide is a good example of sustainable production because it recycles a waste product into a valuable commodity that helps to improve the quality and consistency of sausages.
However, all sausage casings are delicate and require precise conditions and careful handling during manufacture, storage and distribution, and throughout the subsequent sausage manufacturing process.
The stability of sensors should be the most important factor to consider because it influences performance and costs over a long time
Natural casings from the small intestine of meat animals tend to be variable in length, diameter and thickness, so they are not ideal for high-speed sausage manufacturing processes. In contrast, collagen casings offer reliable, consistent features, and are therefore ideal for fast, efficient processes.
Also, collagen casings do not need to be stored in chilled conditions and have a longer shelf-life than traditional casings. However, sausage casings are delicate, so precise management of handling processes and environmental conditions is essential.
Collagen casings are ready to use straight out of the package, horn loading is quick and easy, and there is no requirement for soaking and untangling of bundles. In comparison with sausages in natural casings, there are no seasonal variations, and sausages manufactured in collagen casings offer improved cooking coverage which delivers a superior cooked appearance
Previously, the sausage skin manufacturer utilised a conveyorised flat sheet collagen dryer, but this created friction that could lead to ripping and product wastage. The process was slow and wasteful, so the engineers were challenged to develop a new, less damaging technique for drying and processing the extruded cylindrical collagen cases.
A key feature of the new process would be to minimise friction and optimise both temperature and humidity, irrespective of the plant’s geographical location.
The new processing solution allows the casings to be inflated with hot, dehumidified process air provided by a silica-based desiccant rotor. New equipment was also developed for transporting the inflated gel using an innovative handling system.
Case study: Baking ovens
Climate change, environmental concerns and rising energy prices are driving demand for improved efficiency across all industries; not least in food production where processes involving baking ovens can run at temperatures of up to 325°C.
Bühler’s latest indirect-fired convection ovens, therefore aim to increase efficiency in line with the company’s strategic commitment to help customers make substantial savings in energy, water, and product wastage.
One of their customers was using natural gas at an average annual cost of €10 million before ordering the ovens, but with accurate humidity measurements a reduction in gas consumption of as much as 20% was achieved.
By monitoring humidity levels accurately inside the oven, it is possible control the process to maintain a consistent baking profile, even with fluctuations in other factors such as ambient conditions or ingredient quality. This enables a more consistent product in terms of spread, thickness, colouring, and other important quality parameters, and consistency helps to minimise wastage.
Ovens with built-in measurement technology enable process managers to control the humidity and temperature of their ovens more effectively, which can be particularly valuable for those producing multiple products with different baking profiles.
Summary
In this short article, we have highlighted the critically important role of accurate stable measurements, which highlights the need to invest in proven, high-quality sensors, particularly when the costs of not doing so can be so great.
In datacentres accurate temperature measurement can save enormous energy costs, in baking ovens accurate sensors can improve product quality, save energy and reduce wastage, and in sausage skin manufacture accurate sensors save time, reduce waste and increase productivity three-fold.
