Peek inside the pipes


Today, processes in the food and beverage industries are usually comprehensively monitored. Nevertheless, most plants have a blind spot. Operators are well informed about what’s happening in vessels and tanks, but what’s going on in the pipework? Andy Walker of ifm electronic explains how recent sensor developments make it easy to answer this important question.

Why do process plant operators in the food and beverage sectors need to know what’s going on inside their plant’s pipework? The first answer is that information such as a low flow rate or an unexpectedly empty pipe can provide early warning of developing problems, possibly in time to save expensive ingredients from going to waste. The second answer is that if the plant does develop a fault, knowledge of flow rates, temperatures, and the like is an invaluable aid to locating and remedying the cause, thereby keeping costly downtime to a minimum.

But what do the plant operators need to know? The most important parameter is the flow rate of the media in the pipe. There are, of course, many types of flow sensors, but it can still be difficult to find one that is suitable for hygienic applications, capable of consistently delivering accurate results and resistant to the rapid temperature changes and pressure surges often associated with food and beverage applications. There is, however, one sensor technology that dependably fits the bill: magnetic-inductive flow meters.

In a magnetic-inductive flow sensor, the media whose flow rate is to be measured passes through a magnetic field. As a result, a small voltage related to the speed of flow is generated in the media. The sensor accurately measures this voltage and uses it to determine the flow rate. Magnetic-inductive sensors based on this principle are not new, but the latest versions offer many advantages over their predecessors.

In the past, a significant limitation of this type of sensor was that it would only work with liquids that had a relatively high conductivity. The latest versions, however, deliver dependable results at conductivities down to just 5µS/cm, which covers the vast majority of media used in the food and beverage industry. 

The new sensors also have a high upper temperature limit of around 150 ºC, which is another important benefit in many applications, and they are highly resistant to damage. They are unaffected, for example, by rapid temperature cycling, which can be found in some cleaning and sterilisation processes. They are also impervious to pressure surges, high humidity and high levels of vibration, which might be experienced close to a large pump.

Of course, flow rate is not the only thing plant operators will want to know about what’s going on inside the pipework. The temperature of the media is also likely to be important, along with the total volume of flow, the flow direction, media conductivity and warnings if the pipe is not fully flooded. The good news is that the latest magnetic-inductive flow sensors, such as those in the SMF Foodmag range from ifm electronic, provide all this additional functionality. In many applications, this eliminates the need for additional sensors, resulting in cost savings and reductions in plant complexity.

One issue remains: how to efficiently communicate all of the information provided by these new sensors to the plant control system. The answer is IO-Link, a versatile digital connection system that ensures error-free transmission of sensor data and also supports easy-to-use options for setting up and testing the sensors.

It has been said that what’s going on inside the pipework is the last blind spot in modern process plants. With the latest magnetic-inductive flow sensors, this blind spot is finally eliminated, giving operators a truly comprehensive real-time view of everything that’s happening in their plant. Potential benefits include increased efficiency, fewer faults and reduced downtime if faults should occur. These new sensors are, without a doubt, a modest investment that can pay very big dividends.


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