May 2016, MARIETTA, GA~ COMPARISON TEST | In a study lasting more than a year, experts from SABMiller compared the Sitrans LR250 HEA radar level transmitter prototype – commercially available since September 2014 – against similar systems from other manufacturers and subjected them to thorough testing. As a result, the new transmitter satisfies the stringent requirements of EHEDG aseptic and has been accepted as part of the SABMiller standard for radar level measurement for brewing internationally.

TODAY’S BREWING INDUSTRY is characterized by a constantly growing range of varieties and bottle shapes as well as increasing cost pressure. This is leading to a growing need for hygienic, reliable and low-cost systems capable of measuring the precise content of pressurized tanks prior to filling, as well as of fermenting and storage tanks. Since this purpose was previously served mainly by ultrasonic sensors and direct contact measurements of differential pressure transmitters, Siemens developed an appropriate system based on the Sitrans LR250 radar level transmitter, which has been successful in a range of industries.

“In view of the specific requirements of the brewing industry,” says project manager Robert Gray of Siemens PI Level and Weighing in Peterborough, Ontario, Canada, “we placed particular emphasis on how to hygienically insert the probe and the variety of process connections as we were refining our proven radar level transmitter. In addition, we considered it important that the new sensor was easy to maintain and also repair in a worst-case scenario.” And the results are quite impressive: Sitrans LR250 HEA (hygienic encapsulated antenna), introduced in late September 2014, is not only much cheaper than ultrasonic-based systems offering comparable performance, but is also designed to enable replacement of the sensor’s electronics without having to disrupt the process by depressurizing and taking the tank offline. 

Comprehensive comparative study
To ensure the best possible preparation prior to introducing the new transmitter onto the market, Siemens subjected it to comprehensive testing, including a thorough comparison test performed by Instrumentation Engineering Staff Project Engineers Mr. Wade Austin and Mr. Otto Langaas of the SABMiller Group at the Chamdor Brewery in Krugersdorp, South Africa. The purpose of the study, which involved comparing the new Siemens radar level transmitter against similar systems in practical operation for more than a year, was to establish an alternative measurement method to the ultrasonic level systems and magnetic flowmeters normally used by the Group.

The first test was started on the BBT tanks. SABMiller’s requirement for this test was that the transmitter had to perform throughout the process of filling and emptying the vessel and to indicate the correct volume that was measured against the incoming flow via a magflow.

The transmitter also had to keep a stable reading on the rousing process and to ensure the reading stayed stable despite the foam that is generated during this process.

Throughout the various stages, volume is the most important measurement, as any discrepancy would generate losses between the Brewing and Packaging departments. The same function was to be mimicked on the FPT tanks but on those it was a little more difficult due the product being continuously agitated (fruit-based alcoholic beverages).

The Chamdor Brewery fitted BBT pressurized tanks and FPT beer-based drink tanks (FPT) with radar level transmitters from three manufacturers and tested them under practical operating conditions.

Figures 1 and 2 show typical test runs with tank emptying constantly or with intermediate stops comparing the new radar instrument with the existing ultrasonic solution. With an accuracy of 3 mm and a resolution of 1 mm the radar level transmitter can be used with tanks up to 20 m height as standard equipment. The process connections ranges from 2 to 8 inch with threads (DIN 11851, DIN 11864), clamps (ISO 2852, DIN 11864), flanges (ASME, DIN 11864) and Varivent.

Process Intelligence
Chamdor Brewery has a particularly broad range of products as well as the ability to test and deliver new product ranges in a very short time. Their results will transfer well to the other SABMiller sites. The Sitrans LR250 performed well on the BBT tanks with basic volume and parameter settings. It was decided to test it on the FPT tanks, as some of the other installed products were struggling in this application – again, the new radar level transmitter worked extremely well. Setting up the test unit took a bit of time in the beginning due to the tank shape (conical bottom, dome top and the nozzle that was at an angle) so the volume was not linear and had to be set on filling and emptying. Once the transmitter was reinstalled vertically, most standard settings could be used. Thanks to “Process Intelligence”, used in all Sitrans LR250s (as well as in all Siemens radar devices), the tested transmitters were able to provide an accurate measurement of the tank fill levels, even through layers of foam.

Process Intelligence is Siemens’ advanced echo processing technology for radar instruments, which provides exceptional reliability and the ability to automatically ignore obstructions. To further improve the performance of the sensors for these difficult situations, the TVT (time varying threshold) curve was further optimized by Greg Smook, Siemens PI Product Promoter and radar specialist in South Africa, during Fig. 3 The radar level transmitter is positioned in the upper part of the tank with no product contact Fig. 4 The sensors could be cleaned without difficulty at any time as part of the automatic tank cleaning process the following months and the results included in the measurement technology.

Certified in accordance with EHEDG Type EL Aseptic
The Sitrans LR250 HEA also scored well in terms of hygienic requirements: the transmitters are positioned in the upper part of the tank with no product contact; the antenna design is fully encapsulated; and the PTFEs used are particularly smooth with a surface roughness of less than 0.8 ì. As a result, the sensors could be cleaned without difficulty at any time as part of the automatic tank cleaning process. This was only one of the reasons why the radar level transmitter was certified in accordance with the stringent rules of the European Hygienic Engineering & Design Group as per EHEDG Type EL Aseptic.

Global standard for fill measurement

The new radar level transmitter has the following benefits:

• easy to install, as it fits on top of the tanks to existing process connections;

• little to no maintenance needed, as there is no drift in zero point due to production/ cleaning cycles;

• easy to access (when maintenance is needed) as the electronics can be removed without opening/emptying the tank;

• minimizes losses of time or product with synchronizing the tank emptying with the bottle feed to the filling machine.

SABMiller’s assessment after more than one year of test operations was positive: “From our perspective, the criteria that we were looking for have been satisfied. Sitrans LR250 HEA has been adopted by SABMiller as part of its Global Standard for fill measurement – both for new projects and when replacements are needed"