Processes that take place under harsh conditions must be monitored. Monitoring is not only important for safety reasons, but also supports process optimization. Measurements of density, level or level switch play a major role in ensuring that critical processes are safer.
If you compare the available measurement technologies, you will inevitably come across radiometric measurement systems when dealing with extreme measurement conditions. For more than 70 years, Berthold provides such systems, installed worldwide, and proven under the most demanding conditions.
The principle of attenuation
Typically, a radiometric measurement system consists of two components; a source that emits gamma radiation and a detector that can detect the incident radiation. In most cases, these two components are placed on the opposite side of the geometry to be measured, such as a vessel or a pipeline. For reasons of radiation protection, the radiation source is housed in a shield made of lead, which emits the radiation only at a certain exit angle.
When the radiation reaches the sensitive detector, it is converted into an electrical signal via light flashes, which is then processed further. The measuring principle is based on a simple but ingenious concept – the principle of attenuation. The gamma radiation passes through the vessel, as well as its contents, and is then detected by the opposite detector.
Depending on the amount and density of the material to be penetrated, the radiation is attenuated to a greater or lesser extent – more material and higher density lead to more absorption. The radiation arriving at the detector is thus a measure of the attenuation and, with the use of appropriate calibration, the relevant measured value, such as density or level, can be determined.
Individuality thanks to a broad portfolio
To be able to meet a wide variety of measurement geometries and requirement, there is no one universal radiometric solution. Only through a combination of different sources and detectors is it possible to find the perfect, customized solution for each measurement task.
Depending on the application, point or rod sources can be used, various nuclides can be selected, and the activity of the sources can be individually designed. The necessary shielding for the sources is also adapted accordingly. In addition to the sources, there is also a wide variety of detectors available (Figure 2). These differ not only in their size, but also in the material or the available communication interfaces.
Due to the extensive portfolio, many different application areas can be covered where, for example, the level or density is to be determined. Berthold products are used in numerous processes in a wide variety of industries. Customers include some of the world’s biggest and best in their field – BP, Exxon Mobil, and Shell, to name a few.
Advantages of contactless technology
One of the reasons radiometry is widely used in extreme process conditions is the noncontact technology, whereby the measuring components themselves have no contact with the material being measured. Due to the external mounting installation is very simple and can also be easily retrofitted to existing vessels or pipelines.
One of the biggest advantages is that radiometry is maintenance-free and requires no recalibration. The operating costs are low compared to other technologies.
Manageable challenges
The challenges to overcome include the influence of extraneous radiation from weld testing or from a measured product that is itself radioactive. To provide reliable measurement results, various features are used.
All Berthold detectors are equipped with the XIP (X-Ray Interference Protection) external radiation detection, which prevents falsification of the measurement result. The influence due to naturally occurring radioactive substances (so-called NORM) in the measured material can be compensated by using the PRC (product radiation compensation) function.
Fluctuations in gas density in the process can also falsify the measured value, but these can be counteracted by using the GPC (gas property compensation) feature.
Support over the complete lifecycle
Where process conditions are so extreme that conventional technologies fail, it makes perfect sense to rely on radiometric measurements. Developments in plant engineering show a trend towards more and more extreme conditions.
Berthold acts responsibly throughout the life cycle of a radiometric measurement. Berthold takes care of your radiometric measurement from design to final disposal Our global network of experts is always available to provide you with fast and competent support and to find an ideal, safe, and accurate solution.
MECOSA (Pty) Ltd is the sole business partner for BERTHOLD in Southern Africa and have cooperated with Berthold for more than 35 years.
Henning Springer
MECOSA (Pty) Ltd
Tel. +27 11 257 6100
measure@mecosa.co.za
www.mecosa.co.za
