Accuracy, repeatability and errors RADIOMETRIC MEASUREMENTS

Radiation sources Radiometric measurements for industrial processes have been around for several decades. They are an important component in the performance of critical level, density and flow measurements. Nuclear measurement gauges work where conventional measuring technology fails. They offer outstanding measurement results under extreme conditions. High temperatures, pressures and other difficult ambient and process conditions are no problem for radiometric measurements. Typical measurement tasks are non-contact level and density measurements in various vessels, bunkers and piping systems,...

Point sources Point sources are widely used in literally any measurement task, whether it is density, level or the use as limit switch. They usually comprise an inner source capsule, which securely encapsulates the radioactive material and a shield with a shutter mechanism to block the radiation in a controlled way. Fig.4 shows schematically how a detector works. When the emitted gamma quants hit the crystal, after having passed through the walls of the vessel, pipe and the measured product itself, each gamma photon in the beam might generate a light flash, resulting in thousands of subsequent...

Types of errors On the following pages we want to elucidate different types of errors that occur in a radiometric measurement. Clearly, everybody will immediately think of the statistical error, but we will show that there are other influences that create errors as well. Measurement errors can be classified into systematic errors and statistical (random) errors. A proper measurement setup delivers a good result with an appropriate accuracy and reproducibility. Often, by all means within acceptable tolerances, this is more important than the absolute accuracy of the value. If you want to watch...

Calibration Nuclear gauges work on the principal of attenuation. Basically, every matter interacts with ɣ-radiation and has an attenuating effect. Under process control perspective, this is not only the media to be measured, it is also the steel walls of the vessel, any inside construction, insulation, framework, etc. For example, a typical Delayed Coking Unit in a refinery is made of steel with a 20-50 mm wall thickness and has a diameter of 5-9 m, all packed in insulation. Thus, it is obvious that a level system needs to be calibrated onsite to reflect the non-process related attenuation. Hence,...

Application types Level switch A level switch is a point-to-point measurement, utilizing a point source and a point detector. Density Similar to the nuclear limit switch, density measurements are typically point-to-point measurements, with the same error modes. Fig.9 Level switch schematic Fig.10 Schematic of a density measurement Systematic errors can be reduced very well, by applying good workmanship during installation and setup of the measurement. This includes establishing the system with properly calculated switching limits. The most important and dominant error of a nuclear limit switch,...

Berthold Technologies stands for excellent know-how, high quality and reliability. The customer is always the focus of our solution. We know our business! Using our varied product portfolio, our enormous specialized knowledge and extensive experience, we develop suitable solutions together with our customers for new, individual measurement tasks in a wide variety of industries and applications. Berthold Technologies is specialised in radiometric process measurements for 70 years. This is our core competence with state-of-the-art and cutting edge products and solutions covering a vast range of...