Level measurements for extreme process conditions can easily be done with the help of radiometric measurement technology. Invented by Berthold, this technology has been providing reliable measurements for more than 70 years. Gamma radiation from an externally mounted source penetrates the vessel and is attenuated by product level inside the vessel. An externally mounted detector opposite the source accurately and reliably measures the amount of gamma which passes through the vessel, and relates it to product level based on the calibration. The level value can eithe be displayed at the transmitter, or inputted directly into the PLC or process control system. Berthold specializes in providing this accurate, reliable, and contactless measurement for industries across the world.
Quality and safety
- 70 years of experience of the world market leader in radiometric level measurement technology ensure your project success
- Accurate and reliable
- No wear and tear
- Worldwide service and support
Simple and intuitive operation
- Not influenced by temperature, pressure, dust, color, conductivity or chemical properties
- Universally applicable for all vessel types, no system modification required
We customize a solution for your application and process, pairing detector length and sensitivity with the appropriate source length, activity, and shielding. We even provide sources which can be inserted into a dip pipe and shields that allow them to be locked out to allow vessel access. Let us help you find a soltuion to suit your vessel geometry, economic concerns, and accuracy requirements.
Rod source and point detector
Best technical solution with the most benefits for the user.
- Best accuracy and stability
- Linear sensitivity over the entire range
- Least influenced by NDT
- Simple spare parts stocking/handling, in case of several measurements
Rod source and rod detector
For special applications like vessels with small diameters or thick walls
- High accuracy paired with a linear sensitivity over the entire range
- Lowest source activity
- Reduced influence of gas density variations when using a dip pipe and a short detector-source distance
Fan beam point source and rod detector
Standard arrangement, usable for most applications
- Most cost efficient
- Easy installation
Point sources are widely used in many measurement tasks, including density, continuous level, or the level switch. The compact nuclear source is enclosed in a capsule, and held in a shield with a shutter mechanism. The shutter allows the gamma to be directed towards the detector while the measurement is in use, or blocks it so that the source can be locked out when the vessel or pipe must be accessed, when not in use, and for storage and transportation purposes.
A rod source entails encapsulated activity distrubed across an extended length. This can be done by winding an activated Cobalt wire (Co-60) on a carrier or placing multiple point sources (Cs-137 or Am-241) along the length. One of the benefits of a rod source is high accuracy with a simple calibration, as activity can be distributed to achieve linear count rate versus percent level.
Detectors with a small scintillator are called point detectors. They often employ a short cylinder as scintillator, e.g. 50 mm diameter and 50 mm in length. They are typically used for density and level switch applications but can also be used for continuous level measurements. Depending on the measurement task and required sensitivity, other scintillator sizes may be used. Due to the small sensitive area, point detectors are not greatly affected by background radiation. Additionally, point detectors can be easily equipped with a lead collimator to further suppress background radiation.
To measure gamma across a long vertical stretch, rod detectors with 500 mm to 8000 mm long scintillators can be used. For a level measurement, either the source or detector must cover the desired measuring range. The most cost effective arrangement is to have a fan beam point source and rod detector. For higher accuracy or sensitivy the rod detector can be paird with a rod source. As rod detectors are typically not shielded by a collimator, they are more sensitive to changes in natural background radiation and NDT.
Whitepaper "Radiometric Measurements"
Accuracy, repeatability and errors
A whitepaper explaining how radiometric measurements work and the components, as well as how they can be optimized for the highest accuracy and reproducibility. The paper explains best practices and how proper design minimizes error.
Berthold published the whitepaper “Radiation Interference Discrimination (RID) – Managing Interference Radiation in Radiometric Level Measurements”, identifying and explaining the common sources of interference radiation and their effects on nucleonic measurements. The paper elaborates on how Berthold, with its highly sophisticated radiation interference detection (RID) feature, helps plant operators maintain a reliable and repeatable measurement.
Whitepaper “Rod source / point detector"
Berthold has published the whitepaper “Rod source / point detector arrangement”, wherein the advantages and benefits of a rod source/point detector arrangement are explained. Due to less frequent production downtimes, simpler and thus more economical spare parts inventory, increased long-term and temperature stability and consistent process quality, the higher acquisition costs are mitigated within a short period of time.
Do you need help selecting the level measurement system that best fits your industry and application?
Contact our worldwide network of engineers and service technicians for expert advice and support from initial inquiry through installation and eventual source reclamation.