The perfect measurement solution!
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 75 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 either 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
- World market leader in radiometric level measurement technology
- 75 years of experience
- Accurate and reliable
- No wear and tear
- Worldwide service and support
Simple and intuitive operation
- Not influenced by temperature, pressure, dust, colour, conductivity or chemical product 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 / 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 / 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
Point source / 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.
In some cases, it is beneficial to have the scintillator covering a longer range, this is called a rod detector. Typically, in level measurements either source or detector span over the whole measuring range. Their length can be up to 8 m. The main benefit of a rod detector is its lower cost compared to a rod source. Albeit, the rod source would be the technologically superior system. The gamma radiation which a rod detector is able to detect, is influenced by the geometry of the radiation array. However, as rod detectors are typically not shielded (and a shield would diminish the cost advantage) they are much more sensitive for changes in natural background radiation making this effect dominant to most other errors. Particularly, taking into mind that fluctuations of ± 15 % i.e. through accumulation of Radon-222 and its decay products, e.g. after rain, are possible, which we will demonstrate later on.
Whitepaper "Radiometric Measurements"
Berthold has published the whitepaper “Radiometric Measurements – Accuracy, repeatability and errors”, wherein the radiometric measurements are explained and how your process can be performed with highest accuracy and reproducibility and the error sources can be minimized. The paper explains the nature and causes of these errors, and identifies solutions where these errors can be suppressed through the application of „best practices“ and proper design.
Whitepaper “Managing Interference Radiation in Radiometric Level Measurements”
Berthold has published the whitepaper “Radiation Interference Discrimination (RID) – Managing Interference Radiation in Radiometric Level Measurements”, wherein the common sources of interference radiation is identified and how affects nucleonic measurements is explained. The paper elaborates on how Berthold with its highly sophisticated radiation interference detection (RID) feature helps plant operators to 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.
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