Optimal measuring arrangement
- Non-contact measurement - Detectors and electronics have no contact with the interior of the vessel
- Representative measurement due to high-energy gamma sources and a long measurement path in the product
- Depending on requirements, two different arrangements (aligned or staggered) are available
Reliability and safety
- Use under extreme process conditions possible
- Redundant readings - density and level
- Dose minimization - Use of low activities and safe handling of sources by using flange mounted shields. Use of low activities and sources that can be retracted into flange mounted shields
- Impervious to wall buildup
Highly sensitive scintillation detectors
Offering features such as 304 or 316 L housing materials and SIL 2/3 certification, the highly sensitive LB 480 detectors are the ideal density meters for this measurement setup. The number of detectors used depends on the measuring range and the desired resolution. For the correct positioning of the detectors on the vessel outer wall, a robust, tailor-made mounting structure is used. Due to this arrangement, the detectors and the electronics are easily accessible for assembly and are also unaffected by the process temperatures in the vessel itself. The local density values of the individual detectors can be transferred to the customer control system via a 4 ... 20 mA HART signal.
Dip tube
A dip tube (dry well) is inserted inside the vessel to position the sources correctly and prevent them contacting the vessel's contents. In order to ensure an almost identical distance between the dip tube and the container inner wall across the entire measuring range, the geometry of the dip tube is determined by the vessel orientation: a straight dip tube is used for vertical cylindrical vessels; a curved dip tube is used for horizontal cylindrical vessels. Each dip tube is custom designed and is available in different materials.
Sources
The radiation sources are encapsulated gamma sources (Cs-137), which are installed in flexible rods. The number of sources or flexible rods is determined by the measuring range and the desired measuring arrangement.
Our sources are individually designed by our project engineers for each application, to minimize activity and doserate and optimize accuracy.
Shields
Berthold supplies a flange mounted shield into which the sources and flexible rods can be withdrawn and locked out for transport, storage, and to ensure the safety of workers needing to access the vessel. The height of the shields are minimized by using multiple flexible rods, but the shield effectiveness is maintained to minimize doserate.
Transmitter LB 478
If the level of the individual phases is required, the LB 478 transmitter is connected and the staggered arrangement is the first choice. Using the density outputs, the heights of the density detectors, and algorithms, this LB 478 unit determines the exact position of the individual layers and outputs level values as 4-20 mA HART signals. Monitoring both densities and phase levels ensures redundant signal transmission. The transmitters in the control cabinet also provide a display of the phase levels.
