Radiometric Level Measurement

Radiometric Level Measurement

Radiometric Level measurement uses a gamma source and a detector mounted externally across a vessel; the attenuation of gamma radiation through the process material correlates to level, interface, or density depending on the configuration. Because the measurement is non-intrusive and can be performed through vessel walls, linings, and insulation, it provides continuous measurement and/or point-level detection where other technologies cannot tolerate the process conditions.

The major benefit is applicability to extreme environments: high temperature, high pressure, corrosive chemistry, abrasive slurries, heavy buildup, and complex internals that would obstruct contact or echo-based sensors. The method is largely unaffected by foam, vapor, turbulence, viscosity, or electrical properties of the medium. This makes radiometric measurement a “last-resort-but-reliable” choice for critical processes with poor measurability.

Design and deployment require compliance with radiation safety regulations, including source selection, shielding, controlled handling, and site licensing requirements. Proper engineering includes geometry review, dose calculations, mounting integrity, and ensuring that access and maintenance procedures meet safety standards. Calibration is specific to vessel geometry and operating conditions, so changes to internals or insulation can require recalibration or verification.

Applications include reactors and separators with heavy scaling, slurry tanks, evaporators, crystallizers, cokers/coke drums, and mineral processing vessels - especially where temperature and buildup are severe. Radiometric systems are also used for interface detection (e.g., oil/water) and density trending in pipelines or vessels when the installation geometry supports a stable measurement path. In solids, they can be applied to large vessels where internal access is limited and contact devices are impractical.

Integration is typically via 4–20 mA and digital interfaces, with diagnostics based on detector count rate and signal stability. High availability is supported through robust mounting, appropriate shielding design, and periodic verification aligned with regulatory requirements. When specified correctly, radiometric measurement delivers stable performance for processes that are otherwise difficult to instrument reliably.

Miller Mechanical Specialties, an exclusive authorized representative of sales and service for Endress+Hauser.