Microwave Barrier Level Measurement

Microwave Barrier Level Measurement

Microwave barrier level measurement is a non-contact switching method used primarily for point level detection in bulk solids and for detecting bulk material flow. It uses a transmitter/receiver arrangement to establish a microwave signal path; the presence or movement of material within that path changes the received signal in a predictable way. The technique is well suited to demanding solids environments, including high dust and abrasive service.

The measuring principle places a microwave transmitter and receiver on opposite sides of a vessel, chute, or conveyor (or in a suitable geometry for reflection). In an unobstructed state, the receiver detects a stable signal. When bulk solids enter the measurement path, the signal is attenuated or interrupted and the electronics generate a switching output. Where flow detection is required, evaluation methods can distinguish moving material from static build-up.

Benefits include true non-contact detection with no moving parts in the process and minimal sensitivity to extreme process conditions such as dust, pressure, and temperature. Because the signal is electromagnetic, it can remain reliable where mechanical paddles wear rapidly or where vibration-based devices face severe abrasion. The ruggedness of the concept makes it attractive for hazardous-area solids handling and for applications requiring high availability.

Applications typically include high-level alarms in silos, blockage detection in chutes, presence/absence detection on transfer points, and flow/no-flow indication on conveyors or pneumatic lines. It is frequently used in mining and minerals, cement and aggregates, plastics handling, biomass, and other industries where dust generation and abrasive particles are routine.

Proper implementation requires a clear signal path and mechanical provisions for alignment and mounting. Vessel wall material and thickness, process connections, and any microwave windows or fittings must be compatible with the installation. Attention should be paid to false trips from severe build-up in the beam path, and to selecting switching logic and response time that match the desired interlock or alarm function.

Forberg Smith, an exclusive authorized representative of sales and service for Endress+Hauser.