Glossary · Sensors and measurement
Point level detection
Also known as: Point level measurement, Level limit detection
German: Grenzstanderfassung
In process instrumentation, point level detection is the detection of whether a liquid or bulk solid has reached a defined height in a vessel or pipe, delivering a switching signal rather than a continuous value.
- Sensors
- Process industry
In one sentence
Point level detection signals whether a medium has reached a defined height, e.g. for overfill protection or dry-run protection of pumps.
Example
A vibrating fork switch near the top of a storage tank closes the inlet valve if the high-high level is reached.
How it applies
- Engineering: Common principles are vibrating forks, capacitive, conductive, float, optical and radiometric switches. Choose them by medium, build-up, foam and whether the switch must detect covered or uncovered state reliably.
- Safety: Overfill protection and dry-run protection are often safety or environmental protection functions. Then the switch, logic and final element form a designed Safety function, with fail-safe signal behavior and proof testing, rather than a simple process alarm.
- Maintenance: Many switches offer self-monitoring or a test function; proof tests confirm that the whole function works.
- Documentation: Document the switching point height, the switching direction (min or max safety) and the test procedure.
Point level vs. continuous level
Point level detection answers a yes or no question at one height. Continuous level measurement delivers the level across the range. A continuous value is usually not used as the only overfill protection.