Ultrasonic level sensors

Ultrasonic level sensors measure the distance from the transducer to the surface of the medium without direct contact with the level. This group includes devices explicitly intended by the manufacturer for level measurement in tanks and silos. Always assess suitability for liquids or bulk solids according to the specific medium and version.

BALLUFF M30E2 process level sensors

The BUS M30E2 series is explicitly intended by the manufacturer for non-contact level measurement in tanks. Assess the G 1 process connection and the design of the active face together with the medium, pressure and required sealing method. The maximum range may not be identical to the recommended working range; the datasheet of the specific variant is decisive.

View BALLUFF BUS005U · Use of the M30E2 series for level according to the manufacturer.

Continuous measurement and limit level

A level meter evaluates the return of the ultrasonic echo. The level height is determined from the measured distance and the specified geometry. For continuous measurement, verify the corresponding analogue or digital output; a switching output signals that a set limit has been reached. Conversion to volume requires knowledge of the vessel shape.

Range, blind zone and location

With an empty tank, the surface must still be within range, and when full it must remain outside the blind zone. Allow a reserve for waves. Choose the sensor position with regard to walls, stiffeners, agitators and the filling stream, which can create unwanted reflections or obstruct the measuring path.

• State the medium, minimum and maximum level and the dimensions of the vessel.
• Verify the pressure, temperature, face material and process connection.
• Assess foam, condensation, deposits and air flow above the level.
• Compare the output, supply and behaviour on loss of echo.

When to carry out an application test

Foam can attenuate the ultrasonic signal; a changing environment affects sound propagation. Therefore also test filling, emptying and agitation. For bulk solids, take into account the uneven surface and the pouring cone. The degree of protection of the housing alone does not confirm chemical resistance or usability in a pressure vessel.

Can an ordinary cylindrical sensor be used for level?

In some applications yes, if it corresponds to the documentation and operating conditions. However, the mere ability to sense a liquid surface does not make an ordinary sensor a process level meter. Assess the design and the manufacturer's explicit intended use together.

All ultrasonic sensors and selection guide · Sensor Cables and Connectors

Technical documents: VEGA ultrasonic level meter technical documentation · VEGA documentation on ultrasonic level measurement.

Selection questions

How is the level height determined from the measured distance?

The level height is the difference between the known distance of the face from the reference bottom and the currently measured distance to the surface. Conversion to volume requires the vessel geometry; the highest level must remain outside the blind zone.

Do all BALLUFF M30E2 sensors provide a continuous analogue signal?

No. For example, BUS005U has two PNP switching outputs for limit states. For continuous measurement, compare the analogue variants BUS005W, BUS005Y, BUS0085 or BUS0086 and their specific range.