Practical engineering guide

Specifying tank level measurement

First decide whether the application needs level, volume, an interface between two liquids or a limit signal. The measurement principle and sensor position follow from that purpose.

The tank is part of the measurement system

Tank shape, nozzles, internals, agitators and filling arrangements influence the result. Converting level into volume requires geometry or a tank conversion table. Distance alone does not establish product quantity. Inventory monitoring may have different requirements from fast pump control or an overfill protection function.

Radar, guided probes and pressure

Non-contact radar does not require an immersed probe, but its position must account for obstructions and reflection conditions. Guided wave radar uses a probe in contact with the product, so buildup, mechanical loads and compatibility need assessment. Hydrostatic measurement evaluates liquid-column pressure; engineering must account for density changes and pressure above the liquid.

Check the complete operating cycle

Foam, condensation, low reflectivity, turbulence and rapid filling can affect the choice. No principle is best for every vessel. Engineering defines the range, position, processing, alarms and verification. Critical protective functions need their own assessment: an ordinary process reading is not, by itself, evidence of adequate overfill protection.

Expected engineering outputs

Measurement principle, instrument and mounting specification.
Agreed conversion into the required process quantity.
Verification plan for indication, alarms and interfaces.

Technical sources and further reading

Reviewed on 18 October 2026. Product limits and applicable requirements are confirmed for each specification.

Selection in context

Selecting level measurement

Tank geometry, fluid properties and process conditions drive selection; process level measurement and overfill protection need specifications appropriate to their different functions.

On a small screen, scroll the table sideways to compare the selection criteria.

Selecting level measurement
Principle or option	Typical application	What to verify when selecting
Non-contact radar	Continuous measurement of distance to the surface without an immersed probe.	Nozzle and beam alignment, internal obstructions, medium reflectivity, foam, condensation and antenna contamination.[1]
Guided-wave radar	Level measurement along a probe; liquid interfaces where media and configuration permit.	Dielectric properties of each layer, probe length and support, buildup, emulsion and measuring limitations near probe ends.[1]
Hydrostatic or differential pressure	Liquid column height inferred from pressure near the bottom of a tank.	Density and its variation, pressure above the liquid, tap elevations, fouling and temperature effects on a remote-seal assembly.[2]
Magnetic float level indicator	Local visual level indication using a float in a bypass chamber.	Fluid density for the float, pressure and temperature, chamber materials, open connections, and provisions for isolation and cleaning.[3]
Sight-glass level gauge	Direct local level viewing; a transparent design may also reveal colour or a liquid interface.	Glass and gasket design for the medium, lighting, deposits, temperature changes and safe maintenance access.[4]

Sources for this comparison

Reviewed on 18 October 2026. Selection is confirmed for the specific operating conditions and equipment design.

Before we start

Questions that shape the project.

Can radar determine volume without tank information?

Level alone is insufficient for accurate volume. A relationship between height and volume is needed, especially for horizontal or irregular tanks. Its source and accuracy belong in the specification.

Is hydrostatic measurement independent of the product?

No. Converting pressure to level depends on liquid density and the pressure reference. Changing composition, temperature or pressure above the liquid may require compensation or a different measurement principle.

Your next project

A clear brief.
A practical next step.

Send your drawings, operating parameters or a short description of the change you need. We will review the technical interfaces and propose the next steps towards a quotation, clarifying any missing information with you.

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