Multi Phase Operation (MPO)

Key characteristics

• Robust operation under typical multiphase disturbances

• Included in all electromagnetic flowmeters with the IFC 400 converter

• Stability of operation even when gas bubbles or solid particles disrupt the media properties

• Helps avoid measurement dropouts in dynamic or challenging flow conditions

Multiphase disturbances – unavoidable or unintended?

Gas inclusions, entrained air, and solids in the medium, as well as electromagnetic disturbances may occur intentionally as part of the process or unintentionally as side effects of operations. Common causes include:

• Aeration and mixing processes

• Pump behaviour (e.g., cavitation, leakage)

• Filling, draining, or flushing operations

• Turbulence or poor flow conditioning

• Sediment, fibres, or light solids in the medium

These disturbances can change the media properties and interrupt the sensing field of electromagnetic flowmeters, making them prone to signal instability and temporary measurement failure.

How multiphase disturbances affect electromagnetic flow measurement

Conventional electromagnetic flowmeters rely on a stable, fully filled pipe with a homogeneous liquid to generate a usable measurement signal. When gas bubbles, air slugs, or solid particles pass through the measuring section, the induced voltage signal can fluctuate heavily — sometimes leading to a complete signal collapse.

Typical effects include:

• Sudden jumps in the measurement value

• Increased noise on the signal

• Temporary loss of measurement

• Device fallback into error mode

These interruptions can disrupt process control, batch operations, or continuous monitoring tasks.

To address these challenges, KROHNE has implemented advanced control algorithms in the IFC 400 converter to help maintain device operation during such disturbances.

Continuous operation under dynamic flow conditions

Multiphase flow conditions can vary widely depending on operating parameters such as pressure, velocity, viscosity, temperature, or the amount of entrained material. Even under these conditions, MPO supports continuous device operation without measurement dropouts.

While MPO does not compensate or correct measurement values, it keeps the flowmeter from stopping or entering failure mode during typical multiphase disturbances. The operator maintains visibility of the process and can continue running the plant without interruption.

Benefits

MPO provides several practical advantages for your plant and processes:

• Reduced risk of measurement failure during common gas or solids disturbances

• Improved process stability during start‑up, shutdown, flushing, or filling sequences

• Fewer unexpected standstills caused by momentary gas entrainment or solids passing through the line

• Increased robustness of electromagnetic flow measurement in real‑world conditions

• No additional hardware needed — included with the IFC 400 converter

Typical applications for electromagnetic flowmeters with MPO

Chemical industry

• Mixing and blending processes

• Reactor feed and discharge lines

• Utilities with variable or aerated liquids

Food & beverage

• Aerated products

• Cleaning cycles with fluctuating filling levels

• Liquids containing pulp, fibres, or light solids

Water & wastewater

• Pumping stations

• Raw influent and sludge transfer

• Networks with entrained air from topology or pipe conditions

Energy sector

• Cooling and utility circuits

• Condensate return with air pockets

• Flushing and fill‑drain operations

MPO is particularly beneficial where flow conditions cannot be fully controlled or where fluctuating media composition is part of daily operations.