Mass flow meters and controllers

Measuring principles

Vögtlin applies three proven measuring principles, depending on the application and required performance:

MEMS

The MEMS measuring principle is based on thermal mass flow measurement. A micro heater and two temperature sensors measure the cooling effect of the passing gas, which is directly related to the mass of the gas.
MEMS sensors measure directly in the medium, have no moving parts and are known for their long-term stability, minimal drift, compact design and low energy requirement. An internal bypass is often used to achieve different flow ranges.

Differential pressure

With the differential pressure principle, the pressure drop across a laminar flow element (LFE) is measured. Combined with a pressure and temperature sensor, the electronics calculate the actual mass flow.
This principle makes it possible to determine volumetric flow, pressure, temperature and gas density in addition to mass flow. Differential pressure meters are very flexible, accurate and suitable for both low and high flow ranges, often with one air calibration for multiple gases.

Capillary (thermal)

The capillary measuring principle is also thermal and works with a very thin metal tube through which the gas flows. The temperature change between two sensors around the capillary is a measure of the mass flow.
Capillary sensors are particularly suitable for high pressures (up to approx. 700 bar), have exclusively metal wetted parts and are therefore suitable for corrosive gases. As with MEMS, a bypass (LFE) is often used to enable different measuring ranges.

Want to know more about Vögtlin measuring principles? Download the PDF with a detailed technical explanation here.

Measuring principles explained