We offer the widest product range of low-flow (mass) flow meters and controllers on the market. Numerous styles of both standard and bespoke instruments can be offered for applications in laboratory, machinery, industry and hazardous areas.
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Bronkhorst instruments are used for numerous applications in many different markets. In this section you will find an overview of the main markets for our equipment, illustrated with some typical examples of applications.
Are you looking for technical documentation, are you interested to learn more about the measuring principles of Bronkhorst products, or you do want to get in contact with a Bronkhorst Service Engineer? This section will guide you to the relevant service & support topics.
Bronkhorst High-Tech BV the leaders in Mass Flow Meter / Mass Flow Controller technology for gases and liquids, Pressure Controllers and Evaporation Systems.
Thermal flow instruments behave best using a laminar flow, at least if we look at the thermal mass flow meters and controllers with a bypass sensor. To conduct a precise measurement with this flow instrument, laminar flow is preferred.
However, in practice you will encounter a turbulent flow quite often. A turbulent flow can be caused by restrictions in an installation, such as valves or adapters, in combination with a high velocity of the used fluid. This effect is known as ‘turbulence effect’. A turbulent flow can affect the accuracy of your measurement, something you would like to prevent.
“Turbulence is a dangerous topic which is often at the origin of serious fights in the scientific meetings devoted to it since it represents extremely different points of view, all of which have in common their complexity, as well as an inability to solve the problem”. Marcel Lesieur, 1987.
How can you prevent this turbulence effect? Let’s start with explaining what turbulent flow is.
In general it can be said that there are two types of flows: a laminar flow and a turbulent flow. In picture 1 laminar flow has been visualized by an experiment using ink in a cylindrical tube. The ink has been injected into the middle of a glass tube through which water flows. When the speed of the water is still low, the ink does not appear to mix with water, the stream lines are parallel; this is called laminar flow.
If the speed of the water increases, a sudden change will occur at a certain speed. The flow completely disrupts and the water turns homogeneous through the ink. The stream lines are chaotic, not linear anymore, which is called turbulent flow.
In theory the flow pattern depends on four variables:
Instruments with a bypass sensor work based on a main flow going through a restriction and a small part of the flow going through the actual sensor. The ratio between these two flows is determined by the pressure drop over the sensor and the restriction in laminar flow. The turbulence effect will disturb this ratio. As the instruments with bypass sensor are often used for very precise measurements, the turbulence effect can have a huge effect on the measurement results.
When using thermal mass flow meters with the bypass sensor, it is advised to do the following:
It depends very much on the application what the consequences are of turbulences. As an example in semicon processes, particularly in coating processes such as layer deposition, turbulent flow is out of the question. A stable process is essential here. However, in other coating processes, such as flame spray techniques, the impact of turbulences will be less due the high pressure in the flow.
If you need any assistance for installation of your flow meter, contact our Customer Service Department by submitting the contact form.
For more information about the working principle of the Bronkhorst flow devices, have a look at the various working principles of flow instruments as applied by Bronkhorst.
• Why is the choice of piping important for thermal mass flow meters?
• Why use thermal mass flow meters and mass flow controllers?
• Thermal mass flow sensor: Bypass versus CTA
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