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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Learn more about how Coriolis-based flow meters can be used as microfluidic flow meter instead of thermal flow meters. Read the customer story of a microfluidics system builder who used Bronkhorst products.
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 mass flow instruments that use a bypass are what most people have in mind when they think of thermal mass flow instruments. The principle is shown in Figure 1.
In this configuration, the mass flow is measured in the bypass (or sensor channel) instead of the main flow channel itself. This sensor is operated in the laminar flow regime.
The bypass is a capillary tube with thin metal walls, in two locations surrounded with metal wires that can heat the tube and measure (‘sense’) the temperature as well. The small diameter of the capillary tube allows for fast response times and low energy requirements, because only a small tube volume needs to be heated. However, a filter is required prior to the mass flow meter to prevent plugging of the capillary tube.
A laminar flow element – which is a flow obstruction in the main channel of the device – allows a proportional part of the fluid to flow through the bypass (or sensor channel), in parallel to the main flow channel.
The laminar flow element (or flow splitter) consists of a stack of stainless-steel discs with high-precision etched flow channels, having similar characteristics as the flow sensor. For higher flow rates, the discs are equipped with an additional section to filter out turbulence effects. Using this element ensures stable and reliable flow proportioning, even under varying process conditions.
Do you want to learn more laminar flow elements? Read our blog about this critical element for flow meters which use the bypass principle.
The gas flowing through the sensor is warmed by two heaters (RHT1 and RHT2 in Figure 1). The temperature of the tube is measured at the same two points, so these heaters are sensors as well. With no flow present, the temperature difference between the two points in the bypass will be zero. When the flow increases, the temperature at the first measuring point (RHT1) falls as fluid carries away the heat. At the same time, the temperature at the second measuring point (RHT2) becomes higher because the fluid carries heat to it. A higher flow will result in a larger temperature difference, which is directly proportional to the mass flow.
A clean, dry gas application where higher accuracy as well as repeatability are important is a good application for a bypass device where a proportional part of the flow is passed through a flow restriction, such as in the EL-FLOW Select, EL-FLOW Prestige, IN-FLOW and EX-FLOW devices. EX-FLOW devices are suitable for gas flow applications in hazardous (ATEX) areas.
As a variant of the bypass principle described above, Bronkhorst designed a special configuration for low pressure-drop applications - the LOW-dP-FLOW series. The sensor only requires approx. 0.25 to 2.5 mbars. Furthermore, the larger flow channels minimise the risks of clogging and facilitate cleaning and purging. Therefore, this configuration is preferred for corrosive gas applications.
Thermal mass flow meters are used to measure mass flow of low gas flow. A mass flow controller is a flow meter combined with a control valve.
A new era of Mass Flow Control; FLEXI-FLOW Mass Flow Controllers. To measure & control gas flow, temperature and up/downstream pressures.
Bronkhorst High-Tech designs and manufactures innovative instruments and subsystems for low-flow measurement and control for use in laboratories, machinery and industry. Driven by a strong sense of sustainability and with many years of experience, we offer an extensive range of (mass) flow meters and controllers for gases and liquids, based on thermal, Coriolis and ultrasonic measuring principles. Our global sales and service network provides local support in more than 40 countries. Discover Bronkhorst®!