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.
Customer satisfaction, innovation and quality of product and service have been the cornerstones of Bronkhorst's success. Based on our experience, innovation and sense of responsibility, a relationship with Bronkhorst assures Performance for Life.
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.
1. What is mass flow rate?
2. How are mass flow rate and volumetric flow rate related?
3. Why use volumetric units for mass flow rates?
4. How to measure and control mass flow rates and volumetric flow rates?
Suppose you want to add a gaseous or liquid compound to a chemical, pharmaceutical or food process. Would it make a difference whether you add a kilogram (as unit of mass) or a litre (as volumetric unit) of such a fluid?
Let’s have a closer look at this matter.
Many processes in chemical or food industry are mass related. Chemical reactions rely on the masses of reactants or ingredients that need to be added in the right mass ratio. And for custody transfer applications - either inside or outside the gas & oil business - the mass of the exchanged fluid determines its price. While in batch processes the supplied mass is relevant, continuous processes depend on mass flows.
Essentially, mass flow rate is the amount of mass of a gas or liquid that flows in a certain amount of time, for instance expressed in kilograms per hour (kg/h) or grams per second (g/s). In an analogous way, a volumetric flow rate is the volume of a gas or liquid that flows in a certain amount of time, expressed in such units as litres per hour (l/h) or cubic centimetres per second (cm3/s).
There is a difference in behaviour when dealing with masses or volumes of fluids. Volumes are influenced by changes in process conditions such as temperature and pressure, while masses are not affected. The same holds for ‘flowing’ masses and volumes.
The density of a gas or liquid, expressed in kg/dm3, relates the mass flow rate to the volumetric flow rate. This density is temperature and pressure dependent: high temperatures generally result in low densities, and high pressures result in high densities for these fluids - although the effect for gases is greater than for liquids. The volumetric flow rate is obtained by dividing the mass flow rate by the fluid density. A volumetric flow rate varies with temperature and pressure, while a mass flow rate remains constant when temperature or pressure changes.
Following the logic above, a mass flow rate should be expressed in units of mass such as g/h, mg/s, etc. Most users, however, think and work in units of volume. That’s fine, and to use density in converting mass flow to volume flow, we must pick a set of specific pressure and temperature conditions at which we use the density value for the gas. Worldwide, there are quite a lot of these standard reference conditions for conversion.
The following reference conditions are used by Bronkhorst:
Keep in mind:
Note which reference temperature and pressure you use in your specific case for conversion between mass flow and volume flow. Please be aware of these differences, because mixing up these reference conditions for gas flows (especially the temperature difference between 0 and 20°C) may lead to an error of 7 %!
We have several mass flow and volume flow instruments available for measurement and control of gas and liquid flows. Instruments that operate according to the thermal or the Coriolis principle are directly related to fluid mass flow, respectively through thermal conductivity and mass inertia.
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.
Do you know how to select the right flow meter? Selecting the right flow meter is the key to success. Check out our beginners' guide.
When you install a flow meter you want the best performance right away. Check out our top 10 tips for installing your flow meter.
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®!