Flow rate is a straightforward sounding parameter on the face of it: the volume of a fluid passing through a cross-sectional area per unit of time. So far, so simple. However, where matters become slightly more convoluted is in the science of flow rate measurement. With the right tools and knowledge this needn’t be a chore, as fluid control expert Bürkert UK explains. Read on to find out the advantages of accurate flow rate measurements.

What is flow rate and why do we need to measure it?

Flow rate is the volume of fluid that passes through a given cross-sectional area per unit time. Accurate flow rate measurement using an appropriate flowmeter is paramount to ensuring fluid control processes run smoothly, safely and cost-effectively. Despite its undeniable importance, flow measurement is sometimes a poorly understood area and subsequently not given enough consideration or investment.

The measurement of flow in liquids and gases is a vital parameter in many applications. The quality of some products can even hinge on the accuracy of flow measurements. As well as maintaining the welfare of consumers, precise flow measurements also play an important role in maintaining an appropriate level of health and safety for personnel, processes and mission-critical equipment.

A raft of general and application-specific factors can adversely impact the accuracy of a flow measurement system. These range from the glaringly obvious, like ensuring a flowmeter is correctly installed and accurately calibrated, through to rather more complex and time-consuming issues to resolve, such as contaminants, corrosion and deposition found within the flow path.

How to calculate flow rate

The majority of flow rate measurement devices provide an inferential flow rate calculation based on the fluid’s velocity. Velocity is determined by the pressure differential that forces the fluid through the pipe. The pipe’s cross-sectional area is constant and this is what makes average velocity a reliable indicator of the flow rate. Flowmeters are the foremost flow measurement and control devices for these types of applications.

Burkert can make your life that little bit simpler with the Bürkert Fluidic Calculator. This free resource allows you to calculate a valve’s flow rate, Kv factor (the achievable flow rate of a fluid through a valve) and pressure drop (the difference between the input pressure of the medium upstream of the valve and the back pressure downstream of the valve). You can choose from a variety of media or even create your own.

The advantages of accurate flow rate measurement

Three of the main advantages of accurate flow rate measurement are as follows:

Quality control

Flow rate measurement is an essential parameter in many applications. Whether you are measuring gas or liquid, it is vitally important to ascertain that the right fluid is going to the right place at the right time. Flow rate measurement is especially important in applications requiring stringent quality control, such as batch control or time-pressure dosing processes in the pharmaceutical industry.

Health and safety

The health and safety of personnel is at the forefront of all industrial processes and none more so than those involving liquids and gases. Taking regular, reliable and accurate flow rate measurements is one of the best ways to protect the safety of personnel. A safer working environment is likely to be a more productive environment, with machinery operating efficiently and downtime kept to a minimum.


There are inherent cost-efficiencies that arise as a direct consequence of adhering to high standards of quality control and plant safety. In pharmaceutical and F&B applications, there is an obvious cost benefit of using flowmeters to detect dead legs and minimise wastage of expensive media. Furthermore, if pipelines and machinery are kept operating optimally, the subsequent reduction in maintenance delivers tangible savings.

Flowmeters and mass flow controllers

Flowmeters measure the linear, nonlinear, volumetric or mass flow rate of a liquid or a gas. Bürkert manufactures and supplies a wide range of flowmeters and mass flow controllers to suit a wide range of fluid control applications.

Type 8035 Inline flowmeter or batch controller

The Type 8035 flowmeter or batch controller is specially designed for use in neutral, slightly aggressive, solid free liquids. This device is made up of a compact sensor-fitting with paddle wheel and a transmitter, which are quickly and easily connected using a bayonet fitting. The Bürkert designed sensor-fitting system ensures simple installation into all pipelines from DN06…DN65.

Type 8098 FLOWave SAW flowmeter

The Type 8098 FLOWave SAW flowmeter is based on Surface Acoustic Wave (SAW) technology and is designed for applications requiring the highest levels of hygiene. Stainless steel materials and a measuring tube free of wetted parts provide the ideal sanitary design. This also makes for a flowmeter device that is easy to clean, compact, lightweight and simple to install.

Type 8750 Flow Rate Controller

The Type 8750 flow rate controller represents a closed flow control loop to measure and control gases using the differential pressure principle. This reliable and robust system consists of a control valve, compact process controller on top of the valve and two pressure transmitters. It does not need a separate flow meter and the valve seat serves as variable orifice, which significantly increases the measurement range.

For more information, please visit Bürkert.

Bürkert is a world-leading manufacturer of control and measuring systems for fluids and gases. With a wide range of solenoid valves and other control instrumentation, they have the facility to adapt and develop existing technology to suit customer needs. Their products are suitable for a wide range of applications, including renewables, food and beverage, pharmaceuticals, water treatment, gas handling and microfluidics. For more information, contact the Bürkert sales team on +44 (0)1285 648 720 or email [email protected].