The volume flow is an important variable in many industries - whether in air conditioning technology, mechanical engineering or environmental technology. But what exactly is volume flow and how can it be determined? In this article, we explain the basics of volume flow, how it is calculated and how it relates to cross-sectional area and flow velocity. We will also introduce you to our new volume flow calculator, which makes the calculation even easier.
What is volume flow?
The volume flow is the volume of a liquid or gas that flows through a cross-section within a certain time. It is measured in cubic meters per second (m³/s), liters per minute (l/min) or other similar units. This quantity is crucial for understanding how fluids - i.e. gases or liquids - are moved in systems and how machines or systems must be designed to transport a certain amount of fluid.
To simplify matters, we assume idealized, i.e. incompressible, fluids such as water.
The volume flow formula
The most common formula for calculating the volume flow is as follows:
Q = A x v
Here, Q stands for the volume flow, A for the cross-sectional area of the pipe or duct and v for the average flow velocity of the fluid. This formula shows the direct relationship between the cross-sectional area through which the fluid flows, the velocity of the fluid and the resulting volume flow. The volume flow is directly proportional to the cross-sectional area and the flow velocity: if the area is larger or the velocity is higher, the volume flow also increases.
However, an increase in flow velocity can also lead to increased friction losses and therefore require more powerful pump or drive technology. The aim here is to find an ideal middle ground in order to optimize energy efficiency and material stress.
It is important to note that the volume flow formula is based on the assumption of the average flow velocity. This is because the flow velocity within a pipe or duct is not constant everywhere. Closer to the edge, where the fluid is in contact with the wall, the velocity is lower than in the middle due to friction. This variation in velocity across the cross-section is even more pronounced in turbulent or non-laminar flows.
Laminar flows, where the fluid moves in parallel layers without mixing, typically only occur at low velocities and in small pipes or with very viscous fluids. However, in most real applications, especially at higher velocities or in larger pipes, the flow will be predominantly turbulent. In a turbulent flow, the different fluid layers mix, resulting in a more uniform velocity distribution in the cross-section.
When it comes to calculating the volume flow, the average flow velocity is used, which indicates the average velocity of the fluid over the entire cross-section.
Units of the volume flow
The volumetric flow rate, which indicates how much volume of a fluid flows through a certain cross-section per unit of time, is expressed internationally in a variety of units. The standard SI unit of volume flow is cubic meters per second (m³/s), a unit of measurement commonly used for large industrial applications. In technical applications and in everyday use, it is also often expressed in liters per minute (l/min) or cubic meters per hour (m³/h). These are particularly relevant in heating, ventilation and air conditioning technology as well as in hydraulics, as they correspond better to the application context and are easier to handle.
Use our volume flow calculator
With our new volume flow calculator you can calculate volume flow, flow velocity or pipe inside diameter quickly and easily. Simply enter the known variables and our calculator will provide you with the volume flow in the desired unit. This tool saves you time and reduces the error rate when calculating manually.
Whether you work in heating and ventilation technology, water treatment or have to deal with fluid flows in other industrial applications - our volume flow calculator is a simple tool for your everyday work.
Measuring the volume flow with the volume flow meters from SEIKOM Electronic
For precise determination of the volume flow or flow velocity in piping systems, the volume flow meters RLSW®8 and the soon-to-be-released RLSW®9 model from SEIKOM Electronic offer reliable solutions, optionally even for volume flow measurement in environments up to 350°C. These precise instruments have been specially developed to provide users in industry and technology with reliable and user-friendly measurement.
The measuring principle of the RLSW®8 volumetric flow meter is based on flow measurement using hot-wire anemometry or the calorimetric measuring method which can measure even the lowest velocities and volume flows. Users can simply insert the device into the piping system and measure the flow velocity directly and easily. The device automatically converts this measurement data into the volume flow and shows it on a clear display and provides a linear analog signal for further processing in the PLC.
Whether for maintenance work or for checking heating, air conditioning and ventilation systems - the RLSW®8 and RLSW®9 flow meters provide professionals with precise tools to optimally monitor and regulate the performance parameters of their systems. The measuring devices are designed to be easy to use and robust enough for daily use. The digital display allows users to read measured values precisely and use them to monitor and optimize their processes. This is particularly important when implementing measures to increase efficiency or for error analysis.
Our team will be happy to help you select the right measuring device for your application. You are welcome to take a look at our various solutions in the field of flow monitoring and measurement to find out more about our devices for measuring and controlling fluid flows in your applications.
