Flow metrology

Large quantities of liquids and gases are produced, transported and distributed across the world every day, and even small measurement errors can have huge consequences. We provide reliable and traceable measurements for flow based on the quantities mass, length, density and time.



Large quantities of liquids and gases such as oil, natural gas, water, hydrogen and emissions are produced, transported and distributed across the world every day. Gas and liquid meters (or flow meters) are needed for billing purposes.

We often measure both quantity and quality (calorific value, or the amount of pollutants). A measurement error of just 0.1% can cost large oil and gas pipelines millions of euros every year. As such, reliable measurements that are traceable to international standards are crucial for owners and operators. Other industries that attach great importance to calibrations of liquid and gas measurements are the process and chemical industries as well as power stations.

VSL and flow

Based on our extensive knowledge and experience, VSL has an excellent international reputation in the oil and gas sectors. We provide various flow and liquid volume measurement services for a wide range of parties around the world, including measurement equipment suppliers, utility companies, oil and gas producers, and gas transport and distribution companies.

At European level, we are working on several research projects, including with regard to Liquefied Natural Gas (LNG). Our experts also participate in international working groups, including the BIPM Working Group on Fluid Flow and EURAMET TC-Flow for harmonisation across Europe countries.

VSL realises the Dutch measurement standards for flow based on the quantities mass, length, density and time. In our liquid and gas laboratory, we regularly compare the standards with those of other national metrology institutes. This ensures international recognition. We determine liquid mass and density for liquid volume measures, which are traceable to national mass and density standards.

Would you like to know more about our services?

Our experts are happy to help.

Jaïr Blom
Sales Engineer


We support and advise manufacturers and end users with regard to questions, enabling them to improve measurement and inspection methods to optimise the quality of their processes and products.


Custom flow metrology

VSL’s expertise is regularly deployed in both national and international projects, ranging from realising traceability to advice on and the design of challenging flow measurement systems.

Our knowledge of measurement and the interpretation of measurement data enables us to provide the following services:

  • Advice on and design of measurement systems. We look at all components of the system that affect the measurement with a view to optimising accuracy and measurement uncertainty.
  • (Periodic) on-site validation and certification of complete gas and liquid measurement systems.
  • Calibration of measuring instruments to make them traceable. At VSL or on site.
  • Independent opinions in claims and disputes. In claims and disputes, an independent and reliable measurement can provide a definite answer.
  • Remote monitoring and telecalibration (gas flow only).
  • Uncertainty analyses and various types of inspections.
  • Implementation of quality systems.

Every situation is unique. Do you need advice or would you like to know what we can do for you? Don’t hesitate to contact us.


Flow calibration services

Accurate, traceable flow measurements are of critical importance for flow transactions because of the financial value they represent. In addition to the measurement itself, calorific value (also called heating value), temperature, viscosity and pressure are also important factors in minimising measurement uncertainty. VSL has extensive facilities to calibrate volume instruments, pipe provers, flow meters, and more. Analysis of a complete measurement system allows us to map out its accuracy and measurement uncertainty. VSL establishes the lowest possible uncertainty in terms of volume, mass and flow.

Calibration of flow meters

We calibrate flow meters, such as turbine, rotor, electromagnetic, Coriolis, vortex, soap membrane and ultrasonic meters, both in the VSL laboratory and on site. We also calibrate anemometers, mass flow controllers, mass flow meters, laminar flow elements, rotameters, drum meters and bellows meters. Our facilities have wide measurement ranges. During a laboratory calibration, we compare a flow meter to a measurement standard and determine the measurement error and uncertainty. In addition to liquid and gas flow meters, we also calibrate air velocity meters.

Calibration of volume instruments and pipe provers

Many companies use volume instruments or pipe provers to calibrate their measuring instruments in the field. VSL calibrates these volume instruments and pipe provers so that the measurements made are directly traceable to international unit systems.

Our areas of expertise