Measuring laminar flow - Höntzsch Messgeräte

Laminar flow in paint booths, clean rooms, semiconductor production or filling processes



Process data

Measuring task:
Flow velocity for process regulation

Measuring point:
Where laminar flow exits, below the filter

Measuring range:
Up to 1 m/s

Process pressure:

Process environment
Typically: +10 .. +30 °C

Your advantage

The process is regulated and secured by measuring the laminar flow – around the clock!

Laminar flow sensors with an integrated transducer and mounting components

With hydrogen peroxide, formaldehyde or alcohols


In laminar flow, air is directed from top to bottom through targeted ventilation. Due to the low flow velocity there’s no cross flow meaning that the laminar flow’s single flow streams stay separated from each other. These low in turbulence laminar flows are necessary to ensure the required air exchange in clean rooms or glove boxes. It’s important that the laminar flow doesn’t cause a stir of small dust particles. Therefore flow velocity in process integrated air conditioners has to be quite low. Laminar flow is also required in other applications such as paint booths or ventilation in buildings. It has been relevant in the area of workplace ventilation and safety long before Corona. Clean rooms are important in medical-pharmaceutical and biotechnological fields to create controllable and therefore replicable environmental conditions. Optimally regulated air conditioners play a significant role in surgery rooms. Other areas that require replicable clean room conditions are electronics and wafer productions as well as many laboratories in basic research and material research. Special applications in the packaging industry also require clean room conditions that are unimaginable without the right sensor technology to monitor and regulate the installed air conditioners. 

Recommended products

Thermal Probe TA10C

ProductProduct data sheet

Vane wheel ZS30

Product Product data sheet

Laminar flow – necessary for a number of demanding processes

Laminar flows in different applications ensure the desired environmental parameters for each process. Compliance and monitoring flow velocity is inevitable to achieve the required results. In clean rooms where laminar flow enters, our vane wheel sensors come to use to monitor direction of flow. All typical applications for laminar flow measurement require highest reliability and accuracy.

Laminar flow in paint booths

When spray painting, flowing coating particles pass the product. To keep the paint booth as clean as an actual clean room the overspray is transported through a focused laminar air flow to the bottom, and there collected and disposed of. The sedimentation rate has to be within a defined range. Flow too low leads to unsufficient removal of the overspray. Flow too high causes poor paint results partly caused by possibly stirred up dust.


Laminar flow in the semiconductor industry

In semiconductor production an ultrapure environment is the foundation for  manufacturing top-quality wafers and circuit boards. Continuous air exchange ensures clean room conditions. Fans blow air through special HEPA filters into the production area. Flow velocity is measured directly below those fan filter units. Laminar flow velocity is only allowed to fluctuate within a very small range.

Laminar flow in gloveboxes

Gloveboxes are containers that are hermetically closed off from their environment. Through integrated gloves in such containers the user can perform work within the container. A laminar flow within the container prevents floats from entering and at the same time removes occuring particles.  


Highest quality and safety

Höntzsch thermal flow sensors TA10C are GMP (good manufacturing pratice) compliant and sterilisable with hydrogen peroxide, formaldehyde and alcohols. They are explosion-proof for the use in category 3G + 3D. These laminar flow sensors are perfectly suited for applications in the industrial, medical-pharmaceutical or biotechnological area whether in a clean room or glovebox.


Annex 1 to the EU GMP guidelines

The minimum requirements for the qualification of cleanrooms are documented in Annex 1 to the EU GMP guidelines, which came into force on 25 August 2023. The main part of the qualification process is the classification according to EN ISO 14644 (series of standards for cleanrooms).

The guideline value for low-turbulence, i.e. laminar displacement flow, is still 0.36 - 0.54 m/s for a homogeneous air velocity at working height. However, unlike in the past, the flow velocity outside this range can now be adjusted in consideration of contamination protection. This must then be justified accordingly. The air flow within the cleanliness zones must be visualised to verify the protective effect in the working area.