Measuring airflow in sterilising tunnels in the pharma industry

Measuring airflow in pharmaceutical filling lines and sterilising tunnels

Process data

Measuring task:
Flow velocity for process regulation

Measuring point:
At different points of the sterilising tunnel, also in the heating zone

Measuring range:
Up to 1 m/s

Process pressure:

Process environment:
Up to 300 °C


Pharmaceutical products are sterilely filled in special machines and plants. The hereby used containers (usually glas containers – vials), have to be cleaned and sterilised.

After washing, the vials are led to a sterilising tunnel for sterilisation. They are transported with a special conveyance through a preheating zone to the heating zone of the hot air steriliser. Hot air is blown onto the vials to sterilise and depyrogenate them.

In sterilising tunnels hot air flows through the so called HEPA-filter down into the heating zone. There, sterilising hot air with a very low flow velocity is blown down to the glas containers.

Since it determines the process, flow velocity needs to be measured and monitored closely.

Your advantage

The process is continuously regulated and ensured by flow velocity measurement

Our sensors are perfectly suited for use in the heating zone in temperatures higher than 300 °C

Tried and tested
Well-known plant manufacturers have been valuing our sensors for decades.

Recommended products

Vane wheel ZS30

Product Product data sheet


The pharmaceutical industry has highest standards for their sterilising processes

Highest quality and cleanliness of pharmaceutical products is a result of excellent plant engineering. Leading plant manufactures have been putting their trust in Höntzsch measuring technology for decades.

Filling sensitive pharmaceutical products is a highly complex process. It has been continuously improved in the past years. Leading manufacturers of sterilising tunnels offer, depending on the plant’s capacity and final product a variety of suitable plants.                      

Sterilisation of the glas containers is an inevitable necessity in the pharmaceutical industry. They have to be washed in a washer system before hot air sterilisation can begin.    

Where to measure in the sterilisation process?

Next step: the containers go through the sterilising tunnel in the following steps:

1. Drying (preheating)
2. Sterilisation and depyrogenation (heating zone)
3. Cooling

Höntzsch sensors are at work directly inside the sterilising tunnel. They monitor laminar air flow that’s necessary for the hot air sterilisation.


How does hot air sterilisation work?

In all three steps of the process each air flow is monitored with vane wheel sensors. The heating zone has the highest demands for measuring technology with temperatures over 300 °C. This is necessary to achieve the required reduction of microorganisms. The high temperatures lead to a decrease in atmospheric density. At the same time flow velocity is within the low range of only 1 m/s.

The sensor has to reliably measure flow to ensure the success of the hot air sterilisation and therefore the safety of the pharmaceutical product.   
This makes requirements in the pharmaceutical industry quite high.


Why are these sensors basic equipment for the pharmaceutical industry?

Höntzsch developed the perfect solution for these very special pharmaceutical applications and has been improving it over the years in close cooperation with the plant manufacturers. The result is our vane wheel sensor ZS30, which is worldwide known in the industry of measuring technology as „state of the art“.

This solution is well established among leading pharmaceutical companies!!

Following the sterilising process is filling the vials with the actual product. Based on these experiences we’re able to offer many similar solutions for the chemical and pharmaceutical industry.

An example is the monitoring of drying plants and ovens. Low flow velocities in combination with high temperatures have to be measured reliably.