Measuring Pressure in Steam Sterilizers

Whether it’s a pressure cooker in the family kitchen or a big industrial autoclave, airtight pressure tanks have to be monitored very closely. As a manufacturer of large steam sterilizers, Belimed Sauter AG relies on pressure transmitters to ensure performance and safety through constantly changing temperature conditions.
By Andrew Sim, Baumer, U.K. March 1, 2009

Whether it’s a pressure cooker in the family kitchen or a big industrial autoclave, airtight pressure tanks have to be monitored very closely. As a manufacturer of large steam sterilizers, Belimed Sauter AG relies on pressure transmitters to ensure performance and safety through constantly changing temperature conditions.

The special transmitters with the Neumo BioConnect flanges are in a vertical line along the right edge. Source: Baumer
The special transmitters with the Neumo BioConnect flanges are in a vertical line along the right edge. Source: Baumer

The Swiss-based company was founded as a blacksmith’s shop in 1923 by Josef Sauter. In 1976, the company started producing sterilizers, decontamination, and disinfection systems. Today the company has more than 200 employees and builds sterilizers for pharmaceutical and biotech manufacturers, along with hospitals, laboratories, and research institutes. Since 1999, the company has been part of the Belimed Group that offers instruments and services for the worldwide infection control market.

Baumer Bourdon-Haenni AG has been a regular supplier of pressure monitoring devices for Belimed Sauter’s production of autoclaves, particularly the ED 701 sensor equipped with a clamp-on process connection. The ED 701 is a piezo-resistive pressure transmitter with a stainless steel diaphragm for industrial and hygienic applications. This model was used in a special group of autoclaves Belimed Sauter built for Sanofi Aventis using the Neumo BioConnect aseptic connection. This mounting system uses a V-shaped flange with a nominal diameter of 48.3 mm and an external diameter of 100 mm. Since there are no relevant hygienic standards for this proprietary product, Baumer had to construct it to Neumo’s specifications. The connection is sealed with an O-ring protected with a ridge to prevent it from being crushed when the flange is screwed together.

The design of the ED 701 series makes it suitable for applications in the food and beverage processing industry as well as pharmaceutical and biotechnology applications. Any parts with media contact are made of 316L / 1.4435 stainless steel and all materials, including the white oil used as fill liquid, are compliant with U.S. FDA standards.

For more standard pharmaceutical sterilizer applications, each unit uses two pressure transmitters with a range of 0-4 bar (0-60 psi). An additional unit with a pressure range of 0 to 6 bar (0-90 psi) is inserted into the steam supply pipe.

Belimed Sauter has evaluated a variety of pressure sensors, but given this difficult and critical application, the company prefers to use what it knows works. Rolf Germann, head of logistics for the company says, “We decided to use Baumer products because they offer high accuracy and stability even in environments with big temperature variations like our sterilizers.”

Author Information
Andrew Sim is managing director for Baumer, U.K. Reach him at info.uk@baumerprocess.com .