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Vacuum, Pressure, Steam… No Problem!

Posted on November 21, 2007

A harsh environment and a tough packaging challenge in the BioPharma and Food & Beverage industries, pretty much sums up the development task for our newest Autoclave Load Cell product: Burns Model 21090.

 

As you may know, the operating conditions of the autoclave process ranges from vacuum to positive pressure steam at temperatures up to 135C. Individually, these conditions are fairly easy to design around, but the combination presents a few interesting challenges in the RTD world – and sealing the device such that the insulation resistance performance is maintained after multiple cycles is the fun part.

 

Other features we designed into our new autoclave sensor include a .125 diameter stainless steel sharp-tipped sensor sheath to facilitate insertion through the rubber membrane of the load cell, and a dual Pt100 element that can support either a 3- or 4-wire operating connection. The cable features a silicone rubber jacket providing the durability necessary to meet the handling concerns that were shared with us from users of large chamber autoclave systems. We also designed a bulkhead/transition system to assist in providing a sealed penetration through the wall of the autoclave.

 

Now back to the sealing challenge!

 

Inside the transition housing (or handle which is laser marked for easy identification) is an elegant design which protects the 8-wire joints, simply yet effectively seals the sensor and involves very few complex parts. The design insures ease of manufacture and an epoxy fill method that results in an extremely stable final assembly.

 

New Autoclave Sensor

 

We're proud of the creativity of the approach and through our design verification testing, we're confident in the high reliability of the Model 21090 in the harsh environment of the Autoclave processing cycle.

 

Got another challenging application?  Comment on the blog or give us a call.

 

- John Zwak, Sr. Design & Metrology Engineer

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