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Diaphragm Reliability

a.k.a. Why doesn’t this diaphragm last as long as it used to? Arrgghhh!

It’s pretty frustrating, and costly, when a diaphragm fails. You’ve done your homework, done your testing, evaluated the options, and chosen the best diaphragm for your process. Everything is working just fine, until one day a few years later when a diaphragm fails before its scheduled preventive maintenance (PM). Let me tell you about an experience I had that illustrates this problem and highlights the challenges we face today when it comes to diaphragms and how they function in a bioprocess.

Some years ago, I had a client who had a problem with a failing diaphragm. They had been using the same diaphragm material for nearly 10 years. When they initially started, they performed monthly checks to determine when they should do their PM. They found that the diaphragm lasted one year and one month before it failed. They set their PM interval at one year. For the next several years, they had no problems. Then failures began to occur before the one year point. We set up a meeting and when I arrived, they dumped a box full of failed diaphragms on the table. Looking at the diaphragms it was clear that there was a chemical incompatibility. The customer’s elastomer expert had come to the same conclusion.

The question was, how did this happen? Were there any changes to the diaphragm material or manufacturing process? No, because so many of our customers require diaphragms to be the same as when the diaphragms were validated in their systems, we don’t make changes to material formulations or fabrication processes unless absolutely necessary. If circumstances change, such as a material supplier no longer supplying a material, then we would inform our customers at least a year in advance about the change. Were there any alterations in the customer’s process? Not from a chemistry or temperature standpoint. However, there was one change: batch frequency. When the customer first started using the diaphragms, they were processing one batch a month. When the failures began, the frequency had changed to one batch every three days. Aha! That’s a 10X increase in exposure to CIP, SIP, and process solutions.

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Of course, what the customer said next, left me at a loss for words. He said, “Can you make these diaphragms last longer without changing the material or the way they are made?” I thought for a minute and said, “That really wouldn’t be possible. There are really only two options that will prevent these failures, either change the diaphragm more frequently or change to a material that will meet your new processing requirements.” You, of course, understand his dilemma. Changing diaphragms frequently is time consuming and costly. Changing materials, in this case, would have been very difficult because they validated the system with the silicone material and changing to another material would have required re-validation.

I think this story illustrates some of the challenges faced by the biopharmaceutical industry, especially our opposing desires. On one hand, when a diaphragm is specified in a process, we don’t want anything to ever change about that diaphragm, from its elastomer formula to its production method. On the other hand, the actual bioprocess is constantly changing and diaphragms need to evolve to meet those changes. In order to find a solution to these opposing needs, to better understand your definition of reliability and provide you with the best diaphragm choices for your processes, we would like you to participate in a poll we will be conducting over the next few months.

This poll won’t take a lot of your time and it comes with an incentive. Everyone who participates in the poll will receive a report of the results. You will also be entered in a drawing, with a grand prize that is your choice of amazing prizes for you plus a 20% discount for your company on your next order. Just click this link: http://asepco.com/poll/.

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