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Diaphragm Selection – Tips From Our Customers

Here’s how some of our experienced customers go about selecting a diaphragm material for processes. Their methods have been proven over time, which is what makes them valuable.

Most processes in which ASEPCO valves are used are for pharmaceutical or bio-pharmaceutical manufacturing. These are typically CIP/SIP applications, the majority of which can be described as aqueous salt and protein solutions.

Silicone, EPDM, and Viton – which should you choose?

It is not uncommon, however, to see ASEPCO valves used in more aggressive chemical environments. This is no doubt due to the fact that we also offer a variety of other diaphragm materials from EPDM to Viton GF.

So, just how do you go about selecting a diaphragm for a new process? Here are the tips from our users:

  1. Gather Data. Find out what is already known about how certain elastomers perform in your process. Become familiar with how well they perform in which locations and cycles. The gasket material currently used can give you a good clue to approximately what works.
  2. Check the generic chemical compatibility tables produced by elastomer makers. (For example, www.coleparmer.com/Chemical-Resistance.) This data mostly tells you what not to select as a diaphragm, which can be very useful.
  3. Make your best judgment in diaphragm selection based on actual experience at your facility combined with the compatibility tables. Nothing we can suggest will match the value of your experience. Trust what you learn from your production and maintenance people and use their experience as guidance.

Silicone Diaphragms – the most common choice

Now, when you have ASEPCO valves in operation, the big question becomes, “How often should we change out the diaphragms??”

Like the diaphragm selection procedure, this varies from process to process, but here is another set of hints from our users:

  1. Observe the diaphragm as it goes into your process and starts to develop a “life.” When you are installing a diaphragm in a new process, we suggest you look at it at least once a month at a minimum. Open up the valve, look at the diaphragm. No big deal, it takes less than a couple minutes to do this!
  2. Keep your staff on the lookout for any signs of increasing overall diaphragm stiffness and any incipient cracks/tears. In short, learn what the diaphragm looks and feels like as it ages.
  3. Our most finicky clients (parenterals makers) tell us that they like to start with the following generic rules (when using a silicone diaphragm) to ensure changing the diaphragm long before it’s needed:

    a. For FEWER THAN 5 SIP cycles/week (less than 2 hours each at temperatures under 135°C), consider annual diaphragm changeout.

    b. For 5 OR MORE SIP cycles/week (less than 2 hours each at temperatures under 135°C), consider changing out the diaphragms every six months.

Now let us tell you that these pickiest of clients have never met an aging ASEPCO diaphragm. And they don’t intend to. They prefer to switch out the diaphragm while it has a huge percentage of its life yet to live. Yup, they just toss it while it’s still fresh. But, we understand.

On the other hand, a veterinary and a generics client both have reported diaphragm lives that are nothing short of miraculous. For example, the all-time record for an ASEPCO silicone diaphragm was 2.5 years while being steamed up to 6 times a day! Wow, were we impressed.

EPDM– an industry standard

Then we got a call recently and were told that an ASEPCO silicone diaphragm had lasted 4 YEARS while being steamed a few times a week.

In both of these cases, we noted with great interest that the valves were cleaned by hand. Perhaps the more aggressive acids and bases in CIP solutions age diaphragms faster.

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