In the second and final part of our series on crime and abuse, you are going to find out ways that you can help stop abuse before it happens. If you recall, in the first part of the series we showed you common ways diaphragms were abused (if you didn’t see it, you can go here to read the article: http://asepco.com/2012/01/diaphragm-abuse/) So, how do you avoid these problems?
It is relatively easy to avoid most of these abuse problems.
- Problem #1: You change out your diaphragm less than once a year.
There is always variability in how long a diaphragm can be used in a process before being replaced. Depending on how your system is operated, how often the diaphragm is exposed to chemicals and elevated temperatures and the diaphragm material you choose, the life of your diaphragm can be as short as a single run or as long as a year (in some cases longer). Of the different ways diaphragms can be abused this is the one that initially takes the most diligence and should be periodically reviewed to take into account any potential process changes.
When you first install a diaphragm into a system, you need to be aware of how it may react with your process and you need to periodically inspect the diaphragm to ensure it is still in working condition. CIP/SIP exposure can have a significant impact on diaphragm life. For example, depending on duration of exposure and frequency of exposure, you may need to replace a silicone diaphragm as frequently as every three months. However, under the same conditions you may be able to use an EPDM diaphragm and extend your replacement frequency to every 12 months.
- Problem #2: When installing the diaphragm on an actuator, you don’t put it all the way on.
Diaphragm threaded on partially
Diaphragm threaded on correctly and completely
This is probably the simplest problem to overcome. Every diaphragm is shipped with instructions showing you how to properly install the diaphragm. As long as these instructions are followed, you can avoid this problem.
- Problem #3: You use the diaphragm at a higher temperature then it is rated for, say using a silicone diaphragm at over 135°C.
OK, we know you aren’t gonna take a blowtorch to a diaphragm, but you should always consider what temperature your diaphragm is rated for.
This is another simple problem to prevent. The temperature ranges of our materials are available here: http://support.asepco.com/activekb/questions/148/What+is+the+temperature+range+for+an+Asepco+diaphragm%3F
By using a material that meets or exceeds your temperature requirements, you can avoid a premature failure caused by overheating your diaphragm.
- Problem #4: You don’t ever service your pneumatic actuator.
Look, Ma! No hands!! Seriously, if you can float a ping pong ball, it’s time to replace the seals.
This is one of those things that is often overlooked. Because actuators are nonproduct contact components and they typically last for very long periods of time, they may not be getting serviced at appropriate intervals. While an actuator can perform for years and years without any problems, we recommend performing preventative maintenance at least every two years with heavy use and every three years with light use. This prevents introducing air behind the diaphragm and potentially rupturing the diaphragm.
- Finally, Problem #5: You’re using your diaphragm with process fluids it can’t handle.
This can be a tricky problem to prevent. Because every process is different, your needs may vary greatly. There are many chemical resistance/chemical compatibility charts that can be found on the Internet and while they provide some guidance, they should be taken with a grain of salt. Most of these charts have been created using a piece of elastomer in a static state. This gives you good general compatibility information, but your results vary depending on how often you use the diaphragm and what stresses it sees when it is exposed to the fluids you use in your system.
As you can see, preventing diaphragm abuse is relatively easy. If you are interested in seeing the results of the most common diaphragm abuses, then go to http://asepco.com/asepco-products/diaphragms/ and check out our Free Report on diaphragms.