From time to time I get the opportunity to sit in on product trainings offered here at Crane Engineering. A couple weeks ago, I attended a session on sanitary valves, presented by Chris Johnson, one of our account managers. He demonstrated the function and features of each sanitary valve and discussed which were hygienic and which were aseptic. After the presentation, I asked Chris to help me understand what the difference is. Turns out, I wasn’t the first to ask.
The term aseptic means to be free from contamination caused by harmful bacteria, microorganisms, or viruses. When applied to valves, it means the materials and surface finish of the valve are optimized for exceptional cleanability. It also means each component of the valve that comes in contact with the process is hermetically sealed from the environment and atmosphere that surrounds the process. This is acheived by using a bellows on the valve stem to prevent harmful bacteria, et al, from getting into the process.
How hygienic and aseptic valves are similar
Hygienic and aseptic valves have a lot in common. They share similar materials of construction, and smooth surface finishes. Their design also requires there is no place for bacteria to hide within the valve. Despite their similarities, there are distinct differences between the two.
How’s hygienic different from aseptic?
While aseptic valves aim to prevent contamination from the environment, the focus of hygienic valve design is easy cleanability.
Parts of a hygienic valve will move in and out of the process, becoming exposed to the surrounding environment. For instance, a rising stem on a valve will come in contact with the process, and may also come in contact with the environment outside the process.
Take a look at this video of a hygienic mixproof valve from Rieger Valves. Here you can see as the valve opens and closes, the stem exits the body, and returns to the body.
Compare with this aseptic mixproof valve. Note how the bellows come into play.
When do I use aseptic or hygienic valves?
Aseptic valves, are most often found in industries that require high levels of purity. These include manufacturers of injection drugs, cosmetics, microelectronics, and the like. Aseptic valves are used here to control processes and minimize contamination from environmental sources.
In sanitary applications, valve design matters! If you're unsure which valve is best for your process, talk to an engineer. They can help determine which valve will achieve your objectives for production and cleanliness.
Not sure which valve is right for your process? Ask us about it! We gladly provide technical assistance to businesses and municipalities in Wisconsin and upper Michigan.