In any type of system where high purity levels are required, ensuring that every component in the system meets at least minimum standards will be a critical factor. This includes the major system components such as pumps as well as the smaller parts including high purity valves.
Often, the amount of attention and research that goes into choosing those big components is significantly more than when choosing valves, fittings, and connectors as well as other flow devices. Unfortunately, not paying attention to the quality, durability and the reputation of the manufacturer of the high purity valves that are selected can result in costly problems.
The Correct Design and Materials
While all ball, diaphragm, check, metering, solenoid and pneumatic valves have a similar design and function; the top manufacturers build in additional features that are critical to the prevention of the buildup of material in the valve. These areas that can include what are known as “dead cavities” as well as poor surface finishes pose a very real risk of the build-up of biofilm and other types of contaminants in the system. Typically, wetted surfaces will utilize PTFE to prevent corrosion as well as facilitate the flow of media through the valve.
In addition, when the high purity valves are not manufactured in cleanrooms and under precise quality control protocols, it is very likely that contamination from airborne particles, residues, and areas where the wetted surface is not uniformly treated will result in serious problems as the system operates.
Other Factors Of Note
While the type of interior wetted surface is always a central consideration, the material that forms the exterior of the valve also has to be selected for the specific application. In most cases, natural PVDF and polypropylene are highly durable, long life cycle options that can stand up to demanding environments and also help to reduce the cost per unit of valves throughout the system.