There are a variety of plastic knobs that are particularly suited for manual valve controls.  Bart/T knobs are the most popular plastic knobs used for manual valve control applications. Here are examples of different shapes of bar knobs available.  

We have a long history of manufacturing plastic knobs, especially phenolic plastic knobs.  But we also mold phenolic custom plastic parts, such as the plastic butterfly valve for the oil & gas industry. We started manufacturing butterfly valves a few years ago because the company that needed them got fed up with their overseas vendor. 

Are your metal parts rusting or denting?  Do you need multiple operations such as welding and bending to machine your metal part?  If you answered yes to either of those questions, you should consider switching to a plastic part.  Plastic parts resist rust and denting, can be custom colored, and have high impact strength - not to mention are cheaper to produce.  Want to learn more?  We've put together a 24-page ebook to help you learn more converting metal to plastic parts and about the molding process-click here to view our optimized process, or call to schedule a design consultation today.  Visit our product portfolio to learn more about metal to plastic conversion parts for the Automotive, HVAC, and food Service Industries.