Search the Library catalog and you can find many books on valves which may be relevant. Valves have applications in many fields, such as civil engineering and mechanical engineering. If you find a book that is useful click on the subject headings within the book's full record to find other books like it.
If you need valves within a more specific application, such as artificial heart valves, you may need to think about adding search terms and discarding others. For instance, "artificial hearts" or "biomedical engineering" might be better terms to search for this type of valve.