Often there are references to valve-caused problems or difficulties. The list of problems include valve erosion from process media,stickiness caused by excessive friction (stiction),excessive play in valve to actuator linkages (typically found in rotary valves) that causes deadband, excessive valve stem packing leakage, and valve materials that are incompatible with the flowing medium. Any one,or a combination of these difficulties, may affect process quality and throughput with a resulting negative impact on mill profitability.
Many of these problems can be avoided or minimized through proper valve selection. Consideration should be given to valve style and size, actuator capabilities, analog versus digital instrumentation, materials of construction, etc. Although not being all-inclusive, the information found in this sourcebook should facilitate the valve selection process.