In this installment of Ask The Experts, noted process control authority and CONTROL Columnist Béla Lipták and his cadre of automation experts answer a readers question regarding control valves for slurry services.
There are two main drivers for partial stroking of valves in safety systems: the desire to extend manual test intervals to as long as possible; and to reduce the amount of redundant hardware required for higher safety integrity levels. Like most things in life, it all boils down to one thing: trying to save money.
To make the most of diagnostic equipment used in chemical processing, technicians must stretch their knowledge of control valves and related diagnostic equipment that keeps tabs on valve health and safety.
Consider a variety of factors to select a unit that comes the closest. What steam traps lack in size, they make up for in numbers. In a typical steam plant, their numbers range from several hundred in a large steam plant to more than 20,000 in refinery or chemical complexes.
Valves and actuators designed for handling radioactive waste must meet strict government requirements. This sometimes requires unconventional solutions. Such was the case at the Hanford Waste Treatment Project (WTP), Hanford, Wash.
ControlGlobal.com contributor David W. Spitzer provides a look from a process automation perspective at how magmeters and Venturi meters are vying with ultrasonics for clean and dirty water applications.
Handling slurries (a mix of solids and liquids), should be based on experience and experiments, not theory. Much of the knowledge obtained from pneumatic conveyors and fluidization systems can be used in understanding slurries.
When it comes to selecting and sizing control valves and positioners, this article not only helps you pick the right one for the right job, but also includes a valuable valve selection chart you can download!