When making a valve selection, here are some important questions to ask:

  • Does the valve meet the specifications required for your process?
  • What type of valve best suits your needs: gate, globe, ball, butterfly, check, pinch, etc?
  • How many worker-hours does the valve take to install?
  • Are your employees skilled enough to install the valve or is outside help required?
  • What will outside help cost?
  • Is there a dealer or distributor near you who you can contact for parts?
  • How long will you have to wait for parts?
  • Can you rely on the distributor for service?
  • If the wait for parts means your process is down, how much will it cost in lost product and time?
Beware of low cost; it may mean cheap construction. Make sure the valve is sturdy and the stem is blowout proof. Will the valve be automated? Do you need a fail-safe capability in case of electrical or system failure?

Progress in design has put a great variety of valve and actuator types, each with some special qualification for service, at the engineer's fingertips. From these the engineer may choose the right automated valve package to provide dependable and economical performance.

Because the valve is in contact with the fluid that is either the final or intermediate product of a process, it is often the most carefully selected element of an automated valve package. But before an actuator selection is made, the valve type, material, etc., must be determined, as this may affect the amount of torque required to automate a valve. Having done this the actuator style (rotary or linear), torque (or thrust), output, and type (manual, electric, pneumatic, hydraulic, etc.) may be addressed.

Certain essential information must be known and analyzed before one can select the best valve for the job. Some important questions to ask are:

  • What is the function of the valve? On-off only? Control? Fail-safe?
  • Frequent or infrequent operation?
  • How will it be operated: manually, pneumatically, or electrically?
  • What is the process medium? Is it corrosive or abrasive? What is its volume and velocity?
  • Is the valve being considered available in all materials?
  • What about pressure and temperature? Depending upon the type of material used for a given media the pressure and temperature rating may be severely limited. A completely metallic valve may be necessary to handle an extreme temperature but may not provide the shutoff required.
  • What is the pipe size? Is the valve being considered available in that diameter?
  • How fast must it operate? An automated ball valve can cycle dozens of times per minute, but a gate valve cannot.
  • Should the valve be able to be maintained in line? Should it be a top-entry or three-piece design?
  • How much should it cost? Some 1-inch (in) valves cost as much as $2000, but depending on the application they may still be considered economically feasible.
  • What about weight? A gate valve can weigh as much as 10 times that of a butterfly valve.
  • How critical is availability? Is the valve you select in stock? Can it be automated? Are repair parts available?

Throughout the soon-to-be-released book Valve and Actuator Technology II by Wayne Ulanski, you will find the answers to these and many other questions. You may even find that there are things to consider that are unique to your needs.