How to calculate stoke time of an actuator?

I think it has to be measured. It may also be affected by temperature in various ways.

Jerry

I've not come across a "hand ready way to calculate" this. However, in principle the solution is similar to the sort of examples you get in undergraduate thermodynamics text books: flow of compressible fluid out of a cylinder in response to the movement of a piston. The math involves the solution of differential equations for the mass and energy, and for the flow through the orifice and the forcing function - where there are non-linearities. In practice there may be other, difficult to predict, influences, such as actuator stem-friction, out-of-balance forces on the actuator due to process pressure, the influence of pneumatic piping, etc. In summary: a little dynamic simulation (numerical solution of the non-linear differential equations) is required, using your favourite dynamic simulation software package. A bench test on the completed valve & actuator is probably the most practical approach for real kit. I recall that the Neles-Jamesbury (now Metso Automation see: ) research centre in Finland did a lot of work on actuator dynamic modelling, and had a sophisticated model and simulation software that could be used to predict the behaviour of their valve-actuator combinations.

Kelvin B. Hales Kelvin Hales Associates Limited Consulting Process Control Engineers Web:

You could also look at the Valtek sizing and selection info ... here's a link to the sales literature if that helps