In the Plug Flow reactor Edit menu, under packings, and sub section empty bed we have a text box to enter the Wall dimension. I have gone through the help file but am not so sure, if the information to be supplied is the wall diameter or the wall thickness? How will wall thickness affect the calculations? Also, the wall diameter will always be equal to the reactor diameter for an empty bed. This information is already supplied in the edit> reactor > Reactor Diameter text box.