addressing the first problem is an equalizer 50 that is positioned inside of the generally cylindrical distributor pipe 40 preferably the vapor flowing into the distributor pipe 40 would have a consistent velocity as measured transversely across the distributor pipe 40 or at least the velocity would be concentric around the center or axis of the distributor pipe 40 so that as the vapor spreads out across the head space 24 to the peripheral ducts 25 at about the same velocity for each direction for example fig2 shows a flow arrangement that is not desirable where vapor moving along the directions indicated by arrow 16 a is moving much faster than the vapor flow indicated by smaller arrow 16 b what would be desired is that flow in all directions across the head space 24 would be close to the same such as shown by intermediate arrow length 16 c thus vapor flow in direction 16 a would be moderated or tempered down causing flow to increase in direction 16 b such that both are about the same velocity as in direction 16 c if these flows are not balanced the catalyst in the high velocity areas are inclined to be used up before the catalyst at the low velocity areas are used at all in some reactors low velocity causes.