Type AN follows DIN 24960 to fit into existing stuffing box spaces. The seal is very compact and is completely enclosed, preventing particles from damaging or blocking its motion. The seal is of sanitary design, without gaps for the product to get stuck in.
Type AO is designed for assemblage at the atmosphere side of the seal cover. Thus it will work as single pump seal for the media as well as secondary seal for the flush media through the seal cover.