Bill.. I googled and found this; it appears that the seal can be placed on either end as long as the flared side the seal faces the raw water
FILMTEC Membranes - Brine Seal Location and Direction
Question On which end of the element should the brine seal be placed before loading?
Answer When shipped from the factory, brine seals
are located on the feed end of the element, with the flared side facing the direction of the incoming feedwater. Brine seals can be placed on either end of the elements as long as they seal in the feed stream direction with the flared side facing the incoming feedwater.
When loading or installing new elements, here are a few tips:
- Load the membranes into the feed end of the vessel.
- The end of the membrane without a brine seal should be placed in the vessel first.