Regarding your comment: 1) following your advice we will mount the seal vessels between 650 and 1000 mm. above the seals of the horizontal unit This means they cannot be positioned above the vertical unit as originally planned. Please note that while cleaning the complete unit (ATFD - H and ATFD - V) will be filled up with water. 2) According your revised drawing the seal vessels will be atmospheric. 

Please confirm this is ok