The Model ES-660 is a new generation hatch designed with precision-manufactured internal components, a round base and cover, and is intended for use in applications where ultra-tight sealing is required such as sour crude/gas or where strict environmental emissions standards are enforced. The Model ES-660-L is a new generation hatch designed with precision-manufactured internal components, a long base and cover, and is intended for use in applications where ultra-tight sealing is required such as sour crude/gas or where strict environmental emissions standards are enforced. The long basin serves as a thief shelf. The Model ES-660-L also includes an inclining base to keep the basin level.