Dribble flow valve

Drill pipe inside blowout preventer

Drop check valve

Dual acting check valve dampener

Dual ball valve air vent valve

Dual check valve

Dual check valve structure

Dual component flap

Dual disc low pressure back-check valve

Dual outlet air valve

Dual plate check valve

Dual plate check valve

Dual radius valve stop

Dual speed flow control valve

Dual spring exhaust valve linkage assembly

Duckbill conservation vent valve

Duckbill valve

Duct connector apparatus and method

Dynamic control valve for modifying fluid flow

Easily disassembled, one-way check valve