Coupler

A coupler, comprising:

• a first housing having an inner section, an outer section and a first passageway extending through said inner and outer sections, an actuator mounted to one of said inner and outer sections within said first passageway;
• a second housing having a first end, a second end opposite said first end, a second passageway extending between said first and second ends, an interior surface defining said second passageway, an exterior surface spaced from said interior surface and a plunger movable within said second passageway between an open position and a closed position, said plunger having a leading end, a first seal mounted to one of said leading end of said plunger and said inner surface of said passageway at said first end of said second housing to create a seal between said leading end of said plunger and said first end of said second housing with said plunger in said closed position, a second seal extending outwardly from said exterior surface of said second housing;
• said inner section of said first housing being moveable along said exterior surface of said second housing from said first end toward said second end thereof, said actuator of said first housing contacting said leading end of said plunger in the course of movement of said first housing relative to said second housing to move said plunger to said open position, said second seal of said second housing contacting and creating a seal with said inner section of said first housing prior to contact between said actuator and said plunger and prior to movement of said plunger to said open position;
• and
• a locking mechanism coupled to said exterior surface of said second housing, said locking mechanism being effective to releasably connect said first housing and said second housing to one another with said plunger in said open position.