Fire protection sprinkler assembly

A sprinkler assembly, comprising:

• a receiver, comprising:
• an inner surface extending from a proximal end to a distal end, the inner surface tapering inwardly between the proximal end and the distal end to form a shoulder, the inner surface does not increase in inner diameter between the proximal end and the shoulder;
• a stop surface at a distal portion of the shoulder;
• and
• a first thread extending from the stop surface and along the inner surface towards the distal end;
• and
• a sprinkler comprising:
• an internal surface to fluidly couple with the receiver;
• and
• a second thread to engage with the first thread to couple the sprinkler with the receiver, the stop surface limits movement of the sprinkler in a proximal direction relative to the receiver caused by rotation of the first thread with the second thread while the first thread is engaged with the second thread.

A sprinkler fitting, comprising:

• a passageway extending from a proximal end to couple with a pipe to a distal end to couple with a sprinkler, the passageway tapering inwardly between the proximal end and the distal end to form a shoulder, the passageway does not increase in inner diameter between the proximal end and the shoulder;
• a stop surface at a distal portion of the shoulder;
• and
• a first thread extending from the stop surface and along the passageway towards the distal end.