Closed-case impact sprinklers

摘要

A closed-case impact sprinkler unit having an outer case and an internally positioned riser sleeve that is upwardly extendable into a pop-up position. The riser sleeve may be formed with an external surface that is complimentary to the internal surface of the outer case to prevent the introduction of debris into the interior region of the outer case when the riser sleeve is in a pop-up position. The sprinkler unit may further include a closed-case turret assembly rotatably mounted on the riser sleeve that includes a fluid outlet and a compact impact sprinkler arm. The sprinkler unit may include a dual-stage riser spring assembly to delay deployment of the impact sprinkler arm having a first riser spring that is compressed when a fluid enters the interior region of the outer casing to move the riser sleeve in a relatively upward direction, and a second riser spring that is compressed upon compression of the first riser spring to disengage a valve assembly that permits the flow of fluid and activation of the sprinkler. The invention further provides a trip assembly that includes an elongated actuator opening and a trip pin pivotally mounted within the actuator opening to allow lateral movement of the trip pin which initiates a delayed reversal of the trip assembly upon contact with a trip to provide an extended sprinkling range.