Abstract: A vapor compression system includes an indoor heat exchanger, an outdoor heat exchanger, a compressor, a first valve, and a second valve. The compressor has an inlet connected to a suction flow and an exit connected to a discharge flow. The first valve is movable to connect the discharge flow to one of the indoor and outdoor heat exchangers. The second valve is movable to connect the suction flow to one of the indoor and outdoor heat exchangers.

Abstract: The invention provides a joint between two tubes comprising a box at one end of one tube and a pin at one end of the other tube, the pin being provided on its external surface with a threadless zone at its nose serving as a stabbing guide for entry of the pin into the box, a parallel threaded load carrying zone, and an inclined threaded locking and load carrying zone; the box being provided on its inner surface with a parallel threaded load carrying zone, and an inclined threaded locking and load carrying zone, both generally matching and engageable with the corresponding zones of the pin, and an unthreaded stabbing guide zone axially disposed between said parallel load carrying zone and said inclined locking and load carrying zone of the box; the parallel load carrying zone in the box serving as an extension of the stabbing guide provided between the parallel load carrying zone and the inclined locking and load carrying zone for the nose of the pin, and the two threaded zones in the box being so separated th