FREEZE-FRACTURE PREVENTION PLUG AND SELECTOR VALVE- ATTACHED JOINT

摘要

PROBLEM TO BE SOLVED: To provide a freeze-fracture prevention plug and a selector valve- attached joint capable of surely preventing the fracture of an instrument by freezing without incurring the increase of the cost of equipment or an operating cost. SOLUTION: The freeze-fracture prevention plug is constituted of an operating member 80 having a part thereof constituting a valve body 72 for opening and shutting a water passage 73, at the same time, the other part thereof used for an opening and shutting control section 74 for switching an OFF state to open the instrument 60 to the outside to an ON state to close it to the outside and a spring member 33 energizing the operating member 80 to the direction decreasing the inside volume of the instrument 60, and when the water inside of the instrument 60 is frozen to result in volume expansion, the operating member 80 is moved to the outside direction increasing the inside volume of the instrument 60 against the energizing force of the spring member 33, and the rise of inside pressure by volume expansion of water to prevent the fracture of the instrument 60.