applicability:
low temperature ball valve are mainly used in the chemical equipment of etylen and LNG etc.to handle low temperature liquid meddium like ethylene,liquid oxygen,liquidhydrogen and so on .these types of iflammable and explosive medium can be volumetrically expanded by several hundred times when being gasifid under temperature rise,and are diffcult to manufacture due to their highly penetrative and leaky properties.
structural properties:
1,the materials of compression parts can endure the expansion and shrinkage resulted from the temperature variation of medium,and seal structure is away from permanent deformation under temperature changs. to work under the conditions below -100℃,the parts of valve shall be subject to deep cooling treatment before precision machining.namely,have the parts cooled inliquid nitrogen box,when he temperature of parts raches -196℃,keep the temperature for 1-2h,then take them out to have them to the normal temperature naturally,and do in this way twice.
2,low temperature ball valve takes a structure to avoid abnormal pressure rise.as the medium in low temperature valve is gasified and rapidly expanded in volume,the pressure will goes extremly high.when the pressur in the middle cavity of valve tises,the midle cavity and the inlet side can be communicated,or a relief can be mounted at the inlet side of valve,thus to ensure th safe use of valve.
