PURPOSE:To simplify a piping system, and to control pressure and heat easily by thermally shielding helium in a pipe between a normal liquid helium vessel and a superfluid helium vessel by one valve while isolating helium under pressurized stage, too. CONSTITUTION:A stepped section is formed on the inside and a valve seat 40 capable of being isolated in a pressure manner is shaped while another heat- shielding valve seat 42 having a tapered shape on the lower side is shaped in the nose of a double valve body 38 for superfluid helium, and a valve body 44, which is unified with a driving rod 43 and corresponds to the valve seat 40 having a pressure isolating function, is mounted slidably into a guide field 39 through guides 45, 46. A valve body 40 having another heat shielding function in which a system 48 is fitted freely into a hole 47 shaped into the valve body 44 is set up in response to the valve seat 42 in an adhesive manner, and an elastic spring 51 is interposed between a flange 50 for the system 48 and the bottom of the hole 47 and the valve body 49 having a pressure isolating function is energized so as to be relatively extended to the valve body 44.
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