A 1.2 m diameter vacuum gate valve has been built by VAT as the first of a
series of four, to equip the 2 x 3 km arms of the VIRGO interferometer. A P
arker viton ring phi = 15 mm, l = 4 m was submitted to a special heat treat
ment in air and in vacuum at Orsay before being inserted into the gate valv
e. The results tests on air tightness and on hydrogen, fluorine, and hydroc
arbon outgassing carried out on the first gate valve are presented. (C) 200
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