In-line valve

A fluid flow valve comprising:

• a one-piece housing defining a substantially linear fluid flow path, said one-piece housing having a central portion which is coupled on each side to a respective end portion by a deformable segment of said one-piece housing, each of said segments being deformable segment of said one-piece housing, each of said segments being deformable such that said central portion is moveable between said end portions along said substantially linear fluid flow path;
• a poppet attached to one of the said end portions and positioned in said substantially linear fluid flow path such that said central portion abuts said poppet to stop fluid flow through said valve when said central portion is moved toward said one of said end portions;
• a first and second inner sealing sleeves, wherein said end portions of said housing are fixed relative to said inner sealing sleeves, and wherein said central portion of said housing is movable relative to said inner sealing sleeves;
• and
• an outer sleeve surrounding said housing, wherein said inner sealing sleeves are fixed relative to said outer sleeve, and wherein said central portion of said housing is movable relative to said outer sleeve;
• first and second moveable annular pistons, wherein an inner surface of each said moveale annular piston is sealed against an outer surface of each said inner sealing sleeve, and wherein an outer surface of each said moveable annular piston is sealed against an inner surface of said outer sleeve, thereby forming a first air pocket between said first inner sealing sleeve, said first moveable annular piston, and said outer sleeve, and also forming a second air pocket between said second inner sealing sleeve, said second moveable annular piston, and said outer sleeve,
• wherein the outer surface of each said end portions of said housing are sealed against an inner surface of each said inner sealing sleeve, and wherein said central portion of said housing comprises an outwardly extending flange, thereby forming a third air pocket between said first inner sealing sleeve, said first moveable annular piston, said first end portion of said housing, and said outwardly extending flange, and also forming a fourth air pocket between said second inner sealing sleeve, said second moveable annular piston, said second end portion of said housing, and said outwardly extending flange, whereby air in said third and fourth air pockets is substantially sealed from ambient conditions outside said outer sleeve.