Valve assembly

A valve body configured to be positioned for opening and closing of a fluid passage therethrough, said valve body comprising:

• a first element having at least one fluid passage extending therethrough and having an opening at a first surface thereof;
• a second element moveable with respect to said opening at said first surface of said first element, said second element movable away from or toward said first element;
• a third element having a thickness and positioned between said first element and said second element, said third element not physically rigidly connected to either said first element or said second element, said third element not constrained to move away from or toward said first element when said second element is positioned away from said first element by a distance greater than said thickness of said third element, said third element preventing fluid flow through said at least one fluid passage when said second element is positioned away from said first element by a distance equal to said thickness of said third element;
• a guide element disposed adjacent to said second element, wherein said guide element and said second element comprise complementary surfaces which constrain said second element to move only away from or toward said first element, and wherein said guide element comprises:
• an outer diameter adjacent to, and spaced from, an adjacent surface of said second element, and said third element extends around said guide element and comprises an inner diameter greater than said outer diameter of said guide element;
• and
• a mechanical biasing element configured to urge said second element in a direction of said first element, wherein said valve body has a position wherein said third element is not contacted by said mechanical biasing element.