Thermal expansion relief valve

A fluid flow control valve comprising a thermal expansion relief valve for protection against damage due to freezing of fluid in said fluid flow control value,

• said fluid flow control valve comprising:
• a main valve body having a wall with an exterior wall surface exposed to freezing temperatures and an interior wall surface defining a main fluid flow conduit and said wall defining a central region in said main fluid flow conduit spaced from said interior wall surface, and other components,
• said thermal expansion relief valve comprising:
• a relief valve body defining a relief conduit in fluid communication with said main fluid flow conduit, said relief conduit having an inlet located in said central region thereby to delay obstruction of said relief valve conduit by initiation of ice formation upon the interior wall surface and an outlet in fluid communication with a region exterior of said main fluid flow conduit,
• a valve element disposed and adapted for movement within said relief conduit between a first sealing position in engagement with a valve seat to resist fluid flow and a second position spaced from said valve seat to allow fluid flow from the main fluid flow conduit through said relief conduit, and
• means for biasing said valve element toward said first sealing position with a predetermined force representing a threshold pressure selected to exceed normal operating pressure of the fluid flow control valve and selected to lie below pressure damaging to the main valve body and other components.