Valve for large scale irrigation

A valve assembly including a valve body and a non-planar valve head adapted to be fitted to a water supply line,

• wherein:
• the valve head is adapted to reciprocally travel along a longitudinal axis, supported by a shaft longitudinally aligned parallel to a general direction of water flow from the supply line;
• and
• the valve head includes a wall terminating in a peripheral sealing contact surface for sealing engagement with a valve seat in the valve body, the valve seat defining a valve opening that is adapted to be releasably sealed by the valve head and continuous with the supply line when the valve assembly is in an open position, the wall extending inwardly from the peripheral sealing contacting surface toward the shaft,
• wherein:
• the wall is in the form of a skirt and the peripheral sealing contact surface is in the form of a terminal edge that is formed from a downwardly depending edge of the wall;
• the width of the terminal edge corresponds to or is narrower than the wall thickness;
• the valve body has a wide base at its upstream end and a narrower neck at its downstream end;
• the shaft is secured radially relative to the valve body using at least two axially spaced bearing surfaces;
• interposed between the axially spaced bearing surfaces is a spring bias against the open position;
• and
• the valve head is adapted to axially shift toward downstream to an extent that its displacement distance is of a magnitude at least one quarter of the diameter of a valve opening to provide sufficient clearance by the valve head.