Weld ring: available in carbon steel or light aluminium alloy fixed by wiring ring, height 90 mm.
Fill hole in light Aluminium alloy, pressure balanced design with galvanized iron quick closure. The fill hole cover is kept in its closed
cover: position by a spring, that enables the cover to automatically open at 300 mbar to vent the over-pressure (126 cm2 equivalent to 125 (5″) cross section).
internal breather vent.