ON EACH WINDOW A SPECIAL HIGH RESISTANCE PLATE REFLEX GLASS IS FITTED WITH SEALING JOINT AND METAL COVER PLATES HOLD BY BOLTS AND NUTS. THE CHAMBER IS CONNECTED TO VESSEL WITH CROSS FITTINGS AND FLANGED, THREADED OR WELDED ENDS. USUALLY, BETWEEN THE INSTRUMENT AND ITS CONNECTING ENDS, VALVES ARE FITTED TO CONSENT SHUT-OFF PIPING AND TO DISASSEMBLE THE LEVEL GAUGE WITHOUT EMPTYING THE VESSEL. DRAIN VALVES CAN ALSO BE FITTED TO CROSS FITTINGS DEVICE.