Yearly: complete the six-monthly routine; for gas container water, foam and powder units and stored pressure water-with-additive and foam units, check operating head or cap threads, vents, strainers or expansion devices (or the locking device of threadless heads), internal tubes and anti-overfill devices, internal cylinder condition and lining, seals, and actuating devices including a sharp cutting edge and sound gaskets; discharge stored pressure water-with-additive and foam extinguishers to confirm function (for stored pressure water containing an anti-corrosion or anti-freeze additive, every third year) and recharge with fresh agent, then leak test the disturbed joints; check wheeled cylinder interiors are clean; and, for all types, confirm the fire hazard has not changed, the extinguisher is the right type, class, size or rating for it, and building alterations have not obstructed access or pushed travel distances past what is required (or restricted movement of wheeled units).
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.