Where parts support loads or provide actuating forces and a mechanical fault could create unacceptable risk: the design of any system for support, suspension or actuation rests on the total load and Table 21; accessory attachments cannot be fitted incorrectly in a risky way; the risk analysis considers loading of every kind (static, dynamic, vibration, impact, pressure), movement of foundations, temperature, environment, manufacture and service, and all likely failure effects (excessive deflection, plastic deformation, ductile, brittle and fatigue fracture, buckling, stress corrosion cracking, wear, creep, material deterioration and residual stresses); and the documents give instructions and materials for attachment to floor, wall or ceiling with advice on checking the structure. Support systems keep structural integrity through the expected service life with tensile safety factors not below Table 21 (2.5 or 4 for parts not impaired by wear with 5 percent or more elongation at break, 4 or 6 below 5 percent; 5 or 8 and 8 or 12 for parts impaired by wear such as chains, cables, belts, jack screw nuts, springs and hoses without a mechanical protective device; 2.5 or 4 and 4 or 6 with one; 2.5 or 4 for the protective device itself, case A where strength and forces are accurately known and case B otherwise) unless an alternative method demonstrates integrity, checked against the risk management file, material and processing specifications and, where tests are needed, by gradually applying the total load times the safety factor and holding equilibrium for one minute. Parts supporting or immobilising patients create no unacceptable risk of injury or loosening; the safe working load is the mass of patients or operators plus the accessories intended to be supported, at least 135 kg and 15 kg for adults unless the manufacturer specifies another application, with a lower patient mass marked on the equipment and documented and a higher one documented; the person's mass is distributed as a human body and accessories deployed as in normal use or the worst position; a foot rest takes twice 135 kg or twice the intended person load over 0.1 square metres for one minute without damage or more than 5 degrees permanent deflection; a sitting area takes 60 percent of the patient or operator share, at least 80 kg, centred 60 mm from the edge for one minute without more than 5 degrees permanent deflection; and dynamic loading is tested by dropping the Figure 33 body test mass at the safe working load from 150 mm onto the seat area with no loss of function or structural damage, basic safety and essential performance maintained. A mechanical protective device is required where wear-impaired parts have safety factors that fall between Table 21 rows 3 and 4 and rows 5 and 6, is designed on the total load with row 7 factors and activates before travel is risky, its overtravel calculated; where use can continue after activation, activation is obvious to the operator and reset needs a tool; a single-activation device makes further use impossible until replaced, with the documents calling for service personnel and replacement, and a general warning sign adjacent to it, tested by defeating the primary support so the maximum load falls from the most adverse position without damage to the device; and no device is needed where parts not impaired by wear meet rows 1 and 2 or wear-impaired parts meet rows 3 and 4.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.