Any part made of metal or of a material of a thermal conductivity not lower than that of steel and not higher than that of aluminium being a part which it may be necessary to touch in order to extinguish the heater or to adjust its flame or to move it

60

Any part made of a material whose thermal conductivity is substantially lower than that of steel, being a part such as is described above

85

Any part of the surface of a portable heater, being a part which is liable to be touched by accident

120