BS 2456:1973

This British Standard specifies requirements for floats for use for all purposes, including use in cold water feed cisterns and expansion systems for hot water apparatus where they may be exposed to temperatures up to a maximum of 90 °C, comprising plastics spherical floats of 102 mm, 114 mm, 127 mm and 152 mm diameter, and non-spherical floats of equivalent lifting efforts suitable for attachment to the apparatus specified in BS 1212: Parts 1 and 2.