On all manned platforms and on all unmanned platforms where crews are continuously working on a 24-hour basis, approved type portable fire extinguishers and/or approved type semi-portable fire extinguishers shall be installed and maintained. On all unmanned platforms where crews are not continuously working on a 24-hour basis, approved type portable fire extinguishers and/or approved type semi-portable fire extinguishers are required to be installed and maintained only when crews are working thereon. [CGFR 56-4, 21 FR 903, Feb. 9, 1956]