15.1.1 Each unit should carry an appropriate portable
atmosphere testing instrument or instrumentsfootnote. As a minimum, these should be capable of measuring
concentrations of oxygen, flammable gases or vapours, hydrogen sulphide and carbon
monoxide prior to entry into enclosed spacesfootnote. Instruments carried under other requirements may satisfy
this regulation. Suitable means should be provided for the calibration of all such
instruments.
15.1.2 Such instruments should be in addition to those
provided with the unit's firemen's outfits.