Sch 1 para 24 Requirements in respect of devices with a measuring function for explosion protection
(1) In so far as they relate to equipment used in explosive atmospheres, devices with a measuring function must be designed and constructed so that they can cope with foreseeable operating requirements and special conditions of use. (2) Where necessary, it must be possible to check the reading accuracy and serviceability of devices with a measuring function. (3) The design of devices with a measuring function must incorporate a safety factor which ensures that the alarm threshold lies far enough outside the explosion or ignition limits of the atmospheres to be registered, or both the explosion and ignition limits, taking into account, in particular, the operating conditions of the installation and possible aberrations in the measuring system.