Specifies general design and performance requirements for analgesic machines of the intermittent flow (demand flow) type for use with 50/50% (V/V) mixture of oxygen and nitrous oxide contained in one cylinder. Applies to analgesic machines which are meant to be used under supervision for the self-administration of an analgesic mixture in response to the patient's inspiratory effort.

This Part of BS4272 specifies general design and performance requirements for analgesic machines of the intermittent flow (demand flow) type for use with 50/50%(V/V) mixture of oxygen and nitrous oxide contained in one cylinder, (hereinafter referred to as \'analgesic machines\'). This standard applies to analgesic machines intended for: connection directly to a high-pressure (approximately 17MPa) cylinder; and connection to a low-pressure (280kPa to 600kPa) supply from a medical gas pipeline system, or a similar source, filled from cylinder(s). Additional requirements for portable machines are included. This standard applies to analgesic machines which are intended to be used under supervision for the self-administration of an analgesic mixture in response to the patient\'s inspiratory effort, e.g. in obstetric practice or in emergency situations. It does not apply to analgesic machines with means to initiate gas flow other than by the patient\'s inspiratory effort. This standard does not give requirements for the composition of the gas mixture, or for the markings on the gas cylinder. NOTE The gas is pre-mixed and specified in pharmacopoeia monographs. The markings on the gas cylinder are specified in BSEN850.