AAMI ISO 11195:1995 pdf download – Gas mixers for medical use – Stand-alone gas mixers
5 Normal operating conditions
5.1 Normal operating conditions shall be with the gas mixer connected to inlet gas supplies at all pressults anld pIussule uifferentials in the lallye slated by the manufacturer and at any setting of the mixer control with either flow or no-flow conditions.
5.2 The gas mixer shall have an auditory alarm to indicate that the inlet pressure conditions are outside the range of normal operating conditions specified by the manufacturer [see 15.2 p)]. If electrically pow- ered, the alarm signal shall be a medium priority alarm complying with ISO 9703-2. NOTE 2 The gas mixer need not be provided with a high-pressure alarm if the upper limit of the input pressure specified by the manufacturer is higher than the normal maximum pressure provided by a medical gas pipeline. The maximum gas pressure which a medical gas pipeline con- forming with ISO 7396:1987. Non-flammable medical gas pipeline systems, will deliver in normal use is proposed, in the forthcoming new edition, to be 600 kPa.
6 Reverse gas flow
6.1 Means shall be provided so that the reverse flow of gas from each gas inlet to every other shall NOt exceed 10 mI/h 10.0169 kPa /min) under normal operating cunditions or under any single fault con- diun wthich is IIUl alalled. Tesl acculding lu A.3.
6.2 Means shall be provided so that the reverse gas flow from each gas inlet to every other shall not ex- ceed 100 ml/min (10.13 kPa /min) during any single fault condition which is indicated by an alarm. Test according to A.3.
6.3 The manufacturer shall maintain documentation of methods by which compliance with 6.1 and 6.2 has been verified, together with data supporting the val- idity of the methods.
12.1.1.1 The gas mixer shall have an alarm to indi- cate failure of any one gas supply, whether the supply is derived from cylinders or from a pipeline system. This alarm shall be either gas-powered or electrically- powered. If electrically powered, it shall comply with the requirements for a high priority alarm given in ISO 9703-1 and ISO 9703 2. Tho auditory alarm ohall be automatically de activated when the gae supply ie restored.
12.1.1.2 Electrically-powered alarms shall be operat- ive in the case of electrical power failure, except when an electrical power failure alarm is fitted. Means shall be provided for testing the alarm systems.
12.1.1.3 When tested in accordance with A.1. the alarm shall be activated at the gas supply pressure stated by the manufacturer [see 15.1 e)].
14.5 The concentration adjustment control(s) or its surroundings shall be clearly and permanently marked in accordance with ISO 5359 with the name or chemical symbol of the gases being mixed. If colour coding is used in addition to identify the gases, the culuuls shall be in accurdance with ISO 32.