Medical electrical equipment. Particular requirements for basic safety and essential performance of respiratory humidifying equipment|Electrical medical equipment, Oxygen, Protected electrical equipment, Concentrators, Marking, Equipment safety, Medical breathing apparatus, Breathing apparatus, Temperature-rise limit, Inhalation therapy equipment, Performance testing, Gas flow, Sound intensity, Safety measures, Performance, Hazards, Electrical safety, Medical equipment, Accuracy, Strength of materials, Fire safety, Flow measurement