The anesthesia machine receives medical gases from a gas supply; controls the flow of desired gases reducing their pressure, when necessary, to a safe level; vaporizes volatile anesthetics into the final gas mixture; and delivers the gases to a breathing circuit that is connected to the patient's airway 

• Common features of anesthesia machine includes inlet for compressed gases, pressure regulator, fail safe device, flow metre, vaporizer, common gas line and breathing limb with its accessory system 
• Hospital pipeline gas enters the anesthesia machine through the pipeline inlet fittings which is gas-specific Diameter Index Safety System (DISS) threaded body fittings. Inlet for compressed gas cylinder (H & E) is with the Pin Index Safety System (PISS) to safe guard cylinder interchanging and possibility of accidentally placing the incorrect gas. 
• Each cylinder supply source has a pressure-reducing valve known as the cylinder pressure regulator. It reduces the high and variable storage pressure present in a cylinder to a lower, more constant pressure suitable for use in the anesthesia machine. The oxygen cylinder pressure regulator reduces the oxygen cylinder pressure from a high of 2,200 psig to approximately 45 psig. 
• Anesthesia machine is designed to accommodate intermediate pressure and low pressure system has connection with patient. 
• The amount of oxygen in your cylinder can be approximated by identifying the original volume of cylinder and the pressure displayed on the regulator 
• Anesthesia machines are equipped with a fail-safe valve designed to prevent the delivery of hypoxic gas mixtures from the machine in the event of failure of the oxygen supply This safety measure will protect against unrecognized exhaustion of oxygen delivery from a cylinder attached to the anesthesia machine or from a central source. 
• Flowmeters on the anesthesia machine precisely control and measure gas flow to the common gas inlet. Gas flow into the flow meter tube raises a bobbin or ball shaped float. The oxygen flush valve allows direct communication between the oxygen high-pressure circuit and the low-pressure circuit. 
• A vaporizer is an instrument designed to change a liquid anesthetic agent into its vapor and add a controlled amount of this vapor to the fresh gas flow. Volatile anesthetics are liquids at room temperature and atmospheric pressure.