<P> Source equipment systems are generally required to be monitored by alarm systems at the point of supply for abnormal (high or low) gas pressure in areas such as general ward, operating theatres, ICU / ITU / CCU / NICU, recovery, major treatment rooms, etc . Equipment is connected to the medical gas pipeline system via Station Outlets (US) or Terminal Units (ISO). </P> <P> Medical gas systems are commonly color coded to identify their contents, but as coding systems and requirements (such as those for bottled gas) vary by jurisdiction, the text or labeling is the most reliable guide to the contents . Emergency shut - off valves, or zone valves, are often installed in order to stop gas flowing to an area in the event of fire or substantial leak, as well as for service . Valves may be positioned at the entrance to departments, with access provided via emergency pull - out windows . </P> <P> Oxygen may be used for patients requiring supplemental oxygen via mask . Usually accomplished by a large storage system of liquid oxygen at the hospital which is evaporated into a concentrated oxygen supply, pressures are usually around 345 - 380 kPa (50 - 55 psi), or in the UK and Europe, 4 - 5 bar (approximately 58 - 72 psi). This arrangement is described as a vacuum insulated evaporator (VIE) or bulk tank . In small medical centers with a low patient capacity, oxygen is usually supplied by a manifold of multiple high - pressure cylinders . In areas where a bulk system or high - pressure cylinder manifold is not suitable, oxygen may be supplied by an oxygen concentrator . However, on site production of oxygen is still a relatively new technology . </P> <P> Medical air is compressed air supplied by a special air compressor, through a dryer (in order to maintain correct dewpoint levels), and distributed to patient care areas . In smaller facilities, medical air may also be supplied via high - pressure cylinders . Pressures are maintained around 345 - 380 kPa (50 - 55 psi). </P>

Which gas is used in oxygen cylinder in hospital