The pressure cabin and oxygen systems
Nicholas Green, Steven Gaydos, Hutchison Ewan, Edward Nicol in Handbook of Aviation and Space Medicine, 2019
System: Aircraft converter consists of an insulated container (see Figure 11.1), control valves and connecting pipes.Liquid oxygen (LOX) cooled to −183˚C.Container insulated to prevent excessive warming, evaporation and pressure build-up.Stabilisation of LOX to prevent temperature stratification/uneven delivery usually required, by slight elevation of liquid temperature.
Supply of Medical Gases
Lara Wijayasiri, Kate McCombe, Paul Hatton, David Bogod in The Primary FRCA Structured Oral Examination Study Guide 1, 2017
How is oxygen stored?The main hospital supply of oxygen comes from a vacuum-insulated evaporator (VIE), which holds up to 1500 L of liquid oxygen. This is the most economical and space-saving way of storing oxygen. The liquid oxygen is stored at a temperature between –150 and –170 °C (below its critical temperature of –119 °C) and at a pressure of 7 bar (this is the saturated vapour pressure (SVP) of oxygen at its stored temperature). Because it is in liquid form, oxygen in a VIE behaves like nitrous oxide in a cylinder and therefore in order to know how much oxygen is remaining, the storage vessel rests on a weighing balance so that the mass of liquid oxygen can be measured.The hospital back-up oxygen supply comes from a cylinder manifold (size J cylinders arranged in series), which stores oxygen as a compressed gas at room temperature. The oxygen from these sites gets carried to the hospital in pipelines coloured white delivered at a pressure of 4 bar (400 kPa).Oxygen on the anaesthetic machine is stored as a compressed gas in molybdenum steel cylinders (size E cylinders) with black bodies and white shoulders at a pressure of 137 bar (13 700 kPa).
Bronchopulmonary Dysplasia
Lourdes R. Laraya-Cuasay, Walter T. Hughes in Interstitial Lung Diseases in Children, 2019
Many centers are now discharging BPD infants to home while on supplemental oxygen. Before discharge the infant should be stable on low flow oxygen (no greater than 1 l/min) by nasal cannula for at least 1 week and show an appropriate weight gain. It is helpful for the infant’s primary nurse to make a home visit before discharge to insure that the equipment can be used safely. The medical equipment supplier is contacted by the discharge coordinator and told what equipment the infant will require for home care. The supplier brings the equipment to the hospital and teaches the parent how to use it. On the day of discharge he goes to the home and helps the parents set up the equipment and then provides supplies and service until oxygen therapy is discontinued. We have found liquid oxygen systems to be more convenient than those using compressed gas; portable oxygen packs are also available. The parents are taught to evaluate the infant for cyanosis, tachypnea, and edema and often keep a daily record of the infant’s weight gain. All infants in our home oxygen program are managed jointly by the neonatal follow-up clinic or pediatric pulmonologist and the primary pediatrician. Recently, several centers have begun programs utilizing home ventilators for more seriously affected infants with tracheostomies.
Home oxygen therapy: re-thinking the role of devices
Published in Expert Review of Clinical Pharmacology, 2018
Andrea S. Melani, Piersante Sestini, Paola Rottoli
Liquid oxygen is a gas at ambient temperature, but passes in liquid form at −240°C or less. As approximately one liter of liquid oxygen will produce to 860 l of gaseous oxygen, it offers the advantage to store a larger amount than the gaseous oxygen for a given volume. A reservoir containing 30–40 l of liquid oxygen can last for 8–10 days providing oxygen at a flow rate of 2 lpm. After production liquid oxygen is stored in highly insulated tanks of different size which resemble a thermos bottle. Leaving the reservoir, liquid oxygen warms and immediately vaporizes into gaseous oxygen . As the perfect insulator is not available, evaporative losses can be expected up to 0.5–1 Kg of liquid oxygen per day for each tank even when these devices are not in use. A large stationary tank can easily be used to trans-fill oxygen into portable strollers. The production of liquid oxygen (as well as of gaseous oxygen) is not expansive. However, the supply of liquid oxygen (as well as of gaseous oxygen) requires a distributional network with frequent visits to replace the empty with full tanks. In Italy liquid oxygen is by far the preferred system to deliver LTOT; in our area the average monthly cost of liquid oxygen per person (up to prescription flows of 3–4 lpm for 24 h per day) is about 80–90 €.
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