Vacuum Insulated Evaporator

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The Vacuum Insulated Evaporator (VIE) is the most advantageous (cf. gas oxygen manifold), economical (has 10 days supply worth) and least labor intensive method to store and distribute medical oxygen to hospitals.

It stores oxygen in a liquid format and thus needs to be extremely robust. It consists of an outer carbon steel shell and an inner stainless steel shell, with a vacuum insulation in between and kept cold (between -160°C to - 180°C as the critical temperature of oxygen is - 118°C). This is to ensure the VIE can withstand the high pressures (7 bar) required to keep oxygen liquid. That is because in the aforementioned temperature range liquid oxygen will boil (boiling point -183C) unless it is compressed.

[edit] Mandatory Safety Features

The VIE must be kept in an open space with no overhead wires (prevent sparking of liquid oxygen), no surrounding drains or trenches (pooled liquid oxygen is combustible) and ringed by a fence of non combustible material.