In Low Pressure storage, a single insulated pressure vessel is filled to over 90% of its volume with liquid carbon dioxide and maintained at approximately 20baars, and -20℃ by refrigeration.
Units with up to 60 tons capacity are available.
In the Low Pressure system, a central bulk unit normally serves to protect various hazards spread throughout the facility.
Hazard distances of 150 meter or more can be accommodated but, wherever possible, the units are lacated near the hazard, or centrally to a group of hazards.
The refrigeration of the Low Pressure storage units is accomplished by a commercial grade compressor, and refrigeration coil within the vessel near the top.
Its only function is to maintain the pressure 18 to 23 bars.
Failure of this refrieration will cause the pressure to rise slowly.
An alarm system is available to alert personnel to abnormal pressure levels and, if no repairs are made within a reasonable time, the unit will refrigerate itself by bleeding off vapor.
Loss rates for this self refrigeration are very low.