E-cylinder

An e-cylinders is a type of gas cylinder used for storage and containment of gases. In anesthesia, e-cylinders are typically used for delivery of fresh gases to the anesthesia machine in case of pipeline gas pressure failure. E-cylinders uses the pin index safety system (PISS) that ensures the correct placement of cylinders of a particular type of gas into the right location in the anesthesia machine.

Gas	Cylinder Color (USA)	Full Tank Volume (L)	Full Tank Pressure (PSI)
Oxygen	Green	660	2200
Nitrous Oxide	Blue	1590	750
Air	Yellow	625	1800

Unlike other gas cylinders, nitrous oxide is pressurized in liquid form, and therefore the pressure (psi) remains the same up until about 1/4 capacity (~400L).

Physical properties

Diameter	100 mm (4 in)
Height	660 mm (26 in)
Empty weight	6.4 kg (14 lb)
Internal volume (21 °C, 1 atm)	4.5 L (0.16 ft3)