Cascade filling system

In addition, a cascade system is useful as a reservoir to allow a low-capacity compressor to meet the demand of filling several small cylinders in close succession, with longer intermediate periods during which the storage cylinders can be recharged.

In practice, the theoretical transfers can only be achieved if the gases are allowed to reach a temperature equilibrium before disconnection.

Cascade filling is often used for partial pressure blending of breathing gas mixtures for diving, to economize on the relatively expensive oxygen, for nitrox, and the even more expensive helium in trimix or heliox mixtures.

[2] Cascade storage is used at compressed natural gas (CNG) fueling stations.

[citation needed] [4] The storage cylinders may be used independently in sequence using a portable transfer whip with a pressure gauge and manual bleed valve, to transfill the receiving cylinder until the appropriate fill pressure has been reached, or the storage cylinders may be connected to a manifold system and a filling control panel with one or more filling whips.

The storage cylinders may be filled remotely and connected to the manifold by a flexible hose when in use, or maybe permanently connected and refilled by a compressor through a dedicated filling system, which may be automated or manually controlled.