Siphon Purging
The siphon purging process starts by filling the vessel (e.g. a large storage tank) with liquid, such as water or any other liquid compatible with the product. The purge gas is subsequently added to the vapor space of the vessel as the liquid is drained from the vessel.
When using the siphon purging process, it may be desirable to first fill the vessel with liquid and then use the sweep-through purge process to remove oxygen from the residual head space.
Siphon purging may not be appropriate if the liquid is above its flash point due to evaporation into the space.