A chemical vessel is disclosed comprising a dip tube and a level sensor tube arranged in an elongated counterbore incorporated into a housing of the chemical vessel. The chemical vessel may be configured to allow a pushback routine to take place, whereby a level of liquid in the chemical vessel is reduced to a point that the dip tube is free from liquid inside the dip tube or at the bottom of the dip tube. Once the dip tube is free of the liquid, then a vacuum source may be used to purge vapor within the chemical vessel without the risk of damage to the vacuum source.