NOTE: There is no high negativity float valve. If patient negative pressure in pnuemonectomy space
reaches –13 cm, atmospheric air will be pulled into the system through the small arm of this column.
The patient pressure will be "balanced" between +1 cm (red chamber) and -13 cm (blue chamber). This
helps keep intrapleural pressure at a mean average of -6 cm of H2O, the physiological
"norm".