Patent US 8,528,608

A pressure gauge may be coupled to a vessel into which a liquid chemical is to be dispensed. The volume of the vessel may be known and a control device may determine an initial pressure of the vessel using the pressure gauge. A volume of liquid chemical may be dispensed into the vessel which may cause the pressure within the vessel to increase to a second pressure. The control device may determine the second pressure using the pressure gauge may calculate the volume of liquid chemical dispensed into the vessel using the volume of the vessel, the initial pressure of the vessel, and the second pressure of the vessel.