Dispensing assembly and container system including the same

A dispensing assembly for dispensing a first fluid, comprising:

• a first chamber comprising:
• a first volume;
• a bottom with a first opening;
• and
• a first valve sealing the first opening, wherein when the first valve leaves the first opening, the first fluid is allowed to enter or leave the first chamber;
• a second chamber comprising:
• a second volume less than the first volume;
• a second opening sealed by the first valve, wherein when the first valve leaves the second opening, the first chamber is in fluid communication with the second chamber;
• and
• a second valve, wherein when the second valve is open, a second fluid can enter the second chamber;
• a primary piston slidable along a sidewall of the first chamber wherein the second chamber is defined by an internal portion of the primary piston;
• a secondary piston located in the second chamber and slidable along a sidewall of the second chamber;
• a movable piston rod, comprising a lower end is located in the second chamber, the movable piston rod configured to actuate the secondary piston to slide along the sidewall of the second chamber;
• wherein when the first valve leaves the first opening, the second valve is closed as the piston rod actuates the secondary piston to slide downward, and the pressure of the second fluid in the second chamber forces the first valve to leave the second opening so that the second fluid in the second chamber enters the first chamber, thereby allowing the first fluid of a volume corresponding to the second volume to be dispensed out from the first chamber.