Patent ID: 8608699

Claim:
A method for determining the presence of air in a cartridge or infusion tube set comprising: inserting a cartridge into a pump, at least one of the cartridge and an infusion tube set being sealed; moving a cartridge plunger a predetermined distance into the cartridge at a first time; measuring a first pressure in the at least one of the cartridge and the infusion tube set while the cartridge plunger is moved the predetermined distance; and determining the at least one of the cartridge and an infusion tube set contains some amount of air if the pressure measurement is less than a specified pressure, wherein moving the cartridge plunger the predetermined distance includes gradually moving the plunger over a period of time until the predetermined plunger position is reached, and measuring the first pressure in the cartridge and the infusion set tube includes measuring a pressure rate of change in the at least one of cartridge and the infusion tube set over the period of time.