A medicament preparation system includes a disposable cartridge with a flow path. Various sensors may be placed on the cartridge to measure qualities of the fluid flowing through the flow path. The sensors are placed in precise locations using various approaches that make manufacturing of the cartridge efficient and repeatable. A drain line that is susceptible to fouling may be preattached and various approaches are used to remove or reduce the fouling. An elastomeric contact can also be present in the medical preparation system and used in a conductivity measurement subsystem.