of a conventional air in line detector 64 for the detection of air located immediately upstream from valve 62 and connector 54 when the additive feature is not in use it is not necessary to utilize the additive module 28 in this mode of operation control device 26 may be set up with a volume and rate for the primary fluid to which the unit will then control if however a piggyback additive is to be employed the device is assembled as schematically illustrated in fig1 with an additive set in position on the additive module 28 control device 26 is set to control valves 60 and 62 in accordance with the instructions input in the primary and secondary displays 30 and 32 after inputting the desired volumes and rates through pads 34 36 38 and 40 the operator causes the instrument to activate and the control device 26 initially causes primary valve 60 to close and secondary valve 62 to open delivery of fluid will therefore be from the secondary fluid connector 22 through line 52 and line 56 through the control site to the patient if the operator has chosen to enter 34 all 34 in the secondary volume to be delivered display this delivery will continue until the air in line sensor 64 detects the presence of air adjacent the y connector 54 upon such detection the condition.