are a result of manufacturing limitations the present invention can be used to minimize the effects of these variations and results in accurate delivery in any type of liquid pump as discussed in the background there is one type of liquid pump with which the present invention is particularly advantageous the miniature piston type pump the piston diaphragm assembly of a miniature pump requires extremely high manufacturing tolerances in order to generate a reproducible dose volume from one pump to the next even with high precision manufacturing a not insignificant variation from one pump to the next of a given design may be present this is less than ideal especially in applications of the pump involving drug delivery or other medicinal applications the present invention provides a simple inexpensive and reliable mechanism and method for minimizing or u201c zeroing out u201d the differences from pump to pump one aspect involves a logic or processor controlled routine that may be thought of as an automatic calibration of the device in a most general sense this involves measuring the volume of a dosage produced by a given pump comparing that dosage to a nominal dosage volume expected for that particular type of pump design and then adjusting the pump output accordingly this can also be accomplished by measuring the flow rate and then adjusting accordingly both volume and flow rate measurement comprise usage of one or more sensors that indicate the presence of.