added per unit of time can be set to a predeterminable value by alteration which is adapted to the manufacturing tolerance of the volume quantity dispensing unit of a pressure value of the volume quantity dispensing unit this method can also be applied to the volume quantity dispensing unit according to the invention in this case the change in the pressure value by the means 3 calibrates the pressure output signal 8 of the pressure transducer 1 in relation to the volume quantity 5 per unit of time to be dispensed it is preferable to carry out the method according to the invention during the final check of the volume quantity dispensing unit i e prior to dispatch furthermore it is conceivable and possible to use the means 3 to change the pressure value in the feed line 12 to the volume quantity dispensing unit in such a case the means 3 could in particular comprise a screw for constricting the feed line 12 to the volume quantity dispensing unit although only one specific embodiment has been described in detail it will be clear to any person skilled in the art that the pressure sensor signal preferably an electric current or voltage signal is changed in such a way as to eliminate the actual inner pressure value inside the metering unit in which the pressure value which is then actually to be dispensed to a controller is used to compensate for calibrate or change the desired or.