System setup for performing an automated biological methane potential test of a biosample by measuring biomethane gas in a biogas flow, the system setup comprising: - multiple digesters; - multiple containers for chemical fixation of other gases than biomethane gas, the other gases being at least CO 2, wherein the chemical fixation is based on irreversible reaction(s); and - a flow cells array comprising multiple direct gas flow measuring devices; - a data acquisition system (DAQ unit) configured for continuous and in real-time data recording and analyzing of the gas flow measurements; wherein each digester is connected to one container for chemical irreversible fixation which in turn is connected to one gas flow measuring device; wherein each gas flow measuring device is a liquid displacement measuring device having a gas compartment with one gas accumulating end and one lifting end, wherein gas storing capacity of the inside of the gas compartment is larger at the gas accumulating end than at the lifting end, wherein the gas accumulating end has a higher vertical position than the lifting end at an initial standby position, wherein the gas compartment has a triangular cross section perpendicular to a longitudinal direction of the gas compartment, and wherein the liquid displacement measuring device is operating based on leverage effect, wherein each gas flow measuring device is immersed in a wet space, and wherein each liquid displacement measuring device has at least one sensor means provided to generate a signal and/or change the state of a signal when the gas compartment is not in its initial standby position. - multiple digesters; - multiple containers for chemical fixation of other gases than biomethane gas, the other gases being at least CO 2, wherein the chemical fixation is based on irreversible reaction(s); and - a flow cells array comprising multiple direct gas flow measuring devices; - a data acquisition system (DAQ unit) configured for continuous and in real-time data recording and analyzing of the gas flow measurements; wherein each digester is connected to one container for chemical irreversible fixation which in turn is connected to one gas flow measuring device; wherein each gas flow measuring device is a liquid displacement measuring device having a gas compartment with one gas accumulating end and one lifting end, wherein gas storing capacity of the inside of the gas compartment is larger at the gas accumulating end than at the lifting end, wherein the gas accumulating end has a higher vertical position than the lifting end at an initial standby position, wherein the gas compartment has a triangular cross section perpendicular to a longitudinal direction of the gas compartment, and wherein the liquid displacement measuring device is operating based on leverage effect, wherein each gas flow measuring device is immersed in a wet space, and wherein each liquid displacement measuring device has at least one sensor means provided to generate a signal and/or change the state of a signal when the gas compartment is not in its initial standby position. wherein each digester is connected to one container for chemical irreversible fixation which in turn is connected to one gas flow measuring device; wherein each gas flow measuring device is a liquid displacement measuring device having a gas compartment with one gas accumulating end and one lifting end, wherein gas storing capacity of the inside of the gas compartment is larger at the gas accumulating end than at the lifting end, wherein the gas accumulating end has a higher vertical position than the lifting end at an initial standby position, wherein the gas compartment has a triangular cross section perpendicular to a longitudinal direction of the gas compartment, and wherein the liquid displacement measuring device is operating based on leverage effect, wherein each gas flow measuring device is immersed in a wet space, and wherein each liquid displacement measuring device has at least one sensor means provided to generate a signal and/or change the state of a signal when the gas compartment is not in its initial standby position.