A method of controlling at least two pipetting operations out of the group comprising aspirating a liquid dose and dispensing a liquid dose, the method comprising - a first pipetting operation of providing a first pipette with a first working medium at a first pressure having a first sign with respect to a reference pressure , which first sign is negative for said first pipetting operation being aspirating and which first sign is positive for said first pipetting operation being dispensing, wherein an amount of said first working medium flows across a flow restriction in form of a capillary or a micro-channel towards or away from said first pipette, thereby dispensing the liquid dose into a receptacle or aspirating the liquid dose into the first pipette, - a second pipetting operation of providing a second pipette with a second working medium at a second pressure having a second sign with respect to said reference pressure, which second sign is negative for said second pipetting operation being aspirating and which second sign is positive for said second pipetting operation being dispensing, wherein an amount of said second working medium flows across said flow restriction or across a further flow restriction, thereby dispensing the liquid dose into the receptacle or aspirating the liquid dose into the second pipette, - discharging a pressure in said first working medium through a controlled valve arrangement to said reference pressure between said first and said second pipetting operations, wherein said first pipette is said second pipette, or said first and second pipettes are different pipettes, wherein both said first and said second pipetting operation occur through a flow connection in fluid communication with said controlled valve arrangement . - a first pipetting operation of providing a first pipette with a first working medium at a first pressure having a first sign with respect to a reference pressure , which first sign is negative for said first pipetting operation being aspirating and which first sign is positive for said first pipetting operation being dispensing, wherein an amount of said first working medium flows across a flow restriction in form of a capillary or a micro-channel towards or away from said first pipette, thereby dispensing the liquid dose into a receptacle or aspirating the liquid dose into the first pipette, - a second pipetting operation of providing a second pipette with a second working medium at a second pressure having a second sign with respect to said reference pressure, which second sign is negative for said second pipetting operation being aspirating and which second sign is positive for said second pipetting operation being dispensing, wherein an amount of said second working medium flows across said flow restriction or across a further flow restriction, thereby dispensing the liquid dose into the receptacle or aspirating the liquid dose into the second pipette, - discharging a pressure in said first working medium through a controlled valve arrangement to said reference pressure between said first and said second pipetting operations, said first pipette is said second pipette, or said first and second pipettes are different pipettes, wherein both said first and said second pipetting operation occur through a flow connection in fluid communication with said controlled valve arrangement . <EOS>