Flow cytometer arrangement comprising ▪ a flow measurement cell , ▪ a mixer , ▪ an incubator , ▪ a first pump , a second pump , a third pump and a fourth pump , ▪ an inlet connection , ▪ a dye reservoir , and ▪ a sheath fluid reservoir , ▪ wherein the first pump is connected on the inlet side to the inlet connection for suction of sample fluid, ▪ wherein the second pump is connected on the inlet side to the dye reservoir for suction of dye, ▪ wherein the first pump and the second pump are connected on the outlet side to the mixer , in order to pump sample fluid and dye into the mixer , and the mixer is designed to mix the sample fluid and the dye to give a mixture, ▪ wherein the fourth pump is connected on the inlet side to the sheath fluid reservoir for suction of sheath fluid, ▪ wherein the third pump is connected on the outlet side to the flow measurement cell in order to produce a sample jet through the flow measurement cell from the mixture, ▪ wherein the fourth pump is connected on the outlet side to the flow measurement cell in order to produce a sheath jet through the flow measurement cell that ensheaths the sample jet from the sheath fluid, ▪ wherein the mixer is connected on the outlet side to the incubator which is connected on the outlet side to the third pump , characterized in that ▪ the flow cytometer arrangement comprises a control device configured to control the pumps , and ▪ the control device is configured to control the first pump and/or the second pump and the third pump in such a way that the third pump sucks in mixture from the incubator , and synchronous operation of the first pump and/or the second pump keeps an operating pressure in the incubator at a specified pressure. ▪ a flow measurement cell , ▪ a mixer , ▪ an incubator , ▪ a first pump , a second pump , a third pump and a fourth pump , ▪ an inlet connection , ▪ a dye reservoir , and ▪ a sheath fluid reservoir , ▪ wherein the first pump is connected on the inlet side to the inlet connection for suction of sample fluid, ▪ wherein the second pump is connected on the inlet side to the dye reservoir for suction of dye, ▪ wherein the first pump and the second pump are connected on the outlet side to the mixer , in order to pump sample fluid and dye into the mixer , and the mixer is designed to mix the sample fluid and the dye to give a mixture, ▪ wherein the fourth pump is connected on the inlet side to the sheath fluid reservoir for suction of sheath fluid, ▪ wherein the third pump is connected on the outlet side to the flow measurement cell in order to produce a sample jet through the flow measurement cell from the mixture, ▪ wherein the fourth pump is connected on the outlet side to the flow measurement cell in order to produce a sheath jet through the flow measurement cell that ensheaths the sample jet from the sheath fluid, ▪ wherein the mixer is connected on the outlet side to the incubator which is connected on the outlet side to the third pump , ▪ the flow cytometer arrangement comprises a control device configured to control the pumps , and ▪ the control device is configured to control the first pump and/or the second pump and the third pump in such a way that the third pump sucks in mixture from the incubator , and synchronous operation of the first pump and/or the second pump keeps an operating pressure in the incubator at a specified pressure. <EOS>