Gas based flow sensor

An apparatus for metered continuous volumetric dispensing of a liquid fluid, the apparatus comprising:

• a pressure control unit;
• and
• a gas supply,
• the gas supply providing a controllable gas stream,
• the pressure control unit comprising an input and an output, wherein the input is configured to be fluidically coupled with the gas supply and wherein the output is configured to be fluidically coupled with an inlet port of a container, the pressure control unit further comprising a first restriction fluidically arranged between the input and the output,
• the pressure control unit further comprising:
• at least one first differential pressure sensor for measuring a pressure difference over the first restriction and the output, the pressure control unit further comprising:
• a bypass line with a bypass valve, the bypass valve is configured to be open or to be closed, wherein the bypass line has a first end connected to the input and has a second end connected to the output, wherein the bypass line is con-figured to provide a direct fluidic connection between the input and the output, when the bypass valve is open.