Professional flow limiter equipped with an automatic reduction valve. This enables the extraction of gas from the tank at a constant flow rate, independent of the pressure in the cylinder. Therefore it is possible to comfortably take gas samples even from cylinders with a very low pressure. This is suitable mainly for the analysis of residue gas before blending a new mixture or for precisely measuring a large amount of cylinders with different pressures. Does not include a connection hose, which may be ordered separately.