steam quality output is represented at 32 determining the quality of the steam being carried determines what should be done to ensure optimum operation of the system as shown of the oil field in which well head 14 is placed in order to have accurate steam quality measurements it is essential that the density of the steam including both the liquid and vapor phases be determined accurately in many instances where there is condensed water or the like along the sides of the steam pipe in the area where the density measurement instrumentation is positioned the steam quality measurements are erroneous because the liquid and vapor phases are not uniform across the diameter of the pipe various mixers have been advanced but none that provide for low pressure drop and accurate mixing the mixing section 12 of the pipe as shown in fig2 includes an orifice plate 35 that is mounted across the pipe and has an orifice throat or opening 36 in the center thereof the size of the orifice opening 36 is selected so that even at low pressures and velocity the liquid and vapor phases including as well any condensed water or precipitate such as the water indicated at 37 in the lower portion of the throat the pipe is horizontal as shown are carried into the central opening 36 and the velocity of the vapor phase of the steam is increased to a point where the liquid phase and water are broken up into droplets by the shear force of the vapor phase acting against the surface tension of the.