6.4.1 Any convenient material of construction that is available as welded or seamless pipe may be used for the construction of the fabricated nozzle. Stainless steel is preferred because of its corrosion resistance and ease of welding. Copper and steel are also used successfully.
6.4.2 Formed Nozzle—Nozzles formed from tubing may be used only when they duplicate the size and shape (rectangular orifice and taper), and the sand flow characteristics (flow rate and streamlined flow) of the fabricated nozzle. (See Fig. 7 and Fig. 9.)
6.4.3 Sand Flow—The nozzle must produce a sand flow rate of 300 to 400 g/min (0.66 to 0.88 lb/min).
6.4.4 Sand Curtain—Fig. 9 shows the proper stream-lined flow and the narrow shape of the sand curtain as it exits from the sand nozzle. A turbulent sand flow as depicted in Fig. 10 will tend to produce low and inconsistent test results. It is intended that the sand flows in a streamlined manner and passes between the specimen and rubber wheel.