Abstract: Apparatus for determining the velocity of a gas in a gas supply duct is provided. The apparatus comprises a flow nozzle and a pitot tube. The flow nozzle has an inlet opening for receiving the gas and an outlet opening for expelling the gas after it has accelerated through a throat connecting the openings. The throat narrows in a curve from the inlet opening to outlet opening. The nozzle is mounted in the duct coaxially in a fluid-tight relationship therewith, the cross-sectional area of the duct and the cross-sectional area of the inlet opening being substantially identical. The cross-sectional area of the outlet opening is 40 to 60 percent that of the duct. The pitot tube comprises an impact tube and a static tube mounted in parallel through the duct downstream of the nozzle and both bending upstream toward the nozzle parallel to the duct axis. The opening of the impact tube is located in the volume bound by the cross-sectional area of the outlet opening and a distance of up to 6.

Abstract: An apparatus for commingling yarn. The apparatus has an inner body having a yarn passageway with a diameter of about 1/4 inch to 5/16 inch. There are orifices through which a high pressure fluid such as air pass to the yarn passageway. The orifices have a diameter of about 0.060 to 0.80 inches.

Abstract: A muffler (10) for use in conjunction with an interfloor tube and aspirator (20) during the production of multifilament, synthetic yarn is provided. Audible noise which is emitted at the inlet end of the interfloor tube is reduced by up to 10 .DELTA.db(A) through the use of a perforated tube (11), restrictor plate (13) and sound absorbing material (16).