a nozzle design for diffusing high pressure steam into by flowing process fluid of substantially lower pressure while reducing the noise intensity generated . the injection nozzles include an opening having a first diameter to receive steam and a second diameter to inject the steam into a flow of liquid . the diameters of the first and second openings can vary relative to each other to enhance the flow characteristics of the steam or other gas being injected into a flow of liquid . the outer surface of a diffuser tube is coated with an insulating material , such as plastic . in alternate embodiments , the orientation of the injection holes can be angled either upstream or downstream to further enhance mixing characteristics of the steam .