A t the Massachusetts Institute of Technology a few years ago, the school wanted to convert basement storage and shops into classrooms. The steam flow noise from a 24 in. (0.6 m) diameter, 200 psig (1380 kPa) steam distribution main carrying approximately 100,000 lb/h (12 600 g/s), subjectively was judged to be excessive for classroom teaching. Sound level measurements confirmed that the noise level was 79 dBA, which is well above the ASHRAE recommendation of about 35 dBA (25 to 30 RC) for classrooms.