Muffler for Pneumatic Drill. Interim Report.
NTIS: PB/220-372 Available for Reference At Bureau Libraries :81 pages
A need currently exists for more effective noise control in the coal mining industry. In particular, new muffler designs with the required acoustic performance are needed for percussive pneumatic drills. The specific objective of this research was to design and deliver a prototype muffler that would attenuate the air-exhaust noise to 90 decibels on the a scale (90 dba). The test drill used in this study was one used for roof-bolting purposes in coal mines. Using the combined approach analysis by digital-computer program and experiment by simulated-noise tests, three prototype mufflers were designed and constructed at U.S. Steel Research. The mufflers consisted of a variety of resonator chambers and expansion- contraction chambers, and were of the following sizes: 3- by 5-inch elliptical cross section and about 8 inches in length, 5 inches in diameter and about 5 1/2 inches in length, and 5 inches in diameter and about 10 1/2 inches in length. All mufflers in laboratory tests reduced the exhaust-noise level by about 25 dba--from about 115 dba without a muffler to below 90 dba with a muffler.
CP; Final Contract Report;
NTIS Accession No.
NTIS: PB/220-372; Available for Reference At Bureau Libraries
U.S. Steel Engin. & Consul.