Pit & Quarry, July 2012
COMMUNITY RELATIONS beep beep tonal sound familiar to narrowband alarms the broadband alarms shhh shhh shhh sound does not contain tones That makes the sound less forceful Apply to mobile equipment Memphis Stone and Gravel has determined that BBS Teks BBS 107 model alarm with a 107 decibel output rating is best suited for its mobile equipment Because the equipment is subject to movement from one location to another the higher output model meets Memphis Stone and Gravels needs The alarm also meets the Mine Safety and Health Administrations requirement of being audible above the surrounding noise levels Field observations as measured with a soundlevel meter showed the alarm to be at the low 90 decible level at about 30 ft away with the machine off and background noise levels at less than 30 decibels About Memphis Stone and Gravel Co Memphis Stone and Gravel Co is an aggregate supplier to West Tennessee and North Mississippi In business since 1910 the company mines sand and gravel deposits at six wash plants It processes a variety of sand products road base materials shoulder gravel clay gravel landscape rock drainage rock and pea gravel A sister company operates asphalt plant facilities Operational background levels inside a typical active pit measure at the 75 to 80 decible level about 25 to 50 ft away from equipment and between 75 and 83 decibels in range of a typical wash plant site The equipment targeted for the BBS 107 was front end loaders dozers graders and haul trucks Operations with sensitive conditions with respect to number of neighbors and property owners impacted by noise were given priority A plan to retrofit old equipment began in late 2005 Since early 2006 the company has installed the alarms on new equipment and to date about 50 to 60 percent of the companys fleet has been converted to broadband alarms Apply to conveyors In addition to using broadband alarms on mobile equipment Memphis Stone and Gravel initiated a pilot project with Brigade Electronics in 2007 to evaluate broadband alarms on its conveyor systems Conventional siren type alarms have historically been safe and effective but again in certain applications there may be a desire to reduce sound Memphis Stone and Gravel for example typically installs field conveyors in 1000 ft segments with entire lengths up to two miles Four to six piggyback conveyors are used to feed materials from the pit to the field conveyor The results of the pilot project led the com 8888014700 0 1u 55 0 T 1 à 999T 55 0 T 1 7 6 61 176 56 174 1 2 6 6 10 9 2 0 17 176 56 1745T 20 PIT QUARRY July 2012 www pitandquarry com
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