Document bB2gVo2qNG9xXe2xL3QwneDZ6

i' __ J8WBBIW41I! LIA15155 t ,t Product Engineering Lead proves a heavy favorite as sound control material Heavy metal, often combined ariOi sound barrier properties of lead to in Wad Uke tome other material*- The pteettc foam end toaetomort, Is helping to meet OfiKA rwquii wwtt sure sound anrmialioa effectiveness of lead/acoustical foam sHo lend* lo bo their products. Many of these enclosure* teU-healing should workmen have to In lectory mechfavery end quieting art made up of panels consisting of dnll hole* to the panel, e g, for sUct/i factory mode products sheet Wad and accoustical polyurethane cal conduit The material encircles tb* foam combination*. Some of the** cable and teed* lo seal potential open- combinations contain more than one inp through which sound could travto. Lead W bm (or blanketing tbs tested sheet of Wad separated by layers of foam The cactoeurt system switt rvguto- comini from noisy machinery, say* (be to enhance sound attenuation proper- tione for fire retaidance and ll W de Lead Industrie* Association ( us ) let over that of aa equal mas* of Wad signed lo meet oa*u standard* depend It is being iMoryorsted is maty prod* to a single sheet. ing on how carefully ll W installed and nets because il offer* exoefleol sound Laad ton sreWm. Typical of such the original noise level* encountered. Insulation properties end Can be tailored machinery enclosure* W a acw modular The system la designed to bring 9$ to meet the various specific demands lor sound control system to ertdoac furni dBA machinery noise sound levels to tow control. ture production machinery developed by 90 dfiA outside the u x u l oasu Rgute* None pollution Is one el (be snow Maher Engineering. Des flames, DW- lions say a worker can perform task* tor tmosjs problems facing Industry today. non. The furniture machinery aoWe ooo- eight hours to a 90 dBA noise environ Statistics show that more than 10% el trol system consist* of 1 Vi-m. thick meit Tbs* compare* to a sound level of the country's working population suffers Wad'foam material; an extruded alu- 115 dBA w vikfe a worker can per some none-eeUtod heartn| impairment msnuni framing system, and flat ahs- form for only 15 mmuta unln* pro and is ha* nts suggested that worker* annum sheets, to gauge* ranging from tected from such no**c levels. They are subjected to the highest industrial soot .04*-tn. to 0*2for the exterior face o high that conversation a impossible. leveh are prone to heart disorders. car- of the panel. According to Maher Engineering, the dilatory and equilibrium problem*. The combination Wad and aomwtkto system can be cuWom-buih to enclose A* tter rrwtt of such problem*, the foam material. produced by the Sound- any type of machinery regardless of sot OccupstiOAaJ Safety and Health Act caw Co^ Brooklyn. N Y . is modular and configuration. The enclosure dw> (o *ma) no* require* that any industry pond system cuoaiatmg of two Vi pd sign features openings at either end to wrth now* level* of more th*a W 4IA (.007g-ta ihcll sheets of lead sand- that stock, input and output can carter must provide hearing centoatioe wahed to acoustical foam. This coro- and Wave the wort station Glass pantos program for Its employees. Thw require bwuiion the* bonded to the backside installed m the side* of the encioauee ment encompamm approximately 40% of the metal extenor and totenoe face permit an unobstructed view of the wort ' i of aQ mduatnal manufacturer*. aAd It panel*. The acoustical foam WlH not being performed and. to addition, al is ei peeled (hat appeotimatety t! i bfl- 'dust out- or ddammatc from the sheet low* visual communication between die boo will be spent so implement the hear l ing conservation program So comply with o *ma regulation*. Mow of dw funds allocated by industry for aow* control wdi be spent for acw products and sywcm* that will dampen, muflW or tosutott machinery noise*. Some typical examples of to use to industrial nosse control tndude * spe cialty designed, sound-insulated furni ture machinery enclosure; * multi ma tmaJ shroud to reduce the sound ci t large otmnfugal compressor by 67%; and lead bonded lo Wed to decfeme (few souno 7f plastic* gnoder/granulator by 15%. law ^u* raw*, oouno miiaasse mo- chinrry< enclosure* arc one method lo control noise from Industrial equipment that originally was considered either too targe to equip with adequate sound con trol. or els* is already installed wvthoto built-to noise control. According lo tu, aa tocrcastog umber of machine! y enclosure manu facturers are taking advantage of tbe Mem was cut by 11% compared to unprotected version to aw china T N 3523.01 "v " '> - ;'*^ -............ ... % '-1 LIA15156 - - v '. 1 *" - ~ ^ v. f I i, V t- l if* 5.' - % Sr > L r, f Jr. I f* V' :A operators. who wear etr plugs or nuf- chmev used so grind or granulate hard match the color of (he tudsnes Each ftrrx. and their supervisor. plastic material* must be controlled machine required about 25 sq. ft. of 2 Pt*rBc p*ue fend. A mryt-and-kad since they produce noise WvcW that art paf ( 312 m duck) sheet lead. A apo UratAfttioe installed by IngenoO-Jta&d'i aa high as U dBA two feet from the dal urethane adhesive was utilized to Centac Products Division, Mayfield. grinder, a level that n in excess of bond (hr sheet kad to the exterior of Kentucky, Achieved a 6?* none re oana allowances. the machines. A mechanic metalled (We duction m eta Ime of 7000 CFM Pack Two none control techniques were sheet Wad The total cost of the labor I aged centrifugal compfesaoev i- uaed considered: shipping (he machines *00 and materials waa $100 per grander, a sSed shroud laminated so combma* miles to the Engineering Industries plant $500 cost savmg over the first met alia boa Iced ' foam *ound barrier to achieve where a none retardant cavity skin uon tocktfwquc teased. the 67 ticcrcxxe aoue. could be installed, or apply:*! sheet lead Sound meter reading* before jistafl^ Bccauae o( its design. the Centac pr^ directly lo them at the plastics pUaL tioo of the lead shod was S4 dBA at duces none only from areas of its main The latter technique was used because two fed from the grander Following in** gean. impe/ler 'ares and gear- it saved more than $3,000 a shipping installation, the count was M dBA, a Type 0*1 pump. None reduction ms pri costs and eliminated 10 to 12 weeks of drop of 24 dccibdv Engineering laduw marily achieved by covering these area*, downtime while the machines were be tries reports that it achieved a noise re located m :he mid section of the anil, ing altered. duction of approximately i5%. mth the multi-layer steel shroud and Several techniques ware tested to de Ptenee end trelne. Lead W also quid lead/ foam combination. termine how the sheet lead could be mg products that Wave the factory sssd The lead foam combination consisted most effectively and economically to- go mto the hands of consumers. One of a I paf ( 0156-m thick) sheet kad stalled m the first lest, sheet lead was such example is a sleek business )(. (be sound bemer sandwiched m an tn chick laminated to the interior face of all Gulfstream II. made by Grumman layer of foam- It waa applied over a hopper walk, underneath portions, and Aerospace Corp. previously sprayed-on undercoat layer the interior of pedestak. stands and Powered by two turbofan enginee that and then the steel shroud was placed coven of one machine The required 20 provide a maximum speed of nearly 600 over the top of the enclosed taction. To hours. mph. the G-U encounters high kiileneky conduct away heat build-up within (he In the second test, ilk outside face of aerodynamic noise, also known as boun shroud, specialty desifnad louvers wars two machines wvre laminated to 15 dary layer nose*. Aerodynamic noise in placed at the bottom and lop of (he hours. The latter sheet lead installation creases with velocity, and this in turn enclosure. technique was faster and Just as effec creates a continual excitation of the Engineering Industries. Inc,, Madi tive as thr first technique and it was fuselage akin. Depending on the air son. Wisconsin, solved a major noise problem and realised a $2500 coal sav inf by installing thin, continuous cast therefore used to attenuate the sound of the three remaining plastics grinding machines. Laminating the sheet Wad to craft'* speed and shape, such boundary layer none can cause extremely high noise inside the crafL i sheet lead to five in-production plastic the exterior of the machine* permitted The combined effect of (he boundary scrap grinder*. Nobe from the ma- the Wad surfaces lo be spray-painted to layer noise and that of the powerful tur- -vj& iiflMhfianaiiiaBMSa % l t &m ''- :-r LIA15157` mUf^tHi^St Mu engines crested is overall nobs Wvd of UO decibels la the untrested cabin. This uncomfortable sound Wvst, which can be detriments) to hearing, compare* to Che nobs of s jet fighter U 1000 feet Despite dm high exterior nobs level, GTummui specification* csibd (or a cabin interior that wae "bring room quin." The company's engineers (bm- ton were (seed with the task of bvb oping a sound control tyetec* to ow* oome nobs problems commos lo afl jet aircraft Grumman'* G-D sound control sys tem incorporates three mmual de mcnti: 1) a barrier bunm the craft's engmo and the cabin interior to block the path of exterior sound; 2) methods to damp interior structure borne sound radiation and isolate engine vibration; 3) a method ho absorb sound htsid* the cabin and prevent ha reverberation. The sound barrier between the *- .. r . 'I tenor akin and the cabin interior head liner was a critical clement in the total sound system. Grumman engineer! se- tecied a multi-material system incorpo rating Wad. Tbs sound barrier, leaded vinyl (lead powder dispersed in vinyl), is sandwiched betweca two layer* ot compressed acoustical (cam and b ss- cured m place by the cabin headlinsr. This installation technique eliminate* the need for fasteners which would have penetrated the leaded vinyl and pro vided a Urge number of routes for nobc to enter the cabin. Another major ad vantage of using leaded vinyl U this form m that it b virtually free-floating, thereby improving ti effectiveness. The weight of the Waded vinyl was increased for forward metions of the aircraft became these areas arc sub jected to higher mob* levels of boundary layer noise at maximum cruise speech mph at 35,000 ft has almost the same urrthanc foam was installed over Che and, in addition, (hr glass enclosed cock free-strram dynamic pressure as the fiberglass before the cabin lining w*a pit is more susceptible to none penetra Tarav at 300 mph at sea trvd). How installed. In addition, a I psf Waded tion. Three weights of Waded vinyl wet* ever. Grumman engineers had a distinct vinyl curtain was suspended behind (he used-! J psf for the cockpit. 0.57 p*f advantage in designing the T*c*v aft cockpit bulkhead to provide addi for the forward section of the cabm, since they had already designed the tional insulation from Che nob* of dtt and 0.21 psf for the mid and rear Mo highly effective sound control system for rear-mounted turbofan*. rions of the cabin. the c-n. Based on this previous expe The nobe insulation n providing Che Another modem vehicle, also from rience and knowledge gained in devel research vehicle operator and M en Grumman, got the k*d treatment too. oping the sound control system, W was gineers with a quid environment for the It's s tracked air cushion train now be easily incorporated into the vehick. test program. During the present phase ing tested as pari of the Ui Depart To insulate the cabin, the rodLi-mate when the vehicle b being tested (or ment of Transportation's plan to de rial nobc insulation system was applied speeds of up to 125 mph, nobe protoo velop high speed railroad vehicW* that n the same manner as the system in lion from the turbofan jets b a primary will provide paaaenger and cargo service stalled in the GuUttrcam II: damping consideration. Later, when the tecood between urban area*. Though different foam was applied to about 50 per cent phase of the tests are underway and in design and function, the racav of the skin area, a 4-in. thickness of low the linear induction motor b used to > o faced the same problem* as that of the density fiberglass was compressed into achieve the vehicle's maximum 300 Gulfstream-fl (o-fi) Business Jet-fur- the 3-in. depth between the frame caps mph speeds, noise will come from teS bofan engine nohe and aerodynamic and a I psf Waded vinyl sandwiched sources--turbofsA engine nobc and related engine nobc (the o-n at 600 between two ri in. thicknesses of poly- boundary layer poise. %it | ; - - ' N-' '' LX A X !? 1 x*rr- ADDmONAL INFORMATION AVAILABLE Far further details or anginaarlng aaektance with woke problem contact load Industriae Association. J-4 "DIRECTORY OF ACOUSTIC SPECIALTIES** A 26-page brochura Including descriptions of various lead bearing elements in sheet, laminated, powder, or bulk form for acoustical purposes and including lists of manufacturers. J-S "INDUSTRIAL NOISE --HOW TO CONTROL IT" Technical data on the causes of industrial noisa and information on methods of controlling IL List of con trol materials available. Graphs. J-9 "LEAD A MAJOR FACTOR IN NEW MACHINERY NOISE SUPPRESSION SYSTEMS" Description of techniques used to lower machinery noise levels with lead and lead composites. Lists ma chines that normally exceed noisa level allowed by the Occupational Safety and Health Administration. Two pagee. J-12 "CONTROLLING SOUND WITH LEAD" Reprint from Building Operating Management covers the applications of lead In reducing vibration and air borne noise. Case studies on three new structures are discussed. Illustrated. Four pages. J-13 "LEAD KEEPS CLASSROOMS QUirr* Reprint from Better Schools describes the application of lead for noise insuletion in a large elementary school. Details of installation. Illustrated. Two pages. J-15 "PRACTICAL APPLICATION OF SHEET LEAD FOR NOtSE BARRIERS" Discusses how the use of various thicknesses of lead bonded to or used in conjunction with other construc tion materials detarmines the Sound Transmission Class (STC) rating of walls and partitions. Distributed by Lead Industries Association, Inc. 292 Madison Avenue e New York. N. Y. 10017 Reortnted Iron* the November. 1973 issue of ProOool Engtoeertne O 5M-11/T3 PRINTED IN US A. ^arsarstawkaaflaWtt-. ^ "l