VIETNAMESE STANDARDFirst Review TCVN 3985 : 1999 Acoustics - Allow !le "oise levels t wor#$l ce 1% Sco$e "& 'iel& o' $$lic tio" 1.1 This standard specifies allowable noise levels at workplace being affected by noise at production facilities and agencies. 1.2 This standard is applied to control noise emitted during the process of operation of machinery, equipment and means of production that cause impact on employees. (% St "& r&s cite& TCV !1"#$%& methods for measurements of noise at workplace in production workshops. TCV "&'( $ 1&&" )coustics. *escription and measurement of environmental noise. +uantities and method of measurement. TCV '!&&, 1&&- )coustics. *escription of environmental noise. .ay of obtaining data suitable for using the land. 3% Allow !le "oise levels t wor#$l ce !.1 )llowable noise levels at workplace are assessed by equivalent sound pressure level /hereinafter referred to as sound level0 at all workplaces, throughout work shift /-h0, according to characteristic ), not e1ceeding -"d2), the ma1imum level should not e1ceed 11" d2). !.2 3f the total time e1posed to noise during daytime does not e1ceed, ( hours, the allowable sound level is &# d2) for4 2 hours, the allowable sound level is &" d2)4 1 hour, the allowable sound level is1## d2)4 !# minutes, the allowable sound level is 1#" d2)4 1" minutes, the allowable sound level is 11# d2)4 )nd the ma1imum level shall not e1ceed 11" d2)4 1&&"4 TCV '!&&.5or the remaining time of a working day.2. it should be referred to the levels in )ppendi1 ) and use of anti$noise measures as described in )ppendi1 C. the following standards are used. 7eference is made to guide on noise level measurement /measuring device. it is only e1posed to the sound level of below -# d2). 1&&-. !. quantities and method of measurement0 as stated in )ppendi1 2. . )% Noise level Assess*e"t To measure noise level. !. !. measuring position measurement.( To ensure working conditions.1. TCV !1"#$%&4 TCV "&'(.! )llowable noise level for noise is " d2) less than the values mentioned in 6ection !. &3$ressure level s0 ll "ot e1cee&2 .&3A.or#$l ce E/uiv le"t sou"& Sou"& levels t oct r "4e wit0 ce"tr l 're/ue"c5 . statistics. 7emote monitoring and control chamber without telephone information. laboratories. (. 7emote monitoring and control chamber without telephone information. typing room.67. having noise sources."ot e1cee&i"4 .'! 12" 2"# "## 1### 2### (### -### -" && &2 -' -! %-# %" %%! %' %1 %( %# 1. ". !. 7ooms for mental work. planning. laboratory theory and e1perimental data processing. coordination room. research.ANNE+ A . correctly machine installation room. 5unctional. accounting. and statistics rooms. administrative. )t direct work8 production place 2. computer.I"'or* tive- . design. -# &( -% -2 %# -% '" -! "" %& %2 ''! '" '# '! "% '1 "" "& "( %( '- %" '' "& "( "# (% (" (! . . hours with the following equation. can be do assessed in one of two following ways. where determining the <i) or <i)eq hours Correction part D<i)eq.2 $2 $! $(.! 9ethod of measuring and calculation 2. d2) in a shift is calculated by the following equation. to equivalent sound pressure level in working shift of total equivalent sound pressure levels. 2. /d2)0 # % ' " ( ! 2 1 182 18( $1" 181# $1& $#. 6upposed that.!. T. $ <i) is the sound pressure level.' $1.1<i) 0 i @1 $ *epending on measuring different noise levels during a certain period of time to determine the equivalent sound pressure level <aeqT.2 $' $& $12 $ )dding up each correction part which has been found and the sound pressure level <i).1 /<)eq BC <i)eq0 i @1 . . 2. <)eqT @ n 1#lg / A 1##. .1 :quivalent sound pressure level < aeq. the equivalent sound pressure level <i)eq to define values /<i)eq B D < i)eq 0. Ed2)F :1ample.A$$e"&i1 3 /reference0 Noise 8evels 2. :quivalent sound pressure levels as measured at workplace of a worker in a shift are.se type of measuring device to determine the equivalent sound pressure level < eq. towards the noise source and far away from the measurer at least #. and can analy=e the sound level according to the frequency range octa '!$-### >=." m. <i)eq is the equivalent sound pressure level during the period of time t /hours04 $ D < i)eq is corrected < i)eq for each sound pressure level <i) or equivalent sound pressure level < i)eq as defined during the period of time ti /h0 under the following table.1 9easuring :quipment.here. Time ti. $ 9easuring equipment is set at the mode of measuring equivalent sound pressure level /< eq0 and measured continuously for . at workplace.2 9easuring positions. microphone is placed near to workers? ears. n <)eqT @ 1#lg A 1##. !.2 The equivalent sound pressure level <eq at the range 1 octa has the central frequency '!. D < 1) @ $1" d2) D < 2) @ $12 d2) D< !) @ $#. 1###. 3t will be calculated in the following order as follows.11-2 B1##.hen taking correction values according to the table of corresponding time ti. 2###. 1." d2) /. t1 @ G hour4 t 2 @ 182 hour4 t ! @ % 18( hour. *etermining correction part following the above table." 0 -% d2) Thus."0 @ %".1 /<)eq BC <i)eq0 i @1 @ @ 1#lg /1##. -### >=. this worker works at the equivalent sound pressure level greater than the value limit /-"d2)0 2. n <)eqT @ 1#lg A 1##."##. *etermining the equivalent sound pressure level in shift <)eqT. 2. Calculating values /<i) B D<i)0. 2"#. the appro1imate value of ti may be taken$ as selecting the most recent time as in the table or the average value0. . d2) < 1) B D < 1) @ 1## B /$1"0 @ -" d2) < 2) B D < 2) @ &( B /$120 @ -2$ < !) B D< !) @ %" B /$#. 12"." $ (.11-" B1##.!.<1)eq @ 1## d2) for G hour of work shift <2)eq @ &( d2) for 182 hour of work shift <!)eq @ %" d2) for remaining time *etermination of the equivalent sound pressure level in work shift. (###. if value ti does not e1ist.11%(. d2) according to the following equation. isolation.2 Those who work in areas with high noise over -" d2) or time e1posed to noise e1ceeds the limits as specified in )rticle !. • • • C. for e1ample. . • Technical measures. 9easures of construction acoustics. production design and operation of equipment as well as the process of organi=ing workplaces /especially newly constructed facilities0. using sound for sound insulation materials. reducing the time duration of e1posure to noise. equipment manufacturing with low sound capacity.A$$e"&i1 C /3nformative0 A"ti-"oise *e sures C. sound absorption materials.1 must be provided and must use labor protection equipment and must be checked for deaf disease on annual basis. setting up a new technology process. using the technology process with low noise level.4 6uitable working and entertainment regime. for e1ample.1 *uring the process of designing new machines. industrial design. it need to apply measures to prevent and reduce noise at workplace so that it does not e1ceed the permissible level. isolation of noise source. 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