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# OAR Box 

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# A-94-5 2

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# iv-e- w Chuc k Darvi n Pag e 1 CONTAC T REPOR T Person Calling :

Person Called : Dat e o f Contact : Keit

h Barnet t U.S . Environmenta

l Protectio n Agenc

y OAnps/ESD/MIC G 919-541-560 5 Chuc k Darvi n USEPA/OR

D 919-541-763 3 Decembe r 17 , 200 1 • - - - , \ ' ,• ,

••PAMH - i,u.v i Contac t Summary : I calle dChuc k

t o as k abou t wor k h e ha d don e o n stratificatio n o f P M an d VO C i

n pain t spray booths . Chuc k state dtha t

ther e wer e numerou s report s an d paper s o n th e subject . Som e ofth e wor k was incorporate dint o th e Aerospac e NESHA P for th e filter tes t method . Some report s ar e "Demonstratio n o f Spli t Flo w Ventilatio n and Recirculatio n a s Flo w Reductio n Method s i

n a n Air Forc e Pain t

Spra y Booth" . EP A 600/R-94-214 ao r AL/EQ-TR-1993-0002 . Demonstratio n o f

Pain t Spra y Boot h Emission s Contro l Strateg y usin g Recirculation/Partitionin g and UV/Ozon e Pollutan t

Emissio n Control . EP A 600/R-98-016 a AWMA , Jun e 1993 . Demonstratio n o f Pain t Spra y Boot h Air

Reticulatio n an d Partitioning . 93

- RA-83C.0 3 199 7 AICH E meeting . Pain t Spra y Boot h Desig n usin g Recirculatio n an d Partitionin g Ventilatio n 14 t hAnnua l Arm y Environmenta l Symposium , 1 4 Novembe r 1989 . USATHAMA . Stratificatio n o f Particulat e an dVO C Pollutant s i n Horizonta l Flo w Pain t

Spra y Booths . Environmenta l Progress , Fal l 98/99 . Pain t Spra y Boot h Desig n Usin g Recirculatio n an d Partitioning . Octobe r 1997 . Moder n Paintin g an dCoatin g Chuc k an dI briefly discusse dth e result s o f thes e studies . I n vertical flo w spray booths , th e pollutant s ten dno t

t o defus e laterally . Yo u ca n se e thi s visually b y lookin g at th e pain t overspray , i t tend s t o g o straigh t

down . Diffusio n doe s no t tak e plac e unti l th e flow directio n i s change d (suc h a s ben din th e ducting) . Th e same occur s in horizonta l flo w spray booths . Th e VO C doe s no t diffuse , i t

remain s stratifie d andmove s horizionall y t o th e exhaust . I f th e VO C sourc e i s clos e t o th e exhaust , th e VO C doe sP. 3 Chuc k Darvi n Pag e 2 no t drop , but enter s th e exhaus t

a t th e sam e elevation i

t i s released . The farthe

r awa y th e exhaus t for mth e VOC source , th e mor e i t drops . I asked Chuc

k about th e issu e concernin

g OSH A regulations . Chuc

k sai dtha t i n th e 1970' s OSH A too k a n NFP A regulatio n an

d incorporate di

t int o thei r rules . The NFPA regulatio n say s yo u ca n no t recirculate , but

no t du e t o worke

r exposur e concerns . I t

wa s t o prevent concentration s gettin g hig

h enoug h t o reac h th e lowe r explosive limi

t (LEL) ( e.g. , explosion) . Also , th e regulatio n actuall

y wen t on t o sa y tha t yo u coul drecirculat

e i f monitor s wer

e used to preven t reaching th e LEL . Reaching th e LE L i s no t aconcer n i n pain t spra y operation s due t o th e hig h ai r flow s involved. . OSH A finally agreed tha

t recirculatio n o

f pain t spra y boot h exhaus t wouldb e handledas ad

e minimi s violation unles s th e concentration s exceede dth e saf e level s fo r huma n exposure . A d

e minimi s violation mean s th e violation i s enteredi n th e inspectors' s report , but no action i s necessar y (sinc e th e chang e doe s no t affec t th e spiri t ofth e regulation , i

t i s no t afinable violation ofth e rule) . Reference s suggeste d b

y Chuc k on thi s issue ar

e alette r fromSusa n Wyat t date dJun

e 16 , 1990 , discussin g d e minimi s violations ; Industria l Ventilation , 21t

h edition , Manua

l o f Recommende

d Practices ; OSH

A we b site , OSH

A directiv e 200-67 , Instructio n CP L 2.1 1 Oct

30 , 1978 . Als o get acop y o f NFP A 33 , 199 8 edition . Rea

dthi s rule carefull

y abou t ai r recirculation . (Not

e tha t recirculation i s no t

prohibited unde

r NFP A codes) .