The Explosion Hazard Research of the Polyethylene Dust

T ansac ions o he VSB - Technical Uni e si y o Os a a Sa e y Enginee ing Se ies, ISSN 1805-3238 Vol. XV, No. 1, 2020 8 THE EXPLOSION HAZARD RESEARCH OF THE POLYETHYLENE DUST Ma ina SKLENÁROVÁ1, Pe ŠTROCH2, Aleš BERNATÍK3 1 VSB - Technical Uni e si y o Os a a, Facul y o Sa e y Enginee ing, Os a a, Czech Republic and SLOVNAFT,a.s., B a isla a, Slo ak Republic, [email p o ec ed] 2 VSB - Technical Uni e si y o Os a a, Facul y o Sa e y Enginee ing, Os a a, Czech Republic, RSBP spol. s .o., Os a a, Czech Republic, [email p o ec ed] 3 VSB - Technical Uni e si y o Os a a, Facul y o Sa e y Enginee ing, Os a a, Czech Republic, [email p o ec ed] Abs ac : The aim o he a icle is o poin ou he dange s a ising om he p ope ies o plas ic dus and wha in luence i s p ope ies ha e on he o igin and cou se o he explosion. The p esen p ojec analyzed he sample o polye hylene dus ,by-p oduc o g anula e p oduc ion and s o age. The explosion es s we e pe o med on con aine s o a simila shape o hose ound in a plan s. By examining he p ope ies o plas ic dus and i s beha io in he e en o an explosion we ha e obse ed ha he isk o explosion in echnological equipmen can no be unde es ima ed. Knowledge abou explosi eness o dus samples will be used in comp ehensi e sa e y solu ion o a pa icula echnological node. Keywo ds: Polye hylene dus , Maximum explosion p essu e, Maximum a e o p essu e ise, Cons an o dus s, Flame olume. Resea ch a icle In oduc ion The dus consis s o solid pa icles smalle han 0.5 mm. Fo ibe s, he ibe leng h can be g ea e han 0.5 mm. Some a ypical ma e ials can beha e like dus s e en wi h la ge pa icle sizes. The e m dus hus includes g ound solids e e ed o as powde , lou , ibe agmen s and he like (O líko á and Š och, 1999). Dus is conside ed explosi e i , a e igni ion o a mix u e o dus and ai wi h a sui able sou ce, he lame sp eads in combina ion wi h an inc ease in p essu e (Ba knech , 2011). The basic condi ion o he occu ence o an explosion is a subs ance wi h i s p ope ies, which ep esen s he dange o an explosion. Fac o s esponsible o he occu ence as well as o he sp ead o he explosion en e his condi ion. Rele an p ope ies o dus s a e gi en by i e- echnical cha ac e is ics, a e de e mined expe imen ally in labo a o ies and a e no physical cons an s (Damec, 2005), he e o e he gi en subs ance may no show he same alues o i e- echnical cha ac e is ics i i is p oduced and p ocessed in di e en pa s echnological equipmen and unde di e en ope a ing condi ions. In o de o assess he dange o explosion o plas ic dus , a pa o he echnology was selec ed, in which plas ic g anula e is anspo ed and s o ed oge he wi h he dus . The subjec o he in es iga ion was dus , which is a by-p oduc o he p oduc ion and s o age o g anules. The explosion haza d esea ch was based on es ing samples o polye hylene dus and hus ob ain explosion cha ac e is ics o dus , hei espec i e p ope ies. Combus ible dus is only capable o explosion o a limi ed ex en , gi en he lowe (LEL) and uppe (UEL) explosion limi s. Explosion limi s a e he i s o wa n o an imminen dange . The lowe explosion limi cha ac e izes he deg ee o dange o explosi e dus s in p oduc ion p ocesses (O líko á and Š och, 1999). The maximum explosion p essu e pmax ep esen s he maximum alue o he inc eased p essu e gene a ed in a closed con aine by he explosion o an explosi e a mosphe e unde he speci ied es condi ions and unde no mal a mosphe ic condi ions. I is ac ually he maximum alue o he explosion p essu e pmax de e mined by es s in he ange o explosion o dus concen a ion (STN EN 14034-1 + A1 (38 9684), 2011). pp. 8-14, DOI 10.35182/ ses-2020-0002 T ansac ions o he VSB - Technical Uni e si y o Os a a Sa e y Enginee ing Se ies, ISSN 1805-3238 Vol. XV, No. 1, 2020 9 The maximum a e o p essu e ise (dp/d )max is he maximum alue o p essu e inc ease pe uni ime du ing explosions o all explosi e a mosphe es in he ange o explosion o lammable subs ance in a closed con aine unde speci ied es condi ions (STN EN 14034-2 + A1 (38 9684), 2011). Acco ding o he alues o he cons an o dus s, combus ible dus s a e classi ied in o h ee dus explosion classes: • S 1 has KS alues 0 - 200 ba .m/s; • S 2 has KS alues o 200 - 300 ba .m/s; • S 3 has KS alues abo e 300 ba .m/s (Ba lo á and Damec, 2002). The educed explosion p essu e p ed is he p essu e c ea ed by he explosion o an explosi e a mosphe e in a con aine p o ec ed ei he by he de ona ion o he explosion o by he supp ession o he explosion (Damec, 2005). The concen a ion o he explosi e mix u e a ec s he alues o pmax and (dp/d )max. Wi h inc easing concen a ion, he maximum explosion p essu e and he maximum a e o p essu e ise inc ease (Eckho , 2003). Wi h dec easing pa icle size: • he maximum explosion p essu e inc eases (STN EN 14034-1 + A1 (38 9684), 2011), • he limi oxygen concen a ion dec eases (STN EN 14034-4 + A1 (38 9684), 2011; Pang e al., 2019), • he maximum a e o p essu e ise du ing an explosion inc eases (STN EN 14034-2 + A1 (38 9684), 2012). The o ce and eloci y o he explosion inc eases wi h inc easing deg ee o ineness o he ma e ial. The eac ion a e inc eases wi h empe a u e (Damec, 2005). P essu e educ ion educes maximum explosion pa ame e s (Ba knech , 2011). Wi h inc easing ini ia ion ene gy, he maximum a e o p essu e ise also inc eases (Damec, 2005). Wi h inc easing con aine olume: • he maximum explosion p essu e does no change, • he a e o p essu e ise dec eases. Howe e , his law applies o dus -ai mix u es om 40 L. This law does no apply o oblong essels and pipes. (Ba lo á and Damec, 2002). The maximum explosion p essu e in closed, almos sphe ical essels o su icien size (V ≥ 20 L) is independen o he olume. Howe e , he maximum p essu e inc ease depends on he olume. I dec eases wi h inc easing olume in acco dance wi h cubic law. The KS alue esul ing om his law is speci ic o he dus and es me hod, bu is independen o he essel size o olumes V ≥ 20 L (Ba knech , 2011). Ma e ial and me hods The la ge-scale explosion es s was based on esul s o he labo a o y measu emen s. The polye hylene dus samples we e aken om bigbags, whe e dus om dedus ing and s o age silos o he polye hylene g anula e is s o ed. Only 1 sample polye hylene dus was used o u he measu emen s in big olume. The chosen sample had he highes explosion pa ame e s in labo a o y measu emen . Two es essels wi h di e en olumes, a essel o 1.35 m3 (N1) and a essel o 5.45 m3 (N2), we e used o es he dus o PE sample in la ge-scale explosion es s. The essels we e equipped wi h mul ipoin measu emen s o explosion p essu e. The dus was weighed and pou ed in o sp eading anks wi h a olume o 5.4 L a 12 L, which we e p essu ized o 20 ba wi h ai , sp eading nozzles we e used o sp eading. Due o clogging o he sp eading nozzles, he me hod had o be modi ied du ing he es s and he nozzles had o be emo ed om he es essels. A e agi a ion, he mix u e was ini ia ed wi h ene gy om py o echnic ini ia o s wi h an ene gy o 5 kJ each (Jankůj and Be na ík, 2018). Fo es ing, a en ing a ea was ins alled on he uppe langes o he essels, a en ing a ea DN 250 was used on N1 and wo dimensions we e used on N2 - he en ing a ea DN 585 o DN 775. The pipes wi h nominal diame e DN 150 and leng hs o 3, 6 and 10 m we e inco po a ed in o he es se -up. All es s we e pe o med a ambien condi ions, ba ome ic p essu e and ambien empe a u e. A p essu e measu ing se om Kis le was used, he s o age o measu ed alues was ensu ed by means o a C onos FLEX da a logge om IMC. The es s we e eco ded using wo high-speed came as. Resul s Sample o polye hylene dus was es ed in la ge- scale explosion es s and ials. The basic i e- echnical cha ac e is ics was ob ained om he labo a o y es ing which a e summa ized in he ab. 1. pp. 8-14, DOI 10.35182/ ses-2020-0002 T ansac ions o he VSB - Technical Uni e si y o Os a a Sa e y Enginee ing Se ies, ISSN 1805-3238 Vol. XV, No. 1, 2020 10 alues such as alues ob ained om labo a o y measu emen s. By ins alling en ing a ea on he essels, we ha e become con inced ha explosion-p oo measu es in he o m o en ing a ea a e impo an . In he e en o an explosion and he opening o he en ing a ea a he same ime, he de ice will be less s essed by he explosion p essu e. The p oposed en ing a ea can achie e explosion con ol and hus p e en damage o he de ice, aking in o accoun he exis ing p essu e esis ance o he de ice. Explosion es s wi h ins alled piping The aim o hese es s was o measu e and o ob ain o he alues o he maximum educed explosion p essu e in he essel, he pipes and he lame eloci y ex and o e i y he in luence o he ins alled pipes on hei change. Pipes DN 150 wi h leng hs o 3, 6 and 10 m we e ins alled on es essels N1 and N2: • he i s ype o es s was o de e mine he e ec o he leng h o he ins alled piping sys em on p ed wi hou ins alling a en ing a ea on he essel, • in he second ype o es s, a en ing a ea was ins alled on op o he explosion essel. The pe o med measu emen s show ha wi h he leng h o he ins alled pipeline, he explosion p essu e inc eases sligh ly (a he same poin , o example 3 m, bu a di e en leng hs o pipeline). F om a p ac ical poin o iew, his indica es he need o p o ec hese pa s o he echnological equipmen as well as he ad e se e ec s o he explosion. Explosion es s in connec ed essels The aim o he es s was o es he possible ansmission o he explosion and o de e mine he lame eloci y ex in he pipeline and he p essu e alues o he explosion. The es s we e pe o med on essels N1 and N2 wi h a en ing a ea ins alled a he op o he essel, in e connec ed by pipes wi h a diame e o DN 150 and a leng h o 3, 6, 10 m. The dus -ai mix u e was o med in bo h essels, wi h he ini ia ion o he agi a ed dus aking place in only one o he essels. The ansmission o he explosion was sol ed in bo h di ec ions. La ge-scale explosion es s The ollowing ypes o la ge-scale explosion es s we e pe o med o PE sample: • maximum explosion p essu e pmax, cons an o dus s Kmax and maximum a e o p essu e ise in a closed essel (dp/d )max, • educed explosion p essu e, educed a e o p essu e ise (dp/d ) ed and lame eloci y in essels wi h a en ing a ea and wi h a pipeline connec ion. Maximum explosion p essu e and educed explosion p essu e The aim was o de e mine he maximum explosion p essu e and he maximum educed explosion p essu e on con aine s o a simila shape o hose in he plan o he p oduc ion o plas ic g anules and o compa e hem wi h he esul s ob ained in labo a o y es ing. The in en ion was also o es and e i y he e ec o he ins alled an i-explosion measu e on he essel ( en ing a ea on he essels) on he change o explosion p essu e. The measu emen s we e pe o med a an op imal dus concen a ion o 750 g/m3, which was based on he labo a o y de e mina ion o pmax. To de e mine he maximum explosion p essu e and he cons an o dus s PE sample, es s we e pe o med in closed essels (N1 and N2) wi h a olume o N1 = 1.35 m3 and N2 = 5.45 m3. The educed explosion p essu e was measu ed on essel N1 wi h a en ing a ea DN 250, as well as on essel N2 wi h a en ing a ea DN 585 o DN 775 ins alled on he uppe langes o he essels. An e en lowe educed explosion p essu e was achie ed h ough he la ge en ing a ea. The aim was o ge unde he p essu e esis ance o he equipmen in ope a ion. The esul s om he measu emen s o he la ge- scale PE es s a e summa ized in he ab. 2. By measu ing he explosion p essu es on la ge essels N1 and N2, i was ound ha pmax and KS on equipmen o la ge olumes each highe alues compa ed o equipmen in he labo a o y, om which i can be concluded ha he explosion p essu e in ope a ion equipmen is likely o each highe Tab. 1 P e iew o explosion pa ame es PE sample in he labo a o y measu emen s Sample Medium size g ain [mm] LEL ± 10% [g/m3] pmax ± 10% [ba ] KS ± 20% [ba .m.s-1] (dp/d )max ± 20% [ba /s] E1 < MIE < E2 [mJ] Es [mJ] LOC ± 1% [% obj.] PE sample 3> 1 20.00 6.40 68.00 251 30 < 100 80 < 14.00 pp. 8-14, DOI 10.35182/ ses-2020-0002 T ansac ions o he VSB - Technical Uni e si y o Os a a Sa e y Enginee ing Se ies, ISSN 1805-3238 Vol. XV, No. 1, 2020 11 Tab. 2 Explosion pa ame es PE sample measu ed in essels N1, N2 wi h pipes o leng h 3, 6, 10 m No. Type o de ice Pipe leng h [m] Type o de ice pmax [ba ] (dp/d ) [ba /s] p ed in N1 [ba ] p ed in N2 [ba ] p ed in pipe [ba ] ex [m/s] in leng h 3 m in leng h 6 m in leng h 10 m 1. VA 20 au ocla e X 6.400 251.00 X 2. N1 X 7.170 74.201 X 3. N1 DN 250 X 108.587 0.440 X 4. N1 3 X 90.490 2.185 X 0.275 - - 71.5 6 2.175 0.640 0.210 - 111.5 10 2.470 - 1.150 0.620 207.0 5. N1 DN 250 3 X 99.548 0.340 X 0.020 - - 57.3 6 0.365 0.305 0.020 - 117.5 10 0.396 - 0.396 0.080 144.0 6. N1 DN 250 ini ia ion 3 N2 DN 775 X 171.930 (N1) 229.133 (N2) 0.985 0.459 0.441 - - 35.5 6 0.528 0.281 - 0.263 - 38.0 10 0.300 0.239 - - 0.255 36.0 7. N2 X 7.140 75.620 X 8. N2 DN 585 X 160.905 X 0.660 X 9. N2 DN 775 X 138.731 0.190 X 10. N2 3 X 65.385 X 4.525 1.385 - - 262.0 6 4.615 2.210 1.390 - 267.5 10 4.805 - 1.790 1.185 267.5 11. N2 DN 775 3 X 135.320 X 0.185 0.013 - - 205.0 6 0.170 0.160 0.014 - 132.5 10 0.150 - 0.140 0.013 116.5 12. N1 DN 250 3 N2 DN 775 ini ia ion X 152.377(N2) 159.261(N1) 0.865 0.225 0.590 - - 43.5 6 1.002 0.205 - 0.855 - 44.5 10 0.888 0.218 - - 0.133 63.0 Legend o ab. 2: p ed measu ed on N 1 o N 2; p ed measu ed on pipe len g h 3 m; p ed measu ed on pipe leng h 6 m; p ed measu ed on pipe leng h 10 m; Designa ion o he essel wi h he i s ini ia ion and he di ec ion o he sp ead o he explosion.  pp. 8-14, DOI 10.35182/ ses-2020-0002 T ansac ions o he VSB - Technical Uni e si y o Os a a Sa e y Enginee ing Se ies, ISSN 1805-3238 Vol. XV, No. 1, 2020 12 Fig. 1 Example o lame ans e in essels connec ed by piping du ing explosion es s Ini ializa ion was i s pe o med on essel N1 and he explosion was ans e ed ia pipeline o essel N2, whe e a p essu e d op was obse ed. Subsequen ly, he opposi e possibili y was es ed, in which he ini ia ion was pe o med on essel N2 and he explosion was ans e ed ia a pipeline o essel N1, whe e an inc ease in p essu e was obse ed. The lame eloci y, he on o he lame was always measu ed om he essel on which he i s ini ia ion was pe o med. Explosion es s wi h connec ed essels ha e shown ha he p opaga ion o an explosion om essel N2 (la ge olume) o essel N1 (smalle olume) leads o a signi ican inc ease in educed explosion p essu e, despi e he ins alled en ing a ea on bo h essels. The lame ans e in essels connec ed by piping du ing explosion es is shown in ig. 1. In his es ing, we ha e come o he conclusion ha he ins alla ion o en ing a ea, as a o m o explosion p o ec ion, will no be qui e su icien and o he elemen s will ha e o be used o ensu e su icien explosion p o ec ion.  VA20 N1 N1 DN250 N1+ 3mpipe N1DN250+ 3mpipe N1DN250+ 3mpipe p edinN1 N1DN250+ 3mpipe p edinN1 N1+ 6mpipe N1DN250 +6mpipe N1DN250+ 6mpipe p edinN1 N1DN250+ 6mpipe p edinN1 N1+ 10mpipe N1DN250 +10mpipe N1DN250+ 10mpipe p edinN1 N1DN250+ 10mpipe p edinN1 N2 N2DN775 N2+ 3mpipe N2DN775 +3mpipe N2DN775+ 3mpipe p edinN2 N2DN775+ 3mpipe p edinN2 N2+ 6mpipe N2DN775 +6mpipe N2DN775+ 6mpipe p edinN2 N2DN775+ 6mpipe p edinN2 N2+ 10mpipe N2DN775+ 10mpipe N2DN775+ 10mpipe p edinN2 N2DN775+ 10mpipe p edinN2 0 1 2 3 4 5 6 7 8 CLOSEDVESSEL VESSELWITHVENTINGAREA CONNECTEDVESSELSWITH VENTINGAREA‐ INITIATIONIN N1 CONNECTEDVESSELSWITH VENTINGAREA‐ INITIATIONIN N2 EXPLOSIONPRESSURE(ba ) Fig. 2 Compa ison o alues o he explossion p essu e ( om ab. 2) in di e en essels pp. 8-14, DOI 10.35182/ ses-2020-0002 T ansac ions o he VSB - Technical Uni e si y o Os a a Sa e y Enginee ing Se ies, ISSN 1805-3238 Vol. XV, No. 1, 2020 13 Conclusion and discussion The i e- echnical cha ac e is ics o subs ances, which ep esen hei p ope ies, can be d awn om he li e a u e, bu hese alues a e mos ly indica i e, because hey depend on se e al condi ions such as mois u e con en , size, shape o dus pa icles, bu h ough esea ch we ealized how hei beha io a ies depending on ope a ing condi ions. Unde es ima ing his s ep can lead o inco ec de e mina ion o he dange o explosion and hus o unde es ima ion o an i-explosion measu es. Th ough esea ch, we ha e wo ked on he speci ic p ope ies and beha io o PE dus no only in labo a o y condi ions, bu also in la ge- scale es s. La ge-scale es s simula ed he eal design o he gi en echnological equipmen , in which selec ed dus samples a e loca ed. Selec ed condi ions o he cou se o he explosion, such as olume, shape, a angemen o essels, u bulence, we e in es iga ed. We ound ha : • Some samples con ained pa icles o di e en sizes. E en e y small pa icles (less han 0.5 mm), bu also pa icles la ge han 1 mm and a e a he a ypical, ib ous ma e ials and beha e like dus s. • The i e- echnical cha ac e is ics o pmax and KS on equipmen o la ge olumes each highe alues compa ed o equipmen in he labo a o y, he explosion p essu e in he equipmen o he plan is o each highe alues han he alues ob ained om labo a o y measu emen s. • Based on he cons an o dus s, samples o PE dus can be classi ied in class S 1 wi h alues up o 200 ba .m/s. The u bulence was e iden in la ge-scale es s causing inc eases o he a e o p essu e ise and i a ec s he alues o maximum explosion pa ame e s. • The p oposed en ing a ea can be used o achie e explosion con ol and hus p e en damage o he equipmen , aking in o accoun he exis ing p essu e esis ance o he equipmen . • Piping sys ems connec ed o echnological equipmen mus also be p o ec ed agains he ad e se e ec s o an explosion. • When he explosion sp eads om a la ge olume essel o a smalle olume essel, he e is a signi ican inc ease in he educed explosion p essu e, despi e he ins alled opening on bo h essels. In addi ion o he elease openings, o he elemen s mus be used o ensu e su icien explosion p o ec ion. Tab. 2 summa izes he esul s o he la ge-scale explosion es s, om which he di e ences in pmax, p ed and (dp/d ) alues occu ing in closed essels and essels wi h a en ing a ea and wi h piping connec ed o he essels can be easily seen. The ex lame eloci y is o he connec ed pipe. • Row 1 also summa izes he p ope ies om he labo a o y ins umen VA-20; when compa ed wi h la ge-scale explosion es s, i is possible o see di e ences in he alues o explosion pa ame e s. • The alues o pmax we e de e mined o he closed con aine s ( ows 1, 2, 7). • The alues o p ed we e de e mined o he essels wi h an ins alled en ing a ea ( ows 3, 8, 9). • In he case o connec ing he piping o he essel ( ows 4, 5, 10, 11) we e measu ed p ed on he essel i sel as well as on he connec ed piping. • In he case o bo h essels wi h en ing a ea and in e connec ed by pipes ( ows 6, 12), he p essu e on bo h essels was measu ed. In he i s case ( ow 6), he dus -ai mix u e was ini ia ed in N1 and sp ead h ough he pipes o N2. In he second case ( ow 12), he mix u e was ini ia ed in N2 and sp ead in he di ec ion o N1. The g aphical ep esen a ion o he ob ained explosion p essu es on he VA-20, N1 and N2 is exp essed in he ig. 2. Flame olume Du ing he la ge-scale explosion es s, we also made es ima es on he olume o he lame ha occu s du ing he explosion in he N1 and N2 essels. The lame olume was es ed on a essel N1 wi h he en ing a ea DN 250 and N2 wi h he en ing a ea DN 775 and a pipe DN 150 wi h a leng h o 6 m. The lame olume inc eases wi h inc easing he essel olume and he size o he en ing a ea. The lame olume is always g ea e in he case o lame ans e om essel o essel han in he essel i sel . The la ges lame olume was eco ded on essel N2, when ans e ed om essel N1 o N2. Tab. 3 The lame olume du ing explosion ansmission Type o de ice Flame olume [m3] N1 wi h pipe 8.77 Connec ed essels - ini ia ion in N1 185.63 N2 wi h pipe 130.99 Connec ed essels - ini ia ion in N215.10 pp. 8-14, DOI 10.35182/ ses-2020-0002 T ansac ions o he VSB - Technical Uni e si y o Os a a Sa e y Enginee ing Se ies, ISSN 1805-3238 Vol. XV, No. 1, 2020 14 Re e ences Ba knech , W. 2011. Dus explosions, Cou se, P e en ion, P o ec ion. Sp inge Be lin Heidelbe g. Ba lo á, I., Damec, J. 2002. P e en ion o echnological equipmen . 1s edi . Os a a: SPBI. (in Czech) ČSN EN 13821:2005. Po en ially explosi e a mosphe es. Explosion p e en ion and p o ec ion. De e mina ion o minimum igni ion ene gy o dus /ai mix u es. Damec, J. 2005. Explosion P e en ion. 1s edi . Os a a: SPBI. (in Czech) Eckho , Rol K. 2003. Dus Explosions in he P ocess Indus ies. Thi d Edi ion. Gul P o essional Publishing is an imp in o Else ie Science. Jankůj, V., Be na ík, A. 2018. In luencing o maximum explosi e pa ame e s o igni ion ene gies o dus -ai mix u es [online]. T ansac ions o he VSB - Technical Uni e si y o Os a a, Sa e y Enginee ing Se ies, 2018 [ci .2020-07-31]. A ailable a : h p:// ses. sb.cz/Home/A icleDe ail/359. Pang, L., Zhao, Y., Yang, K., Zhai, H., L , P., Sun, S. 2019. Law o a ia ion o low densi y polye hylene dus explosion wi h di e en ine gases [online]. Jou nal o Loss P e en ion in he P ocess Indus ies, 2019 [ci .2020-07-31]. A ailable a : h ps://www.sciencedi ec .com/science/a icle/abs/pii/S0950423018308878. O líko á, K., Š och, P. 1999. Chemis y o combus ion p ocesses. 1s edi . Os a a: SPBI. (in Czech) STN EN 60079-10-2 (33 2320):2015. Explosi e a mosphe es - Pa 10-2: Classi ica ion o a eas - Explosi e dus a mosphe es. STN EN 13237 (38 9612):2013. Po en ially explosi e a mosphe es.Te ms and de ini ions o equipmen and p o ec i e sys ems in ended o use in po en ially explosi e a mosphe es. STN EN 14034-1+A1 (38 9684):2011. De e mina ion o explosion cha ac e is ics o dus clouds.Pa 1:De e mina ion o he maximum explosion p essu e pmax o dus clouds. STN EN 14034-2+A1 (38 9684):2012. De e mina ion o explosion cha ac e is ics o dus clouds.Pa 2:De e mina ion o he maximum a e o explosion p essu e ise (dp/d )max o dus clouds. STN EN 14034-3 (38 9684):2012. De e mina ion o explosion cha ac e is ics o dus clouds.Pa 3:De e mina ion o he lowe explosion limi LEL o dus clouds. STN EN 14034-4+A1 (38 9684):2011. De e mina ion o explosion cha ac e is ics o dus clouds.Pa 4:De e mina ion o he limi ing oxygen concen a ion LOC o dus clouds. say ha he echnology is explosion-sa e. The e o e, he nex s ep, a e assessing he p ope ies o he dus , mus be o de e mine he concen a ion o dus inside he echnological equipmen and o assess he possibili y and e ec i eness o ini ia ion sou ces ha may lead o he ini ia ion o an explosi e a mosphe e. Acknowledgemen s This a icle was w i en in connec ion wi h esea ch p ojec suppo ed by wo ins i u ions, SLOVNAFT, a.s. and he Facul y o Sa e y Enginee ing VŠB in Os a a and i was implemen ed on he basis o a mu ual Se ice con ac numbe 4220003851 o De e mine EX pa ame e s o powde s. We ha e come o he conclusion ha PE dus gene a ed in he echnology o p oduc ion and s o age o PE g anules is e y explosi e in a mix u e wi h ai , i canno be unde es ima ed in e ms o c ea ing an explosi e a mosphe e and he isk o explosion. The isk o explosion occu s whe e e i canno be comple ely uled ou . The e o e, i is impo an o know he subs ances wi h hei p ope ies ha a e p esen in he echnology, he echnological p ocesses ha ake place in he echnology and he ope a ing condi ions unde which he p ocess akes place. These indings a e impo an ac o s o pe o ming a de ailed analysis. I he concen a ion o he mix u e inside he echnological equipmen is below he alue o he dange ous concen a ion and a he same ime he e is no se ling and s icking o dus , hen we can pp. 8-14, DOI 10.35182/ ses-2020-0002