Mines and Bunkers Volume 10, Fire Safety Aspects of Polymeric Materials (1980) / Chapter Skim
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DESIGN CRITERIA IN MINE SAFETY AND HAZARD CONTROL
DESIGN CRITERIA IN MINE SAFETY AND HAZARD CONTROL
Pages 88-120
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From page 88... ...
5. 2 Approaches to Design Criteria Development The trad itional approach to mine safety and hazard control has been frag 88
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From page 89... ...
Fuels - gases and dust ; structu ral l u m ber or other materi als ; com busti ble com ponents of production equ ipment, conveyor systems, transportation equi pment, condu its, electrical distr i bu tion systems, and venti l ation systems ( i ncluding insulation materials, hydrau l i c h oses and flu id, conveyor belts, venti l ation cloth, etc.
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From page 90... ...
The complete appl ication of the systems approach in developing design criteri a that provide for mine safety and hazard contro l requi res a greater understanding of fire dyna mics and rel ated processes than is possi ble today. For example, the sea· worthi ness of a damaged ship can be ascertai ned quickly, and the effect of correc· tive actions (e.g., flooding selected compartments)
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From page 91... ...
Particul arly needed are i mproved flammabi l i ty and flame spread tests, an evaluation of the toxicity of belt com bustion products, and im proved fire detection and su ppression systems.
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From page 92... ...
Fol l owing th is disaster, the Nationa l Coal Board di rected a l l belt manufacturers in G reat Britai n to proceed i mmediately with the development and production of a fi re-resistant belt. The National Coal Boa rd also establ ished specifications for the acceptance of fi re-res istant conveyor belting, and these included a mandatory drum friction test.
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From page 93... ...
5. 3.4 Fire Tests The Federal Schedule 28 test designated to determ i ne the fi re resistance of coal mine conveyor belts is considered of questionable rel iabi l ity.
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From page 94... ...
The abi l i ty to sustain fl ame propagation and the effects of preheati ng, belt width, and coal dust grease accu m u lations a lso h ave been evaluated. F u l l -scale fi re tests have confi rmed some of the l aboratory-scal e resu lts and trends, and the inadequacy of the existing fi re retardancy acceptance test h as been demonstrated fu rther.
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From page 95... ...
5.3.6 Suppression of Conveyor Belt Fires Ex isti n g regu l ations requ ire that automatic fi re exti nguish ing systems (spri n kler or deluge ty pe) be installed at coal mine belt conveyor drives in accordance with specified belt areas and water flow rates an d suppl ies.
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From page 96... ...
is aimed at establish i ng criteria for test methods ; developing standard tests for flamm abi l ity, smoke emiss ion, toxicity, and integrity ; and applying these tests to wire and cable insulating materials presently in use and to the newer polymeric materi als being proposed. Althou gh this study is be i ng conducted pri mari l y for th e rapid transit i ndustry, i ts resu lts should prov i de val uable data to the mining indus try, as wel l as all others, si n ce ra pid transit tu nnel and mine requ i rements for electrical power and large equ ipment in confined spaces are very si m i l ar.
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From page 97... ...
Polyol efi n /pol yolefin jacket Si l i cone ru bber/s i l i cone ru bber jacket Teflon®/Tefl on® jacket Tefzei®/Tefzel® jacket Tefzei®/Shield/Tefzel® jacket The flammabil ity tests i n dicated that : 1 . The selected test method is capable of providi ng repeatable test resu lts.
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From page 98... ...
2. I t wil l be possi ble to use the test resu lts to categori ze and ran k insu l ation materials and constructions with respect to thei r abil i ty to provide a fire safe env i ron ment in terms of circu it integrity.
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From page 99... ...
In many mine fi res, a malfu ncti on ing el ectrica l ignition sou rce ignited the hydraulic hose and hydrau lic fl uid di rectl y or through the bu rning electri c insu l ation. The hydra u l ic system then ignited a secondary or te rtiary fuel, often with the aid of ex ternal l y accu mulated coal dust and grease, and a large-scale fire resulted.
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From page 100... ...
. In 1 975, a research program concerned with improved fire safety of coal mine hydrau l ic systems was initiated ( Ladov and Law 1 978)
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From page 101... ...
The foam, however, is fl ammable and su bject to spontaneous combustion, and its decom posi ti on products represent a signifi cant tox ic hazard. Past developments in foam tech nology were concerned with appl ication tech nique, testi ng, flammabi l i ty, flame propagation research, and the use of flame 1 01
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From page 102... ...
3. The poss i bi l ity of spontaneous ign ition exists ( bu t only with in four h ou rs afte r appl ication and only i f i m prope rly appl ied )
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From page 103... ...
They descri bed the foam formu lations, appl ication techn i ques, and physical proper· ties of the foam as wel l as the fire and potentia l toxicity hazards ; presented resu lts of l arge-scale s i m u l ated coa l mine fi re tests and vari ous l aboratory flame spread and therma l deformation tests; and proposed a fl ame penetration test as an acceptance requi re ment. A l ater report by these same researchers ( M itche l l et al.
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From page 104... ...
These problems, however, are not considered to sign i f i cantly alter the test resu lts and it may be that experience wi l l i mprove the appl ica tion tech nol ogy, Assuming that such improvements wi l l be m ade, the report in di cates th at at l east two (and possibly fou r) acceptable and econ om ical protective 1 04
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From page 105... ...
I n t h e experi ment, fla me did not spread o n t h e su rface of the foam upon appl ication of an i ntense ign ition sou rce, and it was concl uded that the material does not present a fi re hazard even without a protective coati ng. Other efforts to mod ify or replace traditional polyurethane foam a lso have been undertaken, Cal l ery Chemica l , under a contract to the U.S.
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From page 106... ...
The only cu rrent coal m ine requ i rements for automatic fire sen s ors rel ate to their use with underground conveyor belt haulageway protection. The regu l ations are written in terms of thermal poi nt type sensors (or com bustion product sensors if they offer equivalent protecti on)
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From page 107... ...
5.7. 2.3 Spontaneous Combustion Research The main factors that contribute to spontaneou s com bustion in coal mines are : ( 1 )
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From page 108... ...
The incidence of fricti onal spark ign ition at the mine face has i ncreased signifi· cantly wi th the advent of the continuous mining machine. The m ajor h azard of a face i gnition lies in the possi bi l ity that it may i n i tiate an extensive coal dust ex plosion.
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From page 109... ...
Such disaste rs usual l y fo l l ow accidental ign ition of a methane poc ket or roof l ayer, wh ich may develo p sufficient violence to pick up, disperse, and ignite coal dust lying on nea rby mine surfaces. A sel f-generati ng dust explosion then can develop and propagate for great distances in the m ine.
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From page 110... ...
5.8.3 Remote Sealing System for Exti nguishing Coal Mine F ires ( King 1 978) Uncontro l led coal mine fires are of great concern to the m i n i ng i ndustry becau se they can not be d i rectl y exti ngu ished and may requ i re th at the enti re mine be sealed.
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From page 111... ...
a froth foam topping syste m for com pleting each seal, (4) a com bustion ty pe inert gas generator for convey ing the fly ash and inerti ng the sea led area, and ( 5)
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From page 112... ...
Over the past 1 5 years, several attem pts have been made to app l y the remote seal ing concept in underground fi res in active coal mines, but most of these efforts have achi eved on l y l i mi ted or no success becau se of inadequate seal ant m ateria l s, seri ous equipment l i m itations, or i nsurmountabl e mine wate r problems. A parti a l l y successful effort occu rred a few yea rs a go when a prototype o f the present re mote seal ing system was used to iso l ate and extingu ish an underground fire at the Eastern Associated Coal Corporation 's Jaonne mine i n R achel , West V i rgin ia.
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From page 113... ...
A contract to eval u ate the non-coal mine shaft fi re and smoke hazard problem and to develop an d demonstrate a rel i a bl e mine shaft fire and smoke control system was awarded in 1 974. This system was to be flexi ble in design so that with modifications it wou l d be appl icable to the majori ty of metal and non-metal mine shafts and adjoi ning sh aft stations.
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From page 114... ...
The contract was extended for an additional 1 5 months to perm it i nsta l l ation of the prototype system i n at least two operating m i ne shafts, l on g-te rm re l i abil ity testi ng, and conduct of cost-effectiveness eva l u ations of optional system designs and uses. I t appears that the fi rst-generation mine shaft fi re and smoke protection system has a fast response to fi re situ ations and that the presence of spri n klers i n the shaft a nd shaft station area is much more effective in extingu ish i ng fi res than the com mon ly used shaft-col l ar water ri ngs.
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From page 115... ...
Another objective of the fi rst work was to find the most fireprone class of equi pment and to solve its fi re problem using a system flexi ble enough to be appl ied to other l arge m obi le mine equ i pment. This hazard analysis stu dy resu lted in deve l opment of "dual sen si ng, automatic with manu al overri de, fi re detection and su ppression system" for rear dump haulage trucks with a capacity of over 1 00 tons.
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From page 116... ...
S B u reau of M i nes entered into a cooperative agreement with the Ansul Company, Marinette, Wisconsin, to hel p in the eva l u ation of a new, pneu matica l l y operated, low-cost, automatic fire protection system.
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From page 117... ...
Recommendation: Al l basic information and techni ques needed to apply the overa l l systems approach in mine safety and h azard control shou l d be developed, Conclusion: Bel t conveyor systems sti l l represent a major fire hazard in m ines ; acceptance test methods seem inadequate a n d large-scale fire testing is i ncom plete. Recommendation: Test methods that provide a mean i ngfu l and quantitative rati ng of the fl a mmabi l i ty, fl ame spread, and toxicity of com bustion products of belti ng materi als shoul d be developed.
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From page 118... ...
The demonstration and refinement of coal dust explosion barriers shou l d be continued, and their opti mum l ocation in relati on to face areas sh ou l d be identified The remote seal i n g technology recentl y developed for the control of coal mine fi res shou l d be perfected. The ongoi ng mine shaft fire and smoke protection system development progra m shou ld be ampl i fied ; this system shou l d be i nsta l l ed in metal and non-metal mines.
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From page 119... ...
R Fo rshey , Coal Mine Combustion Products: Conveyor Belts, U .S.
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From page 120... ...
M Tay lor, "Wire and Cable I nsu lation for Rapid Transit Systems," paper presented to American Chemical Society , Division of I n dustrial and Engineeri ng Chemistry National Symposium on Fire Safety Aspects of Polymeri c Materials, June 1 977 .
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