Engineering Abstracts 1950

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Engineering Abstracts from 1950

Explosion of Empty Diesel-oil Fuel Tank

The vapours of petrol, when mixed with the proper proportion of air, are highly explosive, a fact which is known to most men whose work requires them to handle this fuel. In some quarters, however, there seems to be an impression that the vapours of Diesel oil are not dangerous. This is a fallacy which , in one recen t casu a lty , cau sed th e d eath o f a w o rk m a n

w h o w a s atte m p tin g to w eld a leak in a Diesel-oil tank . As regards the explosiv equalities of Diesel-oil vapours, these are of approximately the same order as those o f p etrol. T h e reason

th at D iesel o il is safer to h an d le th a n p etro l is th a t it is n o t as vo latile. C o n se q u e n tly th e liq u id does n o t evap o rate ai read ily, an d , th erefo re, at a n y g iv e n tem p eratu re, p e tro l w ill

evo lve a greater q u a n tity o f fu m es th a n D iese l oil. W h e n , h ow ever, d u e to heat o r o th er circu m stan ces, D iese l o il has evap o rated , its v ap o u rs are as d an gero u s as th o se o f p etro l an d

h ave o n ly to be m ix ed w ith th e co rre ct p ro p o rtio n o f air to fo rm a co m b in atio n m erely a w a itin g a sou rce o f ig n itio n to exp lod e. In th e case referred to , an u n in sp ected fish in g vessel,

p ow ered w ith D iese l m o to rs, d evelop ed a leak in on e o f its fu el tan ks. A w eld er w a s sen t fo r to rep air th e leak. A s p rep ara tio n fo r h is o p eratio n s, th e tan k w as em p tied o f all fu el,

b u t n o atte m p t w as m ad e to g as-free it. T h e w eld er, w h o w as eq u ip p ed w ith a p etro l to rc h fo r w e ld in g th e tan k , seated h im self o n a sto ol at th e en d o f th e ta n k an d p rep ared to w eld th e

d efective seam . S h o rtly after th e w o rk w a s b eg u n an ex p lo sio n o ccu rred w h ic h k n o ck ed a n earb y crew m em b er d o w n w ith o u t

in ju rin g h im to a n y exten t an d th re w th e w eld er ag a in st a co lu m n in th e vessel, fra c tu rin g h is sk u ll A fire en su red an d d u e to th e h eat, gas, an d sm oke, th e co m p artm e n t co n ta in in g

th e tan k s co u ld n o t be en tered u n til th e a rriva l o f th e to w n fire d ep artm en t ap p ro x im a tely 10 o r 15 m in u te s later, at w h ic h tim e firem en w ith gas m asks ex tricate d th e w eld er fro m th e

tan k ro o m , p la ced h im in an am b u lan ce, a n d ru sh ed h im to th e lo cal h o sp ital w h ere he d ied a p p ro x im a te ly 10 h o u rs later. The lesson from this ca su a lty is o b v io u s— n o ta n k w h ich has co n ta in ed o il fu el, even B u n k e r C , sh o u ld be w o rk e d o n w ith a w e ld in g to rch u n til it has been gas-freed .

— Marine Engineering and Shipping Review, Vol. 55, September 1950, p. 80.

Diesel Engine Research

T h is p ap er review s D iesel en g in e research carried o u t at the Diesel Research Laboratory of Caterpillar Tractor Co. under the sponsorship of the author as Director of Research. For many years intensive effort has been made to understand the combustion process in this type of engine by a better knowled g e o f th e fu n d a m en ta ls o f ig n itio n a n d th e m ech an ism o f

th e co m b u stio n p rocess, an d th is stu d y has been d evelop ed

in th e la b o ra to ry o n a co m p etitive basis. O rig in a lly six co m b

u stio n system s w ere p u t to trial an d a m o d ified p reco m b u stio n -

ch am b er en g in e w o n th e p alm o f v ic to ry o n th e basis o f its

a b ility to m ain tain u n ifo rm ity over exten d ed p erio d s o f op eratio

n . B rie fly , th e ch ara cter o f th e co m p ara tiv e co m b u stio n

stu d ies fo llo w e d tw o gen eral cla ssifica tio n s: (1) visu al co m b u stio

n stu d ies; (2) stu d y o f co m b u stio n -ch a m b er d ep osits. In

o rd er to m ake exten d ed stu d ies o f th e co m b u stio n p h en om en a

b y visu al m ean s, a q u a rtz w in d o w w as d esign ed to ach ieve

m ax im u m clean lin ess w ith o u t th e d istractio n o f soot co n d e n satio

n o n th e co ld w in d o w s. T h e a u th o r d escribes th e p reco m b

u stio n -ch am b er p rocess, an d deals w ith th e co m p o sitio n o f

co m b u stio n gases, flam e d u ra tio n , tem p eratu re d istrib u tio n , th e

m ech an ism o f ig n itio n , an d co m b u stio n -ch a m b er dep osits. H e

also d iscu sses th e d evelo p m en t o f fu e l-in je ctio n eq u ip m en t, p retim

in g , p recalib ratin g , an d th e ev o lu tio n o f th e fu el p u m p ; he describes th e ch aracteristics o f several typ es o f ch eck v alve an d

fu el valve, an d th e fu e l-p u m p co n tro l o f en g in e torq u e

ch aracteristics. S p ra y ch aracteristics an d th e flo w th ro u g h the

fu el-va lv e orifice are also exam in ed . C o m m en ts are m ad e u p o n

m aterials fo r cy lin d e r lin ers an d p isto n rin g s, an d th e effect

o f fu el in clu sio n s o n cy lin d e r w ear; lu b ricatio n is also c o n sidered

. It is b elieved th at excellen t p erfo rm a n ce has been

ach ieved in th e p reco m b u stio n -ch a m b er en gin e w ith a m in im u m

o f co m p licatio n in th e fu e l-in je ctio n eq u ip m en t, an d th at th e d evelopment of this principle o f co m b u stio n h as n o t yet reached its limit of progress.

— James Clayton Lecture by C. G. A. Rosen, read at a meeting of The Institution of Mechanical Engineers, 14th November 1950.