Journal of the Institute of Petroleum, Vol. 26, No. 200

P.

J O U R N A L OF

T H E I N S T I T U T E O F P E T R O L E U M

FOUNDED 1913 INCORPORATED 1914

Vol. 26 J U N E 1940 No. 200

C O N T E N T S

PACK

Analysis and T esting of L ubricating Greases. By

M . W. W ebber . . . . . .

Octane Ratings o f Pure H ydrocarbons. By J. Sm itten- berg, H :.H oog, B. H . Moerbeek, and M . J. v. d.

Z i j d e n ...

Tw enty-Sixth A nnual R eport . . . . .

Annual G eneral M eeting . . . .

Benevolent F und . . . . . . .

Abstracts . . . . . . . .

Book Review . . . . . . .

Book Received . . . . . . .

Institute Notes . . . . . . . i-iii

Published by The Institute oí Petroleum.

A ddress: c/o The University of Birmingham, Bdgbsston, B irm in g h am , 15.

Printed in Great Britain by Richard Clay and Company, Ltd., Bungay, Suffolk.

All rights t f Publication or Translation are Reserved.

THE INSTITUTE OF PETROLEUM

C O U N C IL , 1 9 3 9 - 4 0

P R E S ID E N T : Prof. A . W . N a s h , M .S c .

A lfre d C . A d a m s Lt.-C o l. S . J. M . A u ld ,

O .B.E., M .C ., D .Sc.

Prof. J. S. S. Bram e, C.B .E., F.I.C.

T he Rt. H o n. Lord C a d m a n , C .C .M .C ., D .S c., F.R.S. .

P A S T -P R E S ID E N T S :

T. D ew hu rst, A .R .C .S , A . E. D unsfan, D .S c., F.I.C.

S ir Th om as H. H o lla n d , K .C .S .I., K .C .I.E ., D .S c., F.R.S.

J. K e w le y , M .A ., F.I.C.

V IC E -P R E S ID E N T S ■ A s h le y C a r ie r , A .M .I.M e ch .E .

C . D a ile y , M .I.E.E.

F. H. C a r n e r , Ph.D ., M .S c ., F.I.C.

M EM BER S O F C O U N C I L :

J. M c C o n n e ll S a n d e rs, F.I.C.

F. B. T h o le , D .S c., F.I.C.

C . H. C o x o n

A . Frank D a b e ll, M .I.M ech.E.

E. A . E vans, M .I.A .E .

E. B. E van s, P h.D ., M .S c ., F.I.C.

W . E. C o o d a y , A .R .S .M ., D .I.C . A . C . H a rtle y , O .B .E ., F .C .C .I.

Prof. V . C . Illing, M .A . J. S. Ja ck so n , B .Sc., F.I.C.

J. A . O r ie l, M .C ., M .A . E. R. R e d g ro v e , Ph.D ., B.Sc.

C . A . P. So u th w e ll, M .C ., B.Sc.

H. C . Tett, B .Sc., D .I.C . A . B e e b y Th om p so n , O .B.E.

A . W a d e , D .Sc., A .R .C .S . W . J. W ils o n , F .I.C ., A .C .C .l.

C . W . W o o d , F.I.C.

A rth u r W . E astlake, A .M .I.M e ch .E ., H o n o ra ry S e cre ta ry

H O N O R A R Y E D IT O R : Dr. A . E. Dunstan H O N O R A R Y A S S O C I A T E E D IT O R : Dr. F. H . C a r n e r H O N O R A R Y T R E A S U R E R : T h e Rt. H on. Lord P le n d er, C.B .E.

S E C R E T A R Y : S. J. A s tb u ry , M .A .

F ) Vo l.

20. N o. 200. J u n e 1040.

T H E A N A L Y S I S A N D T E S T I N G O F L U B R I C A T I N G

G R E A S E S . *

B y M. W . W

.

A s th is p a p er is based on w ork carried o u t in th e lab o rato ry of a w orks which is solely engaged in th e m anufacture o f lubricating grease a n d allied products, th ere is no reference to service conditions. I ts scope is confined solely to soap greases.

Tbe appearance o f th e grease is th e first item in its exam ination. P rom th is i t is possible to learn w hether i t is well m ade, sm ooth a n d o f uniform te x tu re , free from aggregates o f soap, sep arated oil, w h eth er it is m ade from lime or soda soap, an d if of fibrous stru ctu re. The chem ist has m uch to learn from th is prelim inary observation. A tra in e d observer can tell a t a glance m uch of w h a t he will subsequently prove b y a detailed lab o ra­

to ry exam ination. I t is therefore im p o rta n t th a t th e eye should be train ed in observation. T hen th e nose should be fam iliarized w ith th e odours em an atin g from greases. Much w ork can be elim inated if fa ts can be detected by smell. A cup-grease m ade from f a tty acids has a different smell from one m ade from n e u tral fats, an d m ost hig h -tem p eratu re soda greases possess characteristic odours.

So a p Ba s e a n d Co n t e n t.

A t least 90 per cent, o f th e greases on th e m a rk e t contain eith er lim e or soda soaps. As a rule, these are readily distinguished by dropping a little on to boiling w ater. Soda-soap greases im m ediately render th e w ater m ilky, due to soap dissolving in th e w ater a n d em ulsifieation o f oil, whereas lime-soap greases are unaffected by th e w ater. W hen th e tw o soaps are present in th e sam e grease th e te s t only gives indication o f soda soap.

Greases m ade from lead soaps frequently sink, due to th e ir high specific g rav ity , b u t th is depends on th e percentage o f lead a n d an y aeration.

Alum inium -soap greases are usually d etected b y th e ir tran sp aren cy and th e ir elasticity when heated. O ther soaps, such as zinc, barium , m agnesium , an d potassium , are encountered on rare occasions, a n d m u st be sought in th e ash a fte r incineration.

T he soap content is usually determ ined by decom posing th e grease w ith d ilute hydrochloric acid, ex trac tin g w ith petroleum other, and th e n t i t r a t ­ ing th e w ashed e th er solution, w hich contains b o th th e f a tty acids from soap a n d an y free f a tty acid originally present. A fter due a d ju stm e n t for th e la tte r, th e soap content is calculated, using a n acid value of

. I f g reater accuracy is desired, th e f a tty acids can be sep arated and weighed, an d th e ex act acid value determ ined.

The operations sound sim ple and straig h tfo rw ard , b u t difficulties in m anipulation are often experienced. A sim ple alte rn a tiv e m ethod is to e x tra c t th e grease w ith acetone in a Soxhlet. E xperience w ith greases of know n com position has shown th a t a n accuracy of

p er cent, is readily

* P re se n ted to a M eeting o f th e L u b ric a tio n G ro u p of th e I n s t i tu t e a t T h e R o y a l S o ciety of A rts , L o n d o n , W .C . 2, on T h u rs d a y , 2 2 n d F e b ru a ry , 1940.

U

2 7 4 W E B B E R : T H E A N A LY SIS AND

obtained. T h is m eth o d is p a rtic u la rly useful in th e case of lime-soap grease m ade w ith wool-grease stearines, as th e unsaponifiable p o rtio n is com pletely soluble in h o t acetone. W hen using th e norm al m ethod, which is described above, i t is im possible to o b tain sharp separations. I t is preferable to d eh y d rate th e grease by drying in a n oven before ex tractio n in th e Soxhlet, a n d base calculations on th e original wreight of th e grease.

A bout 5 gram s o f a lim e-soap grease can be ex tra c te d satisfactorily w ith 60/70 mis. of acetone in

hour. Soda-soap greases m ay require e x tractio n for a t least 3 -4 hours, p a rticu larly those of high soap content and p ro ­ nounced fibrous stru c tu re . W ith th is m ethod th ere is a g re a t saving of tim e a n d trouble in m ost cases, and it is equal in accuracy to th e norm al m ethod. I t m ay bo th a t ex tra c tio n can be speeded up b y th e use o f a solvent o f ra th e r higher boiling point.

Should fillers be present, th e contents o f th e th im b le should be ex trac ted again w ith alcohol in th e case o f soda-soap greases, an d toluene in th e case o f lim e-soap greases. The fillers can th e n be exam ined an d w eighed, an d th e necessary a d ju stm e n t m ade.

The general adoption o f a sta n d a rd ex tractio n m ethod for th e d eterm in a­

tio n o f soap co n ten t o f lubricating greases would probably avoid difficulties som etim es experienced w hen th e lab o rato ry o f th e user is m ore accustom ed to analysing quite different products.

F rom th e user’s p oint o f view d eterm in atio n o f th e soap co n ten t is becoming less im p o rtan t, as is shown by th e p resen t tendency to om it s tric t details of th e com position w hen form ulating specifications.

Mi n e r a l Oi l Co n t e n t.

The m ineral oil is determ ined b y decom posing th e grease w ith dilute hydrochloric acid and ex tra ctin g w ith petroleum ether, separating th e eth er solution, saponifying th e f a tty acids a n d a n y fa t present, an d d e te r­

m ining th e unsaponifiable oil in th e norm al m anner. T he m ineral oil will, of course, be contam inated w ith any unsaponifiable m a tte r from th e fats used in th e grease, b u t th is usually does n o t affect appreciably th e exam ina­

tio n o f th e m ineral oil for colour, viscosity, g ra v ity , flash p oint, a n d pour point.

N atu rally , only a sm all q u a n tity o f oil can conveniently be ex tracted . Viscosity a t 140° F . is usually determ ined in a sm all U -tube viscom eter.

T he specific g ra v ity is found b y ad ju stin g a m ix tu re of alcohol an d w ater so th a t a drop o f th e oil ju s t rem ains in suspension, an d th e n ta k in g th e g ra v ity o f th e m ixture. A n ap p ro x im ate estim atio n o f th e open flash po in t can be m ade b y carefully h eatin g a little of th e oil in a crucible on a sand-bath. T he pour p o in t can be determ ined b y cooling th e oil in a te st- tu b e , b u t th e Air M inistry a p p a ra tu s can be used if sufficient oil is available.

A n alte rn a tiv e m ethod for th e d eterm in atio n o f th e m ineral oil content is b y evaporation o f th e acetone e x tra c t resulting from decom position of th e grease w ith acetone in a Soxhlet. T he residue is weighed and reported as m ineral oil. T he oil is c o n tam in ate d w ith free f a tty acid, n e u tral fat, a n d unsaponifiables, b u t th e to ta l o f these is usually less th a n

p er cent.

I f a n accu rate analysis is needed, separate determ in atio n s will be m ade of

th e free acid and free fat, a n d due allowance m ade. A separate estim atio n

TESTIN G OF I/UBKICATING GREASES. 2 7 5

o f th e unsaponifiables from th e fats is extrem ely difficult, an d no m ethod is suggested. The contam inated m ineral oil can be used for th e physical te sts, as th e contam ination will n o t cause errors any g reate r th a n those duo to th e m ethod o f te s t of sm all q u an tities o f oil.

Fr e e Ac i d a n d Al k a l i.

T he m ethods described in I.P .T . Serial D esignation L.G.5 are reliable an d satisfactory for routine estim ation of free acid or alkali. H ow ever, in th e case of soda-soap greases, containing appreciable am ounts o f free fa t as well as free alkali, it is preferable n o t to boil th e solution, as a n y error due to th e presence of carbon dioxide will alw ays be less th a n th a t caused by saponification of n eu tral fa t on boiling. T he determ ination o f free acid in alum inium -soap greases can be effected b y ex tractio n w ith cold n eu tral alcohol an d th e n titra tin g . A suitable procedure is to weigh 10-15 gram s into a conical flask, shake thoroughly for 5 m inutes w ith 50 mis, alcohol, allow to settle, an d decant th e alcoholic e x tra ct. T his should be repeated, th e ex tra c ts u n ited an d titra te d in th e norm al m anner.

W hile free alkali in soda- or lime-base greases m ay have little effect on bearing m etals, th e presence o f a large proportion is definitely undesirable, as it affects adversely sta b ility a t elevated working tem peratures. I f the grease is to be used w ith alloys containing alum inium or m agnesium , no free alkali should be allowed.

The determ ination o f free f a tty acid (m ineral acid is, of course, never to be found in a com pound lubricating grease) is m ost necessary, as th e presence of an y considerable am ount is th e principal cause of corrosion of bearing m etals. A reasonable lim it is a n acid value of 0-2 m g. K O H per 1 gram of grease— i.e., approxim ately 1 p er cent, f.f.a. as oleic acid. A grease com plying w ith th is will norm ally be satisfacto ry from th e p oint of view o f corrosion, w hilst th e free f a tty acid can be sufficient to ensure sta b ility w hen heated.

Specifications have been issued w hich specify th e p H value for th e d e te r­

m ination of freedom from a c id ity or alkalinity, b u t th is would ap p ear to be o f lim ited value w ith lubricating greases, as appreciable q u an tities o f freo f a tty acid m ake little or no difference to th e ap p a ren t p H value.

Wa t e r Co n t e n t.

T he w ater content is m ost accurately determ ined by distillation using th e D ean a n d S ta rk m ethod as described in I.P .T . Serial D esignation E.O. 14. I t is n o t satisfacto ry to determ ine th e w ate r b y heating in an oven, as th is does n o t ensure th e rem oval of all w ater from th e grease. In addition, th ere m ay be some loss o f volatile con stitu en ts o f th e m ineral oil.

These tw o errors seldom ex actly counterbalance one an other. The to ta l loss o f volatile m a tte r m ay in some cases be considered to be o f im portance to d etect th e use o f inferior oils.

I n lime-soap greases th e presence of a certain am o u n t of w ater is essential

for th e ir stab ility , b u t an excess is to be avoided. Some specifications call

for a lim it o f

per cent, for w ater w ith o u t due concern ab o u t th e soap

content. I n general th e optim um p roportion o f w ater is

p er cent, o f th e

soap content. Such a lim it would allow th e presence o f sufficient w ater for

2 7 6 "WEBBER : T H E A N A LY SIS AND

th e m an u factu re of a stable grease, w hilst th ere would n o t be an excess to cause corrosion.

I n th e case o f sodium or alum inium base greases th e w a te r co n ten t m ay be reduced to negligible proportions, although in th e case o f greases con­

ta in in g large am ounts o f soda soap a q u a n tity up to 0-5 p e r cent, o f w a te r m ay be retain ed , and th is will p ersist how ever high th e tem p era tu re of d eh y d ratio n during m anufacture.

Un s a p o n i e i e d Fa t.

T he co n ten t o f unsaponified fa t can be d eterm ined eith er from th e petroleum eth er e x tra c t a fter decom position w ith hydrochloric acid and ex tractin g w ith ether, or from th e acetone e x tra c t resulting from th e soap d eterm ination using th e S oxhlet a p p a ra tu s as described earlier in th e paper. I n b o th cases th e free f a tty acids in th e solution are neutralized, followed b y an estim ation o f th e saponification value. The percentage o f n eu tral fa t can th e n be calculated w ith sufficient accuracy if th e saponifica­

tio n value of th e fa t is ta k e n as 195.

U ntil recently it w as th o u g h t th a t th e deliberate inclusion o f unsaponified fa t in a grease im proved bo th sta b ility a n d lubricating efficiency. I t is now generally agreed th a t th e presence of free fa t is to be avoided. I ts decom position leads to th e form ation o f undesirable products. Greases stable to h e a t can be m ade w ith o u t excess n eu tral fa t. T ests on th e T im ken m achine hav e show n th a t th e presence of free fa t does n o t ap p re­

ciably reduce friction or increase load capacity.

As h Co n t e n t.

T he im portance of th e determ in atio n o f ash left on ignition b y a lu b ric a t­

ing grease is often denied. I t does, however, serve useful purposes. Glazed porcelain crucibles are q u ite satisfacto ry for th e ignition. T he grease should be slowly a n d stea d ily b u rn t off a t as low a tem p eratu re as possible.

T he crucible is th e n h eated to redness u n til all carbonaceous m a tte r has d isappeared an d ig n ited to con stan t w eight.

The ash can th e n be exam ined q u alitativ ely o r q u a n tita tiv e ly by th e usual m ethods for th e d eterm in atio n o f base a n d m ineral fillers. In th e case o f pu re greases th e determ in atio n of ash will give a very good idea of th e am ount o f soap present. The ash co n ten t can be used as a ra p id ro u tin e check on successive deliveries o f th e sam e g rad e o f grease.

W here m ixed-base greases are u n d er exam ination, analysis of th e ash is a m a tte r o f im portance, as i t is o ften th e only practicable m eans o f d e te r­

m ining th e ty p e s a n d proportions o f soaps present.

Im p u r i t i e s.

B y im purities, as d istin ct from fillers, are m eant such foreign m a tte rs as g rit, d irt, particles o f wood o r m etal from containers an d p la n t. The presence o f im purities is usually due to careless handling during packing, as m ost greases are carefully filtered during m anufacture. Such a d v e n titi­

ous m a tte r can be determ ined visually by ex am in atio n o f th e grease in a

th in film on a sheet o f glass, o r on a n opaque w hite surface. S oft lime-soap

T ESTIN G OF LU B RICA TIN G G REA SES. 2 7 7

greases can also be exam ined b y passing th em th ro u g h a piece o f fine muslin, an d stiffer greases b y forcing th ro u g h finely woven wire cloth. A lter­

natively, th e grease can be dissolved in toluene, an d passed th ro u g h a filter- paper, or th is can be done m ore rap id ly b y e x tra ctio n in a Soxhlet.

Fi l l e r s.

The expression “ fillers ” is usually reserved for “ loading ” m aterial, such as gypsum or b ary tes, b u t th e te rm is often ta k e n to include such ingredients as g raphite, m ica, asbestos fibre, wool yarn , g ran u lated cork, all o f which are deliberately incorporated to increase th e efficiency of th e grease for p a rtic u la r applications. M ineral fillers can easily be determ ined from th e ash, w hilst com bustible fillers can be sep arated by filtratio n afte r decom position o f th e grease w ith hydrochloric acid an d petroleum other.

I f e x tractio n in a S oxhlet w ith acetone has been em ployed for th e estim a ­ tio n o f soap, th e fillers can be exam ined an d w eighed a fte r elim ination of th e soap by fu rth er ex tractio n of th e residue in th e thim ble w ith toluene.

I f a sep arate d eterm ination of soap is n o t m ade, th e original grease is e x tra c te d w ith toluene.

Ad d i t i o n Ag e n t s.

As in th e case of lubricating oils to-day, a num ber o f m aterials are being added in sm all or large proportions to lubricating greases to im prove th eir efficiency for various purposes.

C hlorinated w axes and sulphurized oils (with or w ith o u t th e presence o f lead soap) are add ed to increase th e load cap acity o f greases destined for rolling-mills, an d stam ping an d draw ing operations. The proportion o f sulphur or chlorine can be determ ined by fusing th e d eh y d rated grease w ith a m ix tu re o f sodium carbonate an d potassium n itra te or sodium peroxide.

The re su ltan t m ass is dissolved in w a ter a n d th e sulphates or chlorides are estim ated.

I n order to increase th e adhesiveness or stringiness o f greases, such m aterials as ru b b er latex an d highly polym erized pro d u cts are incorporated in th e grease. T he p roportion is usually less th a n 0-25 p er cent., and as determ in atio n b y analysis is extrem ely difficult, no m ethod is suggested.

S olid a d d itio n a g e n ts , su c h a s g ra p h ite , m ic a, a s b e sto s fibre, a n d w ool y a rn , a re d e te rm in e d a s fillers u sin g th e m e th o d s d esc rib e d e a rlie r in th e p a p e r.

I n th e case of colloidal g rap h ite th e p ro p o rtio n present is usually from 0-05 to 0-2 p er cent, and d eterm in atio n b y q u a n tita tiv e m ethods is beset w ith difficulties. I have found th a t th e best m ethod is to dissolve th e grease in toluene and to com pare d ilute solutions w ith know n stan d ard s.

Co r r o s i o n.

A ny corrosion caused b y a grease is usually due to excessive contents of free f a tty acid a n d /o r w ater, an d in some cases to th e presence o f chlorides or sulphates. A su itab le m ethod o f te s t is to ta k e pieces o f polished copper an d steel, a b o u t

inch square, cover th em p a rtly w ith th e grease, a n d allow to sta n d u nder in v erted w atch-glasses for a period o f a t le ast 24 hours.

A fter cleaning, th e test-pieces should show no discoloration o r p ittin g .

2 7 8 W E B B E R : T H E ANALYSIS AND

The te s t can be carried o u t a t room tem p eratu re, or higher if considered advisable.

Me l t i n g Po i n t.

M any sim ple m ethods hav e been suggested for th e estim ation o f th e m elting p oint, b u t i t is obviously desirable to have a sta n d a rd m ethod.

T he U bbelohde ap p a ra tu s w as originally designed for th e m elting p o in t of p etro latu m s, b u t during recent years i t has been applied to greases in general. To o b tain consistent results w ith soap-greases it is essential th a t a ir bubbles should n o t be included w ith th e grease w hen filling th e cup.

A pertures in th e m etal holder m u st be k e p t clear, a n d th e ra te of h eatin g accurately controlled. Discrepancies in th e results obtained w ith th e U bbelohde ap p a ra tu s in different laboratories are principally due to lack o f stan d ard izatio n o f th e cups, especially as regards th e orifice. S ta n d ­ ard izatio n of th e m ethod has recently been u n d e rtak e n b y th e B ritish S tandards In stitu tio n , an d no d oubt i t is a su b ject w hich will be considered fu rth er b y th e In s titu te o f P etroleum a t a n early date.

T he obtaining of consistent results w ith high-m elting-point soda-grcases of fibrous an d block types is difficult w ith th e U bbelohde a p p a ratu s. A suitable m ethod of te s t for such greases, w hich will give consistent results, is to ta k e a piece o f wire a b o u t 3 inches long, m ake a sm all loop a t one end, an d th e n coil th e w ire ro u n d th e therm om eter stem an d a d ju s t so th a t th e loop is level w ith th e tip o f th e bulb. A sm all p o rtio n o f th e grease, suffi­

cient to yield th ree or four drops, is th e n fixed in th e loop so th a t i t is in co n tact w ith th e therm o m eter bulb. T he th erm o m eter is th e n placed in a te st-tu b e, w hich is h ea te d in th e usual w ay in a b a th o f oil or glycerol.

T h e d eterm ination o f th e m elting p o in t o f a grease is of g re a t im portance, b u t th e conventional m ethods do n o t alw ays give com plete inform ation of th e results to be expected in service. A useful te s t to em ploy in th is connection is to m ake 15 gram s o f th e grease into a cone in a flat m etal dish—

th e lid of a tin will serve quite well— a n d th e n to place th is in a n oven m aintained a t a tem p eratu re 30-40° F . below th e ap p a re n t m elting p oint o f th e grease. I t will often be found th a t, o f tw o greases having sim ilar m elting points, one will m a in tain its stru ctu re unchanged, w hilst th e o th er will break dow n and flow o u t to a com m on level.

Co n s i s t e n c y.

The only m ethod for th e d eterm in atio n of th e consistency o f a lubricating

grease th a t has received official recognition is th a t em ploying th e p en etro ­

m eter an d procedure described u nder I.P .T . Serial D esignation L.G.18 and

A.S.T.M. D .217-33.T. The use o f th is ap p a ra tu s docs give reproducible

results, a n d i t is exceedingly useful for th e control o f w orks batches an d

for specification purposes. A ltern ativ e m ethods in regular use, such

as th e K arns-M aag, th e m ethod described in A ir M inistry specification

D .T .D . 143. B, a n d su n d ry others em ployed in various w orks laboratories,

have in com m on th e allowing o f a solid plunger to p en e trate th e grease

w hen dropped from a know n height— th e consistency being ta k e n as a

reciprocal fa cto r o f th e d istance to w hich th e plunger sinks below th e

surface o f th e grease.

T ESTIN G OF LU BR IC A TIN G GREA SES. 2 7 9

All these m ethods give results which are n o t com patible w ith those o btained w ith th e I.P .T . a p p aratu s. In v e stig atio n has shown th a t th e difficulty is principally duo to th e fa c t th a t th e cone penetrom eter does n o t respond sufficiently to changes in th e viscosity of th e m ineral oil content of th e grease. F o r exam ple, p articu lars are given o f th e com parative p e n e tra ­ tio n figures obtained w ith th e I.P .T . an d th e D .T.D . 143. B a p p a ra tu s when te stin g tw o greases, of w hich “ A ” is based on 100 P ale Oil, an d “ B ” on 500 R ed Oil. B o th greases were m ade b y th e sam e m ethod an d w ith th e sam e fats, and have identical lim c-soap contents—nam ely

per cent.

All te sts were m ade on th e w orked greases.

I.P .T . M eth o d D .T .D . 143. B M ethod

“ A ” “ B ” “ A ” “ B ”

0° C. (32° P .) . 25° C. (77° F .) . 0 0 ° C. (1 4 0 ° P .)

26-0 m m . 30-0 m m . 34-2 m m .

20-5 m m . 26-5 m m . 31-5 m m .

0 0 in.

1-0 in.

1-45 in.

0-25 in.

0-55 in.

1 1 5 in.

In view o f th e alm ost universal use m ade o f th e I.P .T . a p p aratu s, these results were checked b y ascertaining th e ra te s o f feed of b o th greases a t th e tlireo tem p eratu res from a constant-prcssure-spring grease cup. W hile th e exact figures obtained varied w ith different cups, i t w as obvious th a t th e plunger or D .T .D . 143. B m eth o d gave results which were th e m ore tru ly indicative of th e ra te o f feed. F u rth e r, as th e o u tlet o f th e cup w as a tu b e m easuring

inch in length by J inch in diam eter, it could be considered as a crude form of constant-pressure grease viscom eter. Accordingly, it would appear th a t th e plunger m ethod gives results o f m ore p ractical value th a n th e cone penetrom eter, although th e la tte r is, as sta te d , very useful for checking works batches o f greases m ade from th e sam e oil, and a t th e sam e tem perature.

The D .T.D . 143. B plunger m ethod is th e m ore readily ad aptable, owing to its com pactness, for use a t w idely varying tem p eratu res, and it is, indeed, already in use for th e testin g o f greases a t tem p eratu res ranging from as low as — 50° C. to as high as 100° C. Discrepancies betw een th e A ir M inistry a n d o th e r sim ilar m ethods arise from th e fa c t th a t in th e form er th e tu b e of grease u nder te s t is contained w ithin an o th er tu b e an d th e displaced grease rises round th e plunger, w hilst in th e o th er m ethods th e grease is in an open container giving a com paratively large free surface.

I n th e K arns-M aag ap p a ra tu s th e plunger is spherical in stead of cylindrical, and little heed is ta k e n of th e e x te n t o f th e w orking to w hich th e grease has been subm itted.

W h atev er th e m ethod o f determ ination em ployed, i t is essential th a t th e

grease should be te ste d in th e “ w orked ” condition. The I.P .T . w orker

is perfectly satisfactory. The d eterm ination o f th e unw orked consistency

is o f little p ractical value, a n d in an y case it is difficult to o b tain consistent

figures even w hen using original containers. How ever, th e d eterm in atio n

o f th e ra tio betw een th e unw orked and w orked p en etratio n s does keep a

check on m anufacturers who draw th e ir greases a t ra th e r high tem p eratu res

an d send th em o u t w ith false ap p aren t consistencies. M odern m echanical

greasing devices do thoroughly w ork th e lu b rican t before delivery to th e

2 8 0 W E B B E R : T H E ANALY SIS AND

bearing, a n d it is th e consistency a t th e delivery p oint th a t m atters. I n any case, greases should be prew orked as far as possible during m anufacture for such m ethods of application, in order to ensure th a t as consistent a grease as possible is supplied th ro u g h th e lubricator.

St a b i l i t y a t Hi g h Te m p e r a t u r e s.

D uring recent years increasing intere st has been ta k e n in th e behaviour of lubricating greases a t high w orking tem p eratu res, m ore p articu larly in th e case of lime-soap ball an d roller-bearing greases a t tem p eratu res above th e ir m elting p o in t which would also cause m ore or less com plete dehydration.

T his in terest is justified, b u t the value of such a te s t is n o t so g re a t as it would ap p ear to be from th e am o u n t of discussion which it h as caused. I t m u st be rem em bered th a t a grease is only used for th e lubrication of such bearings w here reten tio n an d p ro tectio n are of p rim ary im portance, an d no grease is deliberately chosen for use a t tem p e ratu res above its m elting point. Accordingly, i t would ap p ear th a t a more, prolonged s ta b ility te s t a t, say, 65-70° C. has m ore practical value, and th is also applies to greases intended for general m achinery lubrication.

T he result o f th e m ore strin g e n t te s t o f subjecting th e grease to a te m ­ p eratu re of 120° C. or over is n o t alw ays correlated to th e sta b ility o f the grease a t m ore norm al w orking tem peratures. Such a te s t has, however, its value, in th a t it does ensure th a t separation will n o t ta k e place if th e grease is overheated for a sh o rt tim e. F o r exam ple, th is could occur in th e event o f p a rticu larly severe overloading, or if th e grease should channel, in which case th e lubricant would n o t be draw n into th e ball grooves u n til sufficient h e a t h a d been generated to m ake th e grease a t least semi-fluid.

As regards th e m ethod o f conducting such h e a t te sts, th a t specified b y Messrs. B ritish Tim ken, L td ., is th e one in m ost common use in th is country.

W hile th is te s t does give useful inform ation, it is som ew hat arb itra ry , and th e m ethod specified by th e W ar D ep artm en t Chem ist, th e A ir M inistry, and th e London Passenger T ra n sp o rt B oard is preferable. I n both m ethods th e tem p e ratu re is practically th e same— nam ely, 250° F . or 120° C.—

an d while th e specified stirring o f th e grease in th e T im ken te s t does ensure more com plete dehydration, th is is balanced by th e fa c t th a t th e alte rn ativ e m ethod specifies heating a t 1 hour in stead o f th e T im ken half-hour.

I n th e case o f th e T im ken te s t th e grease m u st re-set h a rd enough to allow o f its reten tio n in th e silica tu b e by th e cross wires, and a d eh y d rated grease which sets to a h a rd gel will usually break dow n rap id ly w hen su b ­ jecte d to ag itation. On th e o th er hand, m any greases w hen subjected to th is h eat te s t will re tu rn to a softer and m ore greasy gel w hich is m ore stable on ag itatio n , a n d these pass in a m ore satisfacto ry m anner th e alte rn a tiv e tost. F rom th e p oint of view o f th e w orks chem ist, th e T im ken te s t requires m ore tim e a n d m anipulation th a n does th e te s t used b y th e G overnm ent D ep artm en ts, w ith o u t giving a n y m ore useful inform ation, an d th is is o f some im portance where a num ber of batches have to be tested each day.

St a b i l i t y a t No r m a l Wo r k i n g Te m p e r a t u r e s.

As regards s ta b ility te s ts a t m ore norm al w orking tem p eratu res, th e

original p ractice was to h ea t

gram s o f th e grease in a porcelain dish in an

TE S T IN G O F LU B R IC A TIN G GREASES.

oven for 24 hours a t 70° C. R ecently th is te s t has been extended to periods of over a w eek, a n d useful inform ation has been gained.

A p a rt from lime-soap greases, h e a t te sts of high-m elting-point soda-soap greases a t tem p eratu res below th e ir m elting points are definitely equally as im p o rtan t. These are norm ally carried o u t for periods of u p to 24 h o u rs’

heating a t tem p era tu res o f 100° C. or 150° C., according to th e m elting p o in t o f th e grease an d its intended application. I t is essential th a t th e grease should n o t h ard en excessively or sep arate oil, a n d m uch useful inform ation can be gained by observation o f th e consistency a n d stru ctu re o f th e grease a fte r heating a t these tem peratures.

I n th e case of high-m elting-point block-greases, explanation o f surprising differences in consum ption can be found b y placing cubes o f th e grease on, say,

-mesh wire gauze and h eatin g a t 300° F . in a n electric oven. I t will som etim es be found th a t a block-grease will b reak dow n an d percolate th ro u g h th e gauze a t lower tem peratures th a n a n o th er block-grease of nom inally lower m elting point.

St a b i l i t y a t Hi g h Pr e s s u r e s.

All com pound lubricating greases ten d -to separate oil if exposed to high pressures for len g th y periods, an d it has been necessary to develop m ethods o f te s t in order to effect th e necessary im provem ent in greases for use in spring pressure cups an d m odern high-pressure greasing equipm ent.

My own practice is to m ake use o f tw o devices, th e first being a n o rdinary spring pressure cup w ith a cap over th e orifice, so th a t pressure can be m aintained for an y desired period, and th is has th e ad v an tag e o f reproduc­

ing th e ex act conditions o f use. T he o th e r device is a steel tu b e | inch d iam eter a n d 4 inches long, w ith a screw cap a t each end to facilitate filling and e m p ty in g ; one cap is fitte d w ith an ordinary nipple for a liand-greasc gun. The tu b e is filled w ith th e grease, th e caps securely tig h ten ed , a n d pressure is th e n exerted by applying th e hand-gun to th e nipple. The tu b e can either be filled to capacity or air space allowed so th a t th e effect of m aintaining th e grease in co n tact w ith a ir u n d er pressure can also be observed. F o r high-tem perature w ork th e cap or tubo can be placed in an electric oven.

I t has been found possible to reduce separation of oil to negligible p ro ­ portions in th e case o f lim e-soap greases an d stiff d eh y d rated soda-base greases, b u t soft fibrous lubricants will alm ost alw ays show appreciable separation.

St a b i l i t y o n St o r a g e.

I t is essential th a t a lubricating grease should be capable of being stored eith e r in a tra d e container or in a bearing for periods o f a t least six m onths, w ith o u t deterioration, which m ay be due to a n y or all of th ree factors—

oxidation, developm ent of acidity, or separation o f th e m ineral oil com­

p onent. O f th e th ree th e la tte r is usually th e m ost troublesom e.

I n general, it has been found th a t sta b ility during storage is closely allied to sta b ility of th e grease w hen subjected to high pressure in co n tact w ith a ir, a n d th e pressure tu b e previously described has been used in th e develop­

m en t of stable greases. Also, a prolonged h e a t te s t— say, seven days a t

70° C.-—gives useful inform ation. One can safely say th a t a grease w hich

2 8 2 W E B B E R : T H E A N A LY SIS AND

shows no appreciable separation o f oil, oxidation, or increase in a cid ity w hen su b m itted for one week to th e pressure an d h e a t te sts, will re ta in its characteristics w ith o u t d eterio ratio n for a t least tw elve m onths in storage, an d probably considerably longer.

O ther te sts consist o f centrifuging th e grease, or o f observing th e am o u n t of oil ex trac ted by cap illarity w hen th e grease is placed in co n tact w ith filter-paper. The first o f these is of no g re a t value, as th e separation o f oil during storage is n o t due to th e force o f g rav ity , a n d th e second does n o t give reproducible results. N eith er te s t gives a n y evidence o f resistance to oxidation or acid form ation.

N atu rally , sam ples o f grease should be k e p t in storage both in th e usual containers an d in bearings, a n d be exam ined a t regular intervals for any evidence of deterio ratio n in order to confirm th e results o f accelerated lab o rato ry tests.

Lo a d-Ca r r y i n g Ca p a c i t y.

T he m ost convenient ap p a ra tu s for th e determ in atio n o f th e load-carrying cap acity o f a lubricating grease is th e T im ken L u b rican t T esting Machine.

E x c e p t in th e case o f greases having definite E .P . properties, i t is b est to ru n th e m achine a t 400 r.p.m .— i.e., 200 feet p er m inute ru b b in g speed—

in stead of th e m ore usual 800 r.p .m ., and it is th e n possible to o b ta in reproducible results o f g reat value for com parative purposes.

I n th e case o f lim e-soap eup-greases i t is found th a t load cap acity in ­ creases w ith increasing soap content, especially in th e case o f those m ade w ith wool stearine, doubtless due to th e presence of wool w ax. In all cases th e efficiency o f th e grease is m uch g reater th a n th a t of th e basic oil. In th e case o f soda-soap greases th ere is less v ariatio n w ith soap content, although th e load cap acity is still m uch g reater th a n t h a t o f th e m ineral oil content. Some ty p ical results are given below.

A p p ro x im a te C om position. T im k e n O .K . V alue.

Oil C o n ten t. S oap C o n ten t. L ev e r L o ad .

P e r c en t. P e r c en t. lb.

100 P alo . L im o S oap.

100 ^— 17

87 12 33

81 18 37

75 24 40

500 R ed . L im e Soap.

100 ^— 21

89 10 36

84 15 41

100 P alo. S o d a Soap.

80 20 31

70 30 33

500 R ed . S o d a Soap.

80 20 35

B rig h t S tock. S o d a Soap.

85 15 38

T he Cornell (Faville-Levally) M achine is o f no use for testin g greases,

b u t these results w ith th e T im ken M achine m ay be com pared w ith te sts on

th e Alm en M achine m ade b y E v an s (I.M ech.E. “ Discussion on L u b rican ts ”

T ESTIN G O F LU B R ICA TIN G GREA SES. 2 8 3

1937). I t is w o rth y of note th a t in th e case o f th e T im ken M achine th e te st- pieces are subject to a copious flow of oil, b u t w ith greases only a sm all supply is fed from th e screw-down lubricator, an d tem p eratu res o f th e te st- pieces are correspondingly high. The figures quoted also agree w ith th e s ta te m e n t m ade b y Garlick (./. In stn Petrol. Tech., 1934) to th e effect th a t o rdinary cup-greases m ade w ith lig h t spindle oils will give acceptable results under service conditions in w hich th e lubricating oil alone would prove unsatisfactory.

S atisfactory extrem e pressure greases for anti-friction bearings in rolling- mills are m ade b y incorporating sulphurized f a tty oil in a lead-soap-base grease, an d lever-load capacities up to 70 lb. a t 800 r.p.m . on th e T im ken M achine can be obtained. Lime- and soda-soap greases can also be tre a te d w ith sulphur an d chlorine com pounds to give equal load capacities w ith , in some cases, g reater sta b ility th a n th e lead-soap products. The difference betw een th e tw o lies principally in th e fa c t th a t th e lead soap-sulphur greases m ore readily resist shock-loading w ith o u t scoring, and w hen running te sts a t near th e breakdow n points th is is o f im portance, as w eights o f 60-70 lb. can be easily applied a little too roughly.

W ear te sts can also be carried o u t using th e T im ken M achine— th e w ear being m easured bo th b y th e w idth of th e scar on th e block an d th e loss in w eight o f block an d cup.

Low

R equests are som etim es m ade for inform ation concerning th e “ cold te s t ” o f a grease, an d i t can be said th a t i t is roughly equivalent to th e p o u r­

p o in t o f th e m ineral oil for soap contents up to approxim ately 12J p er cent.

F o r higher concentration o f soap th e re is a definite increase, w hich varies w ith th e oil, soap stock, w ater content, etc.

P en etratio n te sts a t low tem p eratu res can be readily carried o u t using th e plunger-type a p p aratu s described in A ir M inistry Specification D .T.D . 143. B. I n m ost cases th ere is a stea d y decrease o f p e n e tra tio n w ith fall in te m p eratu re u n til i t becomes negligible. F u rth e r inform ation o f th e resistance due to stiffening of th e grease a t low tem p eratu res can be obtained b y m aking use o f th e a p p aratu s described in A ir M inistry Specification D .T .D . 201, w hich consists essentially o f a steel ball ro ta te d in a brass socket by m eans o f w eights an d pulleys. H ere th e tem p eratu re a t which th ere is a m arked increase in th e tim e ta k e n for ro ta tio n of th e ball is usually q u ite definite, and th e cold te s t can be rep o rted to w ith in 5° C.

However, except for exceptional conditions o f service, it is usually suffi­

cient th a t th e grease shall be easily w orkable a fter exposure to 0° C. for, say, 2 hours, a n d th is stip u latio n is em bodied in a num ber of specifications.

I t is reg retted th a t lack o f tim e p revents giving m ore precise details o f th e various te sts a n d th e ir form ation in to a com plete progressive scheme of grease analysis. Also, i t has n o t been possible to include details o f specific te sts m ade w ith greases destined for specialized applications—for exam ple, w ater-pum p greases, w heel-bearing greases, steering-gear greases, universal jo in t greases, etc.

T he a u th o r’s th a n k s are due to Mr. L. A. Phillips, who h as carried o u t

m ost o f th e te sts to w hich reference is m ade.

2 8 4

A

of tho In s titu te of P etroleum was held a t th e H ouse o f the R oyal Society of A rts, J o h n A dam S treet, London, W.C. 2, on T hursday, 22nd F eb ru ary , 1940, a t 5.30 p.m . Mr. E . A. E v an s, F .In s t.P e t., M .I.A .E., occupied th o Chair.

The C hairm an, in introducing Mr. M. W . W ebber, said th a t th e paper which was being read th a t evening was in v ited before tho w ar commenced.

Tho in v itatio n was m ade w ith th e express in te n tio n o f producing a dis­

cussion up o n th e possibilities of standardizing te sts for grease. T he I n s titu te h a d stan d ard ized te sts for petroleum products, an d h ad included a few te sts for grease. Tho Council was o f th e opinion th a t greases should now receive fu rth er consideration.

Mr. W ebber’s paper w ould servo as a fo undation stone upon w hich th e stan d ard izatio n of greaso te stin g could be erected. Mr. W ebber was know n to m any as a specialist on grease, a n d a m em ber of tho Grease P an el of tho In s titu te .

T he following p a p e r w as th e n re a d :—

“ The Analysis a n d T esting of L u b ricatin g Greases ” b y Mr. M. W . W ebber. (See pages 273-83.)

D IS C U S S IO N .

Th e Ch airm a n sa id t h a t m em b e rs w o u ld a p p re c ia te th e reaso n s fo r th o lim ite d s u p p ly of p re -p rin ts . H o know t h a t i t w as difficult to m a rs h a ll a ll th o fa c ts as th e p a p e r w as bein g re ad .

M r. W eb b e r h a d su g g este d th e e s tim a tio n of u n sap o n ifiab les b y o x tra c tio n w ith aceto n e. T h e m e th o d w as sim p le, a n d a c c u ra te to 1 p e r c e n t.

H o also su g g ested to lu en o e x tra c tio n , su b s e q u e n t to aceto n o e x tra c tio n , fo r th e e stim a tio n of so ap s. T h e resid u e, a f te r th o e x tra c tio n s , w as fillers, m ica, g ra p h ite , a n d o th e r solid ad d itiv es.

N o d o u b t m em b ers w ould e x p ress th e ir o p in io n s o n th es e m e th o d s. I f su c h m e th o d s w ere s a tis fa c to ry , th e y w o u ld be v e ry a ttr a c tiv e .

M r. W e b b e r s ta te d t h a t in so d a-so ap greases b o th freo f a t a n d free a lk a li m ig h t bo p re s e n t. T h erefo re in th o e stim a tio n of th e freo a lk a li th o alcoholic so lu tio n sh o u ld n o t bo boiled. M em bers w ould p ro b a b ly re m e m b e r t h a t in “ S ta n d a rd T e s ts ” a sim ila r w a rn in g w as g iven.

T ho dim en sio n s of th e U b b elohdo a p p a ra tu s , w h ich a re g iv en in “ S ta n d a r d T e s ts ,”

w ere th o re s u lt of carefu l c o n sid era tio n b y th e I n s titu te . F o r th e p u rp o se s of th o B ritis h P h arm aco p o eia, i t w as fe lt t h a t th o a c tu a l th ic k n e ss of m a te ria l in th e c u p sh o u ld b e specified. A t first i t a p p e a re d to th e B ritis h S ta n d a rd s I n s titu tio n t h a t to s ta n d a r d ­ ize th o in te rn a l dim en sio n s of th e cu p a s w ell a s th o o x te m a l m ig h t le a d to m a n u ­ fa c tu rin g difficulties. A n y serious m o d ific atio n of th o p ro se n t a p p a r a tu s m ig h t easily lea d to difficulties in th e p e tro le u m w o rld . H a p p ily , a g ree m e n t w as re ac h ed on b o h a lf of th e I n s titu to of P e tro le u m a n d th e B ritis h P h arm aco p o eia. I t w as b elieved t h a t th e B .S. a p p a r a tu s w o u ld bo sa tis fa c to ry to m em b ers of th e I n s titu to . I t m ig h t bo p ru d e n t to re m in d m em b e rs t h a t th o B ritis h P h arm aco p o eia c o n ta in ed leg al s ta n d a rd s .

M r. W eb b e r s ta te d t h a t w o rk ed sam p le s w ere in fin ite ly m oro im p o r ta n t th a n u n ­ w o rk ed . I f t h a t w as th o case, w ere th e y n o t w a s tin g th e ir tim e te s tin g u n w o rk ed sam p les ? A defin ite lea d w as re q u ire d o n t h a t p o in t.

T h e I n s titu to d efin itely w a n te d a le a d fro m th o m em b e rs o n th o q u e stio n of s ta n d a r d ­ iza tio n of greaso te s ts . I t w as th e re fo re im p o r ta n t t h a t m em b e rs sh o u ld g iv e th e ir view s freely.

T H E I N S T I T U T E O F P E T R O L E U M

D ISCU SSIO N ON A N A LY SIS AN D T E S T IN G O F LU B R IC A T IN G G R E A SES. 2 8 5 Dr. E . R . R e d o r o v e sa id th o m ooting w as a v e ry im p o rta n t one, because i t w as th o first w hich th o I n s t i tu t e h a d h e ld since th o w a r b ro k e o u t. . T h e largo a tte n d a n c e w as a cloar in d ic a tio n , h e th o u g h t, t h a t th e m eetin g s of th o I n s t i tu t e sh o u ld c o n tin u e to b e h e ld in sp ite of th o w ar.

T h e m em b ers woro m u c h in d e b te d to Mr. W eb b e r fo r h is p a p e r. A lth o u g h i t h ad b e en c o n te m p la te d la s t A u g u s t, ho d id n o t supposo t h a t i t h a d b e en w r itte n befo re th e w a r b roke o u t, a n d m a n y m em b e rs kn o w h o w b u sy M r. W eb b e r m u s t h a v e b e e n since t h a t d a y . I t to o k a g r e a t d e a l of tim e to w rite a n y p a p e r, a n d M r. W eb b e r m u s t h a v o d e v o te d a g re a t d e al of tim e a n d th o u g h t to b rin g o u t w h a t seem ed to h im som e v e ry im p o rta n t p o in ts , w h ich h e h o p ed w ould b e fu lly d iscussed la te r on.

H e d id n o t propose to m ak e a n y c o m m e n ts on a n y th in g w h ich M r. W eb b e r h a d sa id specifically, b u t h e w ished to re fe r to th o n ecessity of sta n d a rd iz in g te s ts . I t w as th e fu n c tio n of th o I n s titu te , ho th o u g h t, to ta k e ch arg e of tho m a tte r , a n d n o t to allow' a s ta to of ch ao s to com e in to bein g in w hich d iffere n t in te re s ts eac h h a d th e ir ow n p e t id eas o n te s tin g to w h ich th e y e x p ec te d m a n u fa c tu re rs to a d h e re . I f a n y b o d y w as to in v e s tig a te a n y q u e stio n c o n n ec te d w ith th e te s tin g of p e tro le u m p ro d u c ts in th o b ro a d e st sense, ho th o u g h t t h a t t h a t b o d y sh o u ld be th e I n s t i tu t e of P e tro le u m .

T h e I n s titu te h a d its S ta n d a rd iz a tio n C o m m ittee, a n d h e w as co n fid en t t h a t th e discussion to follow w ould givo to t h a t C om m ittee a good in d ic a tio n of w here rev isio n or re s ta n d a rd iz a tio n of gre ase te s ts w as called for.

I n conclusion, h e w ished to th a n k M r. W eb b e r for h is v e ry v a lu a b le a n d in te re s tin g p a p er.

Dr. E . R . S t y i . e s sa id thoro w as one p o in t t h a t ho th o u g h t m ig h t bo m ad o re g ard in g th e con sisten cy . H o fe lt t h a t th e I .P .T . m e th o d w ould co v er a w id e r ra n g e of greases m ore sa tis fa c to rily th a n th e D .T .D . 143 m e th o d . I t h a d b e en found t h a t w ith v ery so ft greases th e I .P .T . m e th o d co u ld s till bo a p p lie d , w h ereas w ith th o A ir M in istry m e th o d th o p lu n g e r w ould p e n o tra to rig h t to th e b o tto m of th o c o n ta in e r. I n th o p a p e r, a tte n tio n h a d b een d ire c te d to th o re la tiv e ly sm all difference in th o n u m erica l v a lu e of th e c o m p a ra tiv e te s ts w ith th o tw o greases “ A ” a n d “ B ” in th e case o f th o I.P .T . m eth o d , a n d th o re la tiv e ly largo difference betw een th e sam e tw o greases w hen te s te d b y th o A ir M in istry m e th o d . H e th o u g h t t h a t , if it w as re m e m b e re d t h a t in one easo a conical p e n e tra to r w as u se d a n d in th o o th e r a c y lin d e r of sm a ll cross-sectional a re a , th o re aso n fo r t h a t u n fa v o u ra b le co m p ariso n w ould bo b e tte r a p p re c ia te d .

W ith re g ard to M r. W eb b e r’s co m m e n ts in re la tio n to th e w o rk in g of greases d u rin g m an u fa ctu re , th e m ee tin g m ig h t like to h e a r of a n ex p erien ce w hich he h a d som e y e a rs ago, w h en en g ag ed in th o a c tu a l m a n u fa c tu re of g re ase s. H o h a d occasion to n o tic e v e ry big d iscrep an cies in th e a p p a r e n t c o n sisten cy of sam p les s u b m itte d to h im b y th e w orks fro m w h a t w ere alleged to b e b a rre ls of greaso ta k e n fro m th e sam e b a tc h . W h en th e m a tte r w as in v e s tig a te d , it w as fo u n d t h a t th o r a te o f cooling of th o grease influenced th o p e n e tra tio n o b ta in e d , e v en th o u g h t h a t te s t w as m ad e a fte r w ork in g b y th o I .P .T . m e th o d . T h u s it w a s fo u n d t h a t a sa m p le d ra w n fro m th e o u tsid o of a b a rre l g av e a v e ry stiff greaso as th o re s u lt of th o ra p id cooling, w h ereas one d ra w n fro m th e c en tre s u b je c t to v e ry slow cooling w as m u c h so fter. T ho p o in t re g ard in g p re-w o rk in g d u rin g m a n u fa c tu re to en su re u n ifo rm ity a p p e a le d to h im v ery stro n g ly , because th e re w as a g re a t d eal of d ifficulty in co n v in cin g cu sto m ers t h a t th e y h a d a s a tis fa c to ry grease w h en th o y fo u n d t h a t from one p a ck ag e th e y co u ld g e t d ifferen t te s t re su lts a cco rd in g to th o p o in t from w hich th e sa m p le w as ta k e n .

Tile Ch a ir m a n a sk ed w h e th e r D r. S ty les co u ld m a k e a n y su g g estio n w ith re g a rd to th o m a tte r from th e in sp ectio n p o in t of view .

Dr. S t y l e s sa id t h a t of course th o grease h a d b e en d ra w n off in to th e c o n ta in e rs a t a re la tiv e ly high te m p e ra tu re . H e th o u g h t th e m ore m o d e m m e th o d w as to allow th e grease to re a c h so m e th in g a p p ro ac h in g a tm o sp h e ric te m p e ra tu re in shallow tr a y s , a n d th e n to sh o v el it o u t in to th o final p ack ag e. I n th e case t h a t ho h a d q u o te d th e m a te ria l w as p o u re d in to th e c o n ta in e r a n d th e n allo w ed to cool— a v e ry slow process w h en w ooden b a rre ls w ere u sed , lead in g to a b ig difference in r a te of cooling betw een th o c e n tre a n d o u te r p a r t of th e b a rre l. H o w a s g o ing b a c k som e y ears, b u t, if his m em o ry se rv ed h im a rig h t, th o figures w ere of th o o rd e r of 200 o n th o o u te r m a te ria l a n d 300 o n th o in n er m a te ria l b y th e A .S.T.M . m e th o d ; t h a t w a s o n a m ed iu m cu p grease.

T ho sam p les wore w o rk ed w h en th e y re a c h ed th e lab o ra to ry .

2 8 6 D ISC U SSIO N ON ANALY SIS AND T ESTIN G OF LU B RICA TIN G G R EA SES.

Tile Ch airm a n : A n d th o y s till v a rie d ? Dr. S t y l e s : Y es.

Mr. F . J . S. H a l l sa id ho w elcom ed th e p a p e r b ecau se i t seem ed to h im t h a t h ith e rto no serious in te r e s t h a d b een ta k e n in lu b ric a tin g greases b y th o h ig h er te c h n ic a l m in d s engaged in th o p e tro le u m in d u s try . H e th o u g h t t h a t w as a p ity , becau se th o s u b je c t w as a v e ry im p o r ta n t one, a n d ho h o p ed t h a t M r. W e b b e r’s p a p e r w ould b e g iv en as m u ch p ro m in en ce as possible. H ith e r to h e believ ed th e b all-b ea rin g m a n u fa c tu re rs h a d to be th a n k e d fo r e n fo rcin g g re a te r a tte n tio n to th e a ca d em ic side of g rease-m ak in g . T ho C h airm an h a d re fe rre d to th e q u e stio n of a ce to n e e x tra c tio n for th e oil a n d free fa t.

P e rso n a lly h e th o u g h t t h a t w as a n e x tre m e ly good m e th o d a n d w as one t h a t h e h a d o fte n u se d him self. I t w as p ro b a b ly b e tte r e a rn e d o u t in a S te v en s e x tr a c tio n a p p a r a tu s t h a n in a S o x h le t, a n d th e greaso m ix e d w ith p re v io u sly e x tr a c te d sa w d u s t o r sim ila r m a te ria l boforo b e in g p lac ed in th e th im b le . T h e o n ly p o in t in th o p a p e r w hich ho w ish ed to criticize w as th o q u e stio n of a c id ity in th o grease. H o co u ld n o t agree w ith Mr. W eb b e r’s sug g estio n of 1 p e r co n t. bein g a d esirab le fig u re ; h e th o u g h t th at;

d e sid e ra tu m sh o u ld be n e a re r 0-1 p e r c ont.

Mr. H . W . Ciie t w in said h e w ished to th a n k M r. W eb b e r fo r th o v e ry lucid, concise, a n d in te re s tin g p a p o r t h a t h a d b e en p re s e n te d t h a t evening. H o d id n o t th in k tho C h a irm a n h a d been q u ito fa ir to M r. W e b b e r in su g g estin g t h a t a ll th e te s ts d escrib ed in th e p a p e r w ere o x trem e ly s im p le ; M r. W e b b e r co u ld p ro b a b ly ag ree t h a t t h a t w as n o t re a lly th o caso. T h ey b e ca m e sim p ler, of course, w ith c o n s ta n t u se, b u t th e y n ecessarily re q u ire d e x p erien ce a n d care.

T ho p a p e r co v ered th e g ro u n d so th o ro u g h ly , in his o p inion, t h a t th e re w as v e ry little ro o m for criticism . I t w as in te re s tin g to co n sid er t h a t th e te s ts h a d b e en b u ilt u p , o r p e rh a p s it w o u ld bo b e tte r to sa y s ta n d a rd iz e d , o v e r a c o m p a ra tiv e ly s h o rt p e rio d — i.e., w ith in th e la s t tw e n ty -fiv e y e ars— w hich w as n o t a v e ry long tim e to look b a c k u p o n , th o u g h i t seem ed a good w hile in th e fu tu re . T w en ty -fiv e y e a rs ago v e ry little a tte n tio n w as p a id to te s ts of lu b ric a tin g grease. I n fa c t, th o av era g e co n su m er h a d o n ly tw o w h ic h ho ap p lie d , a n d tho so tw o te s ts M r. W eb b e r h a d n o t th o u g h t it d e sirab le to m e n tio n in h is p a p e r. T h e first w as th e co lo u r te s t, w hich w as q u ito easily m ad e . T ho p ro sp e c tiv e b u y e r lo o k ed a t th o greaso, a n d if it w as of a c olour t h a t s u ite d his ¡esthetic feelings, th e greaso w as s a tis fa c to ry ; othcrw iso i t w as n o t. T h e o th e r te s t m ig h t b e briefly d e scrib e d as th o th u m b -a n d -fin g e r te s t, w hich p e rh a p s d id n o t n eed a n y f u r th e r e x p la n a tio n .

Sinco t h a t tim e th e re q u ire m e n ts of en gineers a n d of m o d ern p la n t h a d n e ce ssitate d a m u c h g re a te r know ledge o n th e p a r t of th e consum er, a n d th o g rease-m ak ers h a d h a d to a p p ly th em se lv es to th o m a n u fa c tu re of p ro d u c ts w hich w o u ld g iv e r e s u lts n e v er a n tic ip a te d in th e e a rly d a y s, a n d gre ase h a d , in d eed , com e in to its ow n once m ore.

T h e specifications t h a t woro n ow d ra w n u p w ere fre q u e n tly n o t p re p a re d b y c h em ists w ho w ere a c q u a in te d w ith th e p rin cip les of th e m a n u fa c tu re of grease, w ith th o re s u lt t h a t specifications o fte n in clu d e d ite m s w h ich w ere e n tire ly in co m p a tib le — a defin ite p ro p o rtio n of so a p a n d a c e rta in a m o u n t of a s h w h ic h w as m u ch to o low for t h a t p ro p o rtio n , a n d re q u e sts fo r m o ltin g p o in ts of lim e-soap greases w h ich w ere f a r b ey o n d th e h ig h est e x p e c ta tio n s o f th e sa lesm a n . T h e re w as also, ho fo u n d , a te n d e n c y a m o n g s t th o se w ho w ere resp o n sib le fo r th o specifications to t r y to do a little b e tte r ev ery tu n e . T h ere w ere one o r tw o w ell-know n c o n su m ers w ho w ere c o n s ta n tly tig h te n in g u p th e ir specifications, w ith a view to seeing h o w m u c h b e tte r, in th e ir viow, th e greaso co u ld be— so m e tim es w ith so m e w h a t u n fo rtu n a te re su lts.

H e w ished to ta k e u p th o C h a irm a n ’s ch allen g e w ith re g a rd to th e U b b elohdo a p p a ra tu s , w hich h e con sid ered a m o st u n s a tis fa c to ry a p p a r a tu s to use fo r ta k in g a m e ltin g p o in t. T h e r e s u lts v a rie d v e ry m u c h in th e h a n d s of d iffe re n t o p e rato rs, duo, as M r. W eb b e r h a d p o in te d o u t, to th e d ifficu lty of g e ttin g th e cu p sta n d a rd iz e d . A lso, th ere w as th o v e ry g re a t d ifficu lty of e n su rin g t h a t th ero w as n o a ir o cclu d ed in th e grease. A p ra c tic e w h ich h e h a d fo u n d s a tis fa c to ry in t h a t co n n ec tio n w a s to p ress th e greaso th ro u g h a v e ry fine m esh b efo re it w as p u t in to th e c u p , b u t e v en w h en t h a t w as d o n e i t w as fo u n d t h a t a n u m b e r of re s u lts v a rie d v e ry co n sid erab ly , a n d it seem ed t h a t c e rta in o p e ra to rs in v a ria b ly o b ta in e d a d ifferen t re s u lt— t h a t w as to sa y , e ith e r a c o n siste n tly h ig h er o r a c o n siste n tly low er r e s u lt th a n th e re s u lts o b ta in e d b y o th e r o p e rato rs.

DISCUSSION ON ANALYSIS AND TESTING OF LUBRICATING GREASES. 2 8 7 Mr. A . T . WILFORD, referrin g t o Mr. C h otw in ’s rem ark s, sa id t h a t h e h im s e lf h a d re-d ra fted a n d r e v ise d m a n y sp e c ific a tio n s, a n d h a d n o v e r .c o n sc io u sly d on o so w ith a v ie w to a sk in g for so m e th in g t h a t c o u ld n o t b e su p p lie d . W h a t h e h a d g e n e r a lly d o n e w a s to se le c t th o b e s t s u p p ly o b ta in e d fro m a n u m b e r o f so u rc es a n d t o tr y to b ring a ll th o m a n u fa ctu rers u p t o t h a t lo v e l, a n d t h a t sh o u ld g iv e n o c a u se o f c o m p la in t t o a n y b o d y .

W ith regard to t e s t s o f g rea se, o n e t h a t ho h a d fo u n d v e r y u se fu l w a s th e p e n e tr a tio n t e s t , a n d in co n n e c tio n w ith t h a t t e s t th e re w a s o n e d iffic u lty t h a t ho en co u n te r e d a s a user— n a m e ly , t h a t i t w a s o fte n d esired t o e x a m in e th o p r o p e r tie s o f a u sed grease, b u t th e re w a s n o t en o u g h m a te r ia l to carry o u t tho t e s t . I f th e r e w a s sta n d a r d iz a tio n an d a p o ss ib ility o f d e a lin g w ith sm a ller q u a n titie s o f m a te r ia l, i t w o u ld bo v e r y u sefu l.

H e h a d u se d t h e U b b o lo h d o m e ltin g -p o in t m e th o d for so m e y ea rs, a n d i t h a d a t le a s t k e p t h im o u t o f tro u b le .

W ith regard to s ta b ility , h e th o u g h t th o t e s t la id d o w n in th o L o n d o n T r a n sp o rt sp e c ific a tio n w a s c e r ta in ly o f so m e v a lu o a n d h e a p p lie d i t reg u la rly . W h e th e r it co rresp o n d ed w it h a c tu a l se r v ic e c o n d itio n s ho w a s n o t suro, o n e greaso o f w h ich ho h ad u sed v e r y largo q u a n titie s h a d c o n sis te n tly fa ile d to m e e t t h e sp e c ific a tio n , b u t i t w a s m a n y y e a r s b efore it w a s d isco v e red t h a t th e r e w a s a n y th in g w r o n g w ith th e se r v ic e b eh a v io u r o f t h a t greaso, a n d th e n it w a s n o t v e r y serio u s. T h e s t a b ility t e s t d id p erh a p s h a v o so m e r e la tio n t o th o p erfo rm a n ce o f a grease in w h e e l b ea rin g s a n d it w a s in t liis a p p lic a tio n t h a t th o p a rticu la r g rea se to w h ic h ho h a d ju s t referred h ad e v e n tu a lly g iv e n tro u b le , th u s con firm in g th o r e su lts o f th o la b o r a to r y te s t , w h ic h in d ic a te d t h a t th o greaso d id n o t m e e t t h e sp ec ifica tio n .

T h e C h a ir m a n a sk e d Mr. W ilfo r d w h eth er h e th o u g h t it w a s n o t n ocossary to sta n d a r d iz e a n y th in g o n s t a b ility .

M r. W i l f o r d sa id ho d id n o t th in k so . H e r a th er lik e d th o to st to w h ic h ho h a d referred, b u t, a s h o h a d p o in te d o u t, h e h a d n o t a n y c erta in p roof t h a t i t co rre la ted v e r y w e ll w ith a ll se r v ic e c o n d itio n s. I f h e a t a n d pressu re c o u ld bo c o m b in e d in o n e t e s t i t w o u ld b e a g r e a t a d v a n ta g o .

Mr. Ha l l sa id h o h a d b een in te r e ste d a n d su rp rised to h ea r t h a t Mr. W eb b er fo u n d th o a c e to n e e x tr a c tio n m e th o d a lw a y s sa tisfa c to r y . S o m e y e a r s a g o ho h a d h a d t o t e s t u n iv e r sa l jo in t groases, w h ic h g e n e r a lly h a d a s o d a b a se, th o u g h a c erta in n u m b er h ad a lim e b a se , a n d h e h a d n o t fo u n d th e a c e to n e e x tr a c tio n m e th o d a t a ll sa tisfa c to r y . H o h a d b een p a r tic u la r ly in te r e ste d in th e p ro p e r tie s of th e o ils se p a r a ted from th o greaso, b u t i t h a d p r o v e d a b s o lu te ly im p o ssib le , a t a n y r a te w ith in h is ow n oxporionco, to g e t th o o il freo from a sh o r so d iu m or c a lc iu m , a s t h e ca se m ig h t be.

H o h a d tried c en trifu g in g a n d th e u so o f a c id m a te r ia l, b u t t h e sa m e tr o u b le h a d b een e x p erien ced , a n d in t h e e n d h o h a d fo u n d th e A .S .T .M . m e th o d , m o d ified for large- sc a le wrork, w a s m u c h th o b e st.

A n o th e r p o in t ho w ish e d to m e n tio n w a s in r e la tio n to th e d a rk -co lo u red g rea ses w h ic h woro u su a lly h a n d le d in th o u n iv e r sa l jo in t co m p o u n d s. H e d id n o t th in k Mr.

W eb b er h a d m e n tio n e d th e A .S .T .M . m e th o d , in w h ic h th o d ark -colou red g rea ses w ero tr e a te d w ith a c id p o ta ssiu m su lp h a to in p la c o o f th o ord in a ry tr e a tm e n t w it h h y d r o ­ ch lo ric a c id . H o h a d fo u n d t h a t m o th o d so s a tis fa c to r y t h a t h e h a d a d o p te d i t for a ll g rea ses, lig h t co lo u red a s w e ll as dark co lo u red .

H o h ad e x p e r ie n c e d c o n sid er a b le d iffic u lty , w ith d a rk -c o lo u r ed o ils, in g e t tin g a v e r y s a tisfa c to r y a c id v a lu e b y titr a tio n m e th o d s. H e w o u ld lik o t o k n o w w h e th e r Mr. W eb b er h a d h a d a n y e x p e r ie n c e o f th e eleetro m o tric m e th o d s w h ic h h a d b een u se d in A m e r ic a in r e c e n t y ea rs.

T h e C h a ir m a n sa id t h a t h e th o u g h t t h a t Mr. H a ll f e lt th o A m erica n s h a d b een so m e w h a t ig n o red . I t w a s fittin g , th erefore, t h a t m em b er s sh o u ld b e rem in d ed t h a t th o I n s tit u to o f P e tr o le u m h a d a d o p te d , w h erev e r p o ssib le , th o A .S .T .M . s ta n d a r d m o th o d s. C o n se q u e n tly , w h e n w o referred t o t h e I n s tit u to sta n d a r d m e th o d s , w e a lm o st a u to m a tic a lly referred t o t h e A .S .T .M . sta n d a rd s.

M r. H e W a e l e sa id t h a t h is rem ark s w o u ld sc a r c e ly b e v e r y c o n str u c tiv e , a s h e h ad n o sp e c ia l k n o w led g e o f th e in d u s tr y . H e w o u ld , h o w e v e r , lik e to ta k e th e o p p o r tu n ity o f in q u ir in g a s to t h e p recise n e c e s sity for th o m ea su r e m e n t o f c o n s is te n c y o f g rea ses