Screen analysis as an aid in pulp evaluation

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Material Information

Title:
Screen analysis as an aid in pulp evaluation a resume of work at the Forest Products Laboratory
Series Title:
Report ;
Physical Description:
11 p., 11 leaves of plates : ill. ; 26 cm.
Language:
English
Creator:
Schafer, E. R ( Earl R )
Forest Products Laboratory (U.S.)
University of Wisconsin
Publisher:
United States Dept. of Agriculture, Forest Service, Forest Products Laboratory
Place of Publication:
Madison, Wis
Publication Date:
Edition:
Rev.

Subjects

Subjects / Keywords:
Pulpwood -- Evaluation   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references (p. 11).
General Note:
Caption title.
General Note:
"Revised November 1939"--Cover.
General Note:
"In cooperation with the University of Wisconsin"--Cover.
Statement of Responsibility:
by E.R. Schafer.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029560166
oclc - 757733743
System ID:
AA00020710:00001

Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Screen analysis of insulating board stocks
        Page 1
    Screen analysis of groundwood pulp
        Page 2
        Page 2-1
        Page 2-2
        Page 2-3
        Page 2-4
        Page 2-5
        Page 2-6
        Page 2-7
        Page 2-8
        Page 2-9
        Page 2-10
        Page 3
    Screen analysis of chemical pulp
        Page 4
        Page 4-1
        Page 4-2
        Page 4-3
        Page 4-4
        Page 5
    Studies on the screening procedure
        Page 6
        Page 6-1
        Page 6-2
        Page 6-3
        Page 6-4
        Page 7
    Methods of using screen analysis data
        Page 8
        Page 8-1
        Page 8-2
        Page 8-3
        Page 8-4
        Page 9
        Page 10
    Literature cited
        Page 11
        Page 12
Full Text



SCREEN ANALYSIS AS AN AID IN

IIIP LVAIUATION
itohcd Ncvcmnlbr 19l9



SUNLiVSL IT OF \LORi A

UNIVESITY OF FLORIDA




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UNITED STATES DEPARTMENT OF AGRICULTURE
FOREST SERVICE
FOREST PRODUCTS LABORATORY
Madison, Wisconsin
In Cooperation with the University of Wisconsinr









C''. " A LYeI A.ID iI 1i ........

A rsum' of work at th.e Forest P-rodcts oLa ori cryr


*y

Z. S l * 3 : r AI-"






Th~is article suprc,.aes a publication c. the s';;/ tih" t I end
beings to- .. r r;.;se lts of several ind7p-:nd nt inv" sti c, s.i L;c:' ci
which u.'v not b n _1r ,viosly, report, d. T: Lacratcy :'irs cL ,. ix-
tcrest cd it. th- fi'nctior-aticno fic-'r :n ;ss,- r into n 2.r c]:iss' q. a'
.eansa of pC.p !V'_,!Itior. in a study of inrilntinf bo,-rd frcd:. :.nol.ii
wast7 '2 fr-c norrticn was ,fi ct d ;t.iL ;.xp ri::rx.',* f < -t
diaphnrr-. crr. r, cvid-d with n s'-ris cf int-rchx,.f .ai 1 X:ctt' d plates
of the typ crdi:;rily us:d in pulp mill scr_ nin.- c ratlcns. TiiI
apparatus ,as Inadr fi.oai'id 4'cr ippl icatic_. tc v 1. Pt inr 'C J:.c dwccd
and che-icl pulps by s- titting wii-, rr- rns f cr sLot d pc t .;.
ther st 72y brozouht ir:.prov-.d efficiency throuryh the d-v.Icr_ n., cf a
tip plat .'.. r-.n in which the sttoc< low..d thrc,<.' four co.Tpart..:
each fittecd vwih a scr, -nr. of differ-rnt siz' cp nin:s.

]xp' ri board pilps, *i.-. idw.ccd plJps, and ch-.,:.ic", p wlps wit '. l tiC sin'2. 2 e d
rr.ltipl diaphrarr, platy :cr, n: as w,-l s iiit-d n. c: nL of wor. .-ithI
the ta'i.'r-lcn r Cc 1 o % 0 if iC ir.



'.... Yd = lI CF l ..... x. h;, S. ....



,iin ; pl-' ,'r -n


-li plate use in h '; i:~l. -plat7 uj-. di>n *:*e :;r : n. e -f ; -
wre incn:c vid by .: inr.cs n^ ana ccnaa i:.. a e. c .:
inches l cr.E. -hr widths of th :ioc in ri- f IL. : :C *
O.*015 .2;O and~i . '^ irncn r'e)p, ctiv, ly. 1- ::. 1,t i" : e
h, +I"'. I *p i~ Cy
ratC ria a*i.n' thic.nh cr; v'a c- ir Ir' :. s x v;i'd *~


- 7Ac.no0,ed ,-:un is :r.id '. c tn-, App ton 2:.a i. >c:;.e: .. U-n, ..
for cocp ra ticn it. "n ,c:eii. ..- c it d s "::.d
for bjitin2. :i.oe in. *n vxic t. s of d v o ::. .. :I 1 .:.. 2.
is cor7L-rcial.iy .O n n as -h Appi.' c c' iv .. .


h: -'4






Fourdrini-r wire bottom. I.. sc-r e-n-plate- was then replaced by the next
larger in the series and the screening repeated. Th:e material daring each
screening was vigorously agitated on the screen with wate-r sprays. LOne
h-ndred grams of the original fiber required about 10 minutes screening on
each plate to effect a practical separation. Continued screening caused
th, various sized fractions to blend into each other, The various frac-
tions obtained in this way were then dried and weighed.

T.. screen analysis and other properties of three well-known com-
meLrcial insulating boards and one of an experimental Douglas fir board are
given in table 1. Th se boards are composed of various materials that have
been processed in different ways. It is, therefore, not surprising to
find no general relationship between the strength properties and the
scr-een analysis* Nevertheless, a change in the fibrous composition of
any one of them wo-ald undoubtedly influence not only the strength
properties bit its density, formation, insulating value, and appearance.
Having developed a product of satisfactory quality, the screen analysis,
therefore-, presents a means of control in manufacture. Plate 1 shows the
fiber aggregates obtained from insulating boards.


Th- Bauer-McNett Classifier


T-- ra-uer-ivc ..ett Classifier is a four compartment apparatus in which
the stock flows by gravity through a mesh wire screen from one compartment
to the next, :. screen plate is set vertical in the compartment and a
propeller agitates the stock suspension in a manner claim ed to orient the
fibers parallel to the screen surface. Ten grams of material are used in
each test. The fiber distribution of seven commercial insulating board
stocks as obtained on this classifier are given in table 2.


3CREN AhiALY,;I) OF ROhTjDWOJD PULP


3inc grouandwood pulp will practically all pass tnrough a plate
with -the isu-l 0.0Os-inch width slots, the separation of this type of
puip must be made with screens having openings smaller than those obtain-
-ble in the form of slots. For this purpose a series of screens con-
sisting of various mesh wire-s of the Tyler standard scr-en scale were
soldered to perforated brass plates. The screens were 24, 32, 42, and o0
mesh' of the Ty. r seri s which, respectiv- ]y hnve scr.en openings of
*{-, .r4 0.351>, end 0.24o mm. in width. ratio of the width of
screen opening in one sc'rrien to that of tri- next one in this se-ries is
approximately iqai to th- suare root of 2.

Th- procidcix or the single-ploat, scree n consiate d in using these
pats in ihi (ppiratus in the ord-r of their size, starting with the
s: ti ut. Th. fr!'c"'ion of then mat rial passing throug-h th screen was
c-ieuht in a, crate scr-; n the bottom of which was rrade up of a piic of








































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in 2013










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,;rh;.ct:ll c i:ul; ii _bo.rd made from Doaulas fir :a..:ii ,aste

(Single plate dia-,.r..., screen)


Di, ;.,.. :creen ana. l sis

Rietained btt-.;een


Saitaed -
: on :C


.020 and


incii
slots
c 1 n t


: clots: 2 lot1:. :

:Per- : Percent :

board A It 7
3or:=:.ercial board A : [(.i : i'6.7( '


a sro per. 0 Tt. I

"Passing.:T;,ick<-:men. [ty -:


.C.0.. ........... ... :through: no a.n
:l'.O15 and:U .O12 and: C.t :


: inci:
: slots

: Percent


Po and s


ticitv



Lb.Der


t;-e board!1

i:odulas of

': -..is- :R. ture

'treng-tx:


S:Lb. per :Ib.pcr
c q. in. .yq. in.


:(I) 7 1,0 :


'>1 ~o~ru B 3.~' 11.2


: 11.5 : 2 .1 : 6.4 :


. : 1.7 :(7)
:(A)


I .o :rciad board C :


-S.!c,,jrl:.tntal Dou fir borrd


1)-9


6c.l :


i.414 : iC'OLC


--.ii boards :,re brou:xt to .a :oistar uqaiiibri]L. rin an
an.d ifo F. irmediatuly bfor; t; ting.


atnmo.ere of 6) percent rl ative nu.i"ity


i-i i ty 1(x,(:cd in found. : r 1(A i;q. ft. o-^r i. .l inch tniclcnL;-'.
f In iCftuc fI; tj:.u n '.a.i.i :.ir.ctlon of tu. board;'I "Acro. s tni mnci.rinu direction of tcl hor "


36.6o :
36, 5oo:


374
3.3


3 5,


:(".cLu :()-Ui -


:Percent: Inch


1- ^
162J


: (i) 39,i(;'o:
:(A-) 3^,100o:


ic.6 :





























Retained on 0. .3 inch Pas:.in thr
with sos wi lt-3 ,o,


S. 0.15 inch Pa ri thr

t nd retained witi dlot
inch width slots on 8.QCS, in


'I ~








Tale 2. ---Fiber ;ize distribution of even cio .eriai insul.;tion ioardc took


:Cn li r:es: :Cn 2(
: (i. lie; m;.:. ) : (i./;


Ui Per : Percent : Percet : PerceLt :


P rcc:. t


:C,. v 4 ~ B~~::in<
.1 r he.


: e r ce te


i ( : ) :
(1)) :
Avera{:e.. :.
A ve, a; e


(t) :.*
CA)

Avera:e-. .:.

3 (a) :
(b) :
Av.\'ar" e .. ; .


(a) :


(h) :
.I'' r' \ )



#(b) )



(t) :


9l.7



3.7


9,.77

*t7. 3


59. (
55K'







C
'-r .0
FA .


.-
57. 9


i. . . . . .
/ ) "i '
SD J :. . . . . .
. . .


11J. c3



Ic. .

i

^*t
16.


T. j

S. )
-1.


* II.
* '-.5


B (


~L
S3.7





? ;",. "I!


2(,. 'r'
:?. c.



Ib. 1
179
I.7


.rit.


i 1. j
1(. .


Sl(.C : (. <


merlu}; :Cn P^- ne :rn S:,ecn :('r 0'' i~-)


:.L.. ) : I(, .. ?c -'r..


* 1' '{'













* i i .)
: f' C
. . . .. . . .



. . . . . .
. .. . . . .



. . . . . . .
. . . . . . .



: .]


. . . . . . .
. . . . . . .


)j :u~.) 0 nn.) u.-.17 r









Table 3.--Fiber size distribution of the various screen fractions of
Sr. _ni'.. c :d 1F p


Fiber length
rini i-


m Passing oc
: rcesh screen


Re tainted
between


he tainted
be- t -n


: :42 and o0 mesh:32 o:.d
: : screens : scr

Fr-m : To : Fibers : Fibers :
: : measured : reasurted : : :


mrm. : m=.


: }:'.r.bcr:P '>rcnt: Xihmber: Perc:: __um


-t2 i:.ishi24 and j2 mesh
*n C cr rn!;

rs : Fib -rs
r *d r: r oasi^r -e

S- '"'nt ;i :i. be r: F rce nt


489
15 9
7S


4

7
I
1
*


5.70
S18,70
S10.50
1. 92
1 I.C7
.54
.54
S .15
.15
*


~* 9* *99.9~ *999C~


2
19
41
37
54
49
53
72
28
35
22
13


0
0. 073
. 147
.220
.2c54
.36
.440
.515
.588
.6o2
736
.810


1.030
1.102
1.175
1.:
1.322
1.3S?'
1.470
1.545)
1.618F
l.o91
i. 75
1.837
1.512
2.G"')
2. "u
2.115
2.2r)5
2.375
2-.375


0.40
3.76
8.12
7.33
10.70
9.70

10,50
14.20
5.52
6.52
4.3
2.58
3.76 :
3.97
1.38
1.78
2.18
.595
.59
.59
.20
59

.20
-5;
.40
. ...


. ._


53






42
8
9





2i
11

10




11
22
4o
21
34
42
20
17
10
11
25
12
10
S
5
5
2



1
I


.. 073
t 47
2 L C





2

.736
.810

95b
1. 03 0
1. 102
1.175
1.250
1.322
1.39S
1.47C
1.545
l.o18
1.6,l
1.765
1.835
1.912
I. ,'.
2.6o0
2.115
2.2c(5
2.3F2
2. 375
2.43C


: 11
:75


5

C.
^J








:'1
9
ll
"7
4.
2




.
)

; 1









> r e /(


1


'2"
19
,17



cC2


02
.52
.()


.75
.35


.13
.o5


.74
2
.03

.74
.1.

.37
.^5


.2(
.27





* e


*9


9.

* 9


1
-7
1
7
S
-3

15
13

17


17
11


27
20
15


211
4
13
2u
11



I
J



3
4
10


1

l'_
3
3


2 .07)
: 2.05
: 2o35
: .88
2.63
4.38
3.80
2.92
1.4o


S4.57


3 .
4.00
;4.97








7-'
3.80
; 7.90





L' 2



: i-.1
S7.2



: 2.L3

i. o
1 .17

: 1.17{
: .29
< '
8?
: ..g

* C)
2 i-) OiL.
: l-') rrr


.1I : CV


Total.......: 745 : i5( : 55 :


. .1
: ". * *e. "9*e. 15
. ".. ..........: 7

. ........... . 3

..3~ie~
. . l........ ....... . 3
.: .. .;. . . : 3
. ...: 0
; 9. :. 1
:


. : i
: ...... ....... ].

*. ........9..lee~ .

............e ee*
*


: Above 0.oo2 :Abov-
3 : 0.45 ;


]. 7) rr1n.: Aboyv
: :).2C 4


bc tai, t d
t -,,e en
































































































* a.







tbriZ Out.-m ti : ; :i *' .:; ;'. .. c -**:;. C...:.ir *; :*. "o '": r-.







n:, 1.. c O r i I : 1 c a
<"^ is T.' > o .! rric r',' t i""'ir. 7 r. -'-',,*'^ o' 0 1 '. '. ''^- i ,i r.< -' t '-
':' P.s r -,c 1n- i r:,' .


* c :'


'* C 0' -


ir :? Cx.


t 70 ', r7'' **" '' o CO 2 c ... :,'c 1 "i r': Cro 7700' 1 0. 1 ." ... '' V. "'.i S ...
f:ac tl or.ati .nd f r i' r .a 'm-, t rp O 0:. frc i r.. ..'' T '. o ''
S'^ Ct o r:r" i'' 'z r. a3-- r',:-' nt a : "* q. ,-:v- : or. rncr- iof ,";--:* ,rac ., ,c or ,' 'iir i.' ro:


v -, o5 1. nN n:": :1. : F o S r 7. 7' I" z :; 1.,c:'. :
nO .V } ma -r ,- !-SLZ F. T .. ~ : : ,.. :O Z : :. .-" "g "" ..


about tr "n r ' Cor c' r',''-, T, I s'c 'a I
r' .7, o f i ..,. '7 a .+ a > 0 n;t. a
lyoji'~ c rv ,'':-. or 'ci' {r .. .. ,--, n r > !o. ..._717 7 C '7 717 n rf .' N

t 'a* ov,'rC "' : r l' r171' -. t,. :. C,'N-, r:':': : 0f ,'s 2r' :.7" s *a:'-T
T'" la' : ior: Of tr." rt,'rc''n* nv of .. ... of a .-iv-'r. *'*!',.-'>, t ";a

r.txt r i.' .' r or" 0 o"' l r .,t ;a \" ry ? .*ri ",'O" r7 r

ia'."n O'h '" p ";,'0' r r-'.^ r a ." ."- r cf + ta'
I s:1 *rib't 1o C of '.," f", r : 7 7.'* .' ..a..'r
"7"0 : .... 4 li S O0c) + i r," 2 :" " : ." S L P : :.

i;'/Lc,"~ ~ ~ ~~r n.o n{ + c c''c o" '' '"C-",: '' i e



:.ta ~ ~~ ~~ +': L ,N s: ." : ::::: :P' :- fO


0: ] :7, *.




0/ "

7, SC' :
"C" ''0 :


": ''';"C- 1" '0 1,f7'o0 01



*~cti r % :'q -. % :"-


S f ;r' 0. + '."


''fr c' 1 .


N ,a ..


: f c -f*' ; :.' o "


of n:,: fib- rr. int o ,*ro0..r' r cco "0 7,}- ; r z, "i)


' ,,- **- *" c r






Tho abscissas of the points on the curves shown in figure 3 are
rlotted as the midpoints of the range of length chosen. In srit- of the
efforts to insure a complete separation of the fibers tnere is a consider-
able overlaroing of sizes in every fraction. This does not, however,
invalidate the usefulness of the method. In commercial work the series of
screens needed will depend on the characteristics of the rulr and the
degree of separation desired. In some cases a sharp separation into fiber
classes may not be necessary. If a sharp separation is desired, a stud-
such as described above, although reouirirn.- a large amount of careful work,
'7ill be needed to determine the number and mesh of the screens required.

Detailed studies of the physical and chemical properties of the
screen fractions of groundwood pulp have been presented in other rublica-
tions (4,5). These investigations have indicated some very definite re-
lationships between fiber size distribution and pulp properties.


SCREEN ANALYSIS OF CIK.,TCAL PULP


The screen analysis has been found useful in studies of the effect
of beating, Trtin beating a mixture of spruce and birch sulfite rulps for
glassinp stock, samples were taken from the beater at intervals and
development of hydration and strength of the rulp followed by means of
the freeness and strength tests. The cutting action of the beater roll
,7as followed by the screen analysis, in this case with the single-piate
screen. The results of the analysis are sho-'n in figure 4.

It may be noted that the cutting action of the roll, which was of
stone was rapid during the first 120 minutes. Cutting was less rapid Aur-
ing the next 80 minutes but increased again during the last period of 40
minutes. It may be noted further that an increase in the amount of
material that would 'ass the 6C-mesh screen was accompanied rith an
approximately en ual decrease in the amount retained on the 24-mesh
screen. Tne intermediate fractions remained Tractically constant in
amount throughout. This example is cited to illustrate a u.se the screen
analysis may serve in determining what is nacr.ening to rulp in processing.

Another example of the aid of the screen analysis in the r.rocess-
ing- of pulp is shown by the data in table 5. This was a study of the
production of bond parer from bleached sulfite pulr. The screening was
done on the four-compartment screen sho,"n in figure 5. The analysis
indicates the trend of the processing effect on fiber distribution.
The porcentage of fiber retained on the 24-mesh screen was reduced
proportionately as mucn by beating as by jordaning although the beating
treatm,-nt ',as very mild. The effect of beating on increase of the
amount of material passing 115-mesh screen was nearly twice as great as
the effect of jordaning the beaten pulp. Generally speaking more than
tw'o-thirrs of tne fiber size reduction of the "on 24-mesh" material by
hating arpreared as increase in the amount of "throu -h ll5-mesn" material
wreraes only a little more than one-third of the size reduction of "24-
m ( material" by jordaning the beaten stock appeared as fine material.


58?4











__ ___ __ _ ___ __ __ _I i _ __ __ _
SI I - __ __ -
I __i

.~- Auction or: A.e.~ :'.c Z Z
I' o.vcar' ..i >. : r~ _
.L .{. i I5 .. xio: rc r
___I 0- ra*o r t 1ca r;.* ^ : ; *1 anI ")I ::- -: r e

I -
I i 1 -



* I -


____-__ __ __ ______ ____ _
' !
, >*. i .I .. I ..... ___ _......


V
NI V


-~ 5


' I


)-- v -- I II
- T:. u-Nv .:, -____ _______-____
^ o t - -- < ^ ^ 'V ^ -*^ ;, f I -' *. ~-^ i ) '


w iDc" i?'


~- '~
'1


I _______


h













' 1\ \ *" -si'( T ~ o .-; e '. s r e
I II
^ i ^'K /
,t ------X I ....^ ....
-, I_....._ ......___ _ _._.... ____ .'I

- 1 '"- ,. ,~~i
I- 7 ^ .
. .1iI .. .! I

i ) -i I I I
I" I i 1 _ I ;

, I I [ 1 { I i
t : iI _
SI -I
I 't -' /
-, 7 ~- iv - .... .
A i t- - -!








- 'K nl.--oca' ~ninalysis of -bnd.t n -n,-jdi.. dobl. t2:J


Processing:
treatmennt


: Retained : Rcteincd betw n
S on : .--------------------------
S24-mosh : 24 and t 42'and : 30 and
: 42-mesh : "8C-ncsh :ll'-insh

: Percent : P? rct:nt : P Jrc nt: Pt.rc'-nt


75.0 : .4


S 4.3


Unbeaten.

Aft r beating ...:

Aft r j0rdanivnE..:


: P1ssin. *
-: iiJ-.cs.





10.
i *) n
P -i r e t .
S I27 ."1

Y -


It v;a, also* observw.d in this inv sti. 'tion th-t t1i. .rc i t' ,.
fin, mat ri-.] in t.e IfurniL;h ,.'as assocint-d c.ith tLr ferocity of tii.
finislied T. r. Tnr a'tta in table o siiov tr't a iihr porosity v,.lu,
(morc densely zhalut) w.as obta in.d with iurniszhs cont-inirI -. xi i-h ,r
proportions of fin.-s.


Tab1 co.--Influnc-; of amount ol fines in thit furnish or. tj 9)orofi'.y
of sulfitu bond pnp,.r


*Machine : Proportion cf furnish :'Porosity of sn ,>t
run : passing 1-ifs. by Larl y
- ------------------------------------: d otr
SAft-. r jordcning : At hi,.d box :
--------------------------------------------------
S.P, r nt P. nr t -. -condns


1257
127?
12-,
12o7
1259


* 0 a ....... .. .. .. .....

. . ........ .. .. .. .. .....


: 1>.2


3C.O
5-'.3


145


5F.4 : 1c.1 .5 : b35.2

45.0 : 14.o : 10.0 .: 4.0


J:-. -' 1






STUDIES ON THE SCRLTiIINi' PFICEDJUREE


In the original screen analysis test employing a single-plate
diaphragm screen it was necessary to interchange screenr plates for each
f-ract-ion. This apparatus was improved upon by building four diaphragm
screens into one machine. In the improved machine each compartment con-
tains a: screen plate with different size of openings than the other three.
The screen is shown in figure 5. In operation, from 50 to 100 grams of
the pulp (depending on the fiber size distribution of the sample), in a
dilute suspension, flows by gravity from one compartment to the next
through the series of screen plates, the openings 1in t'the plate in each
successive compartment being smaller than in the one preceding. As with
the single-plate screen; mesh wires of the Tyler series have been used,
but with the introduction of one or two screens of finer mesh to the
series. The fibers under the action of the.vibrating diaphragms and
agitating water sprays in each compartment, pass through the screens
until they arrive on one, the openings of which are too small to allow
their passage. The fibers retained in each compartment at the end of the
screening are washed out, filtered, dried, and weighed.

Analyses of several commercial groundwood pulps and one experimental
groundwood pulp were made on both screens in order to compare the results
of the multiple-plate and the single-plate screens. The results shown in
table 7 indicate that the two screens are not comparaule except perhaps
in the amount passing the 60-mesh wire.

The effect of the amount of pulp used in the test is shown in the
analysis of pulp G-21 (table 7). The analyses obtained by the two screens
are more comparable with 50 grams of pulp than when greater amounts are
used. In general varying the amount of pulp causes greater variations in
the results from the single-plate screen than from the four plate screen.
This is shown in table 8. The variability is greater iii the four-plate
screen for the "'on 24-mesh" and passing "160-msh" but is less for the
intermediate fractions.


R8g4


f
)-0-





Table -[.--Co:.parison of cr:: n analysky s rcadd ;it- .......-a..
the four-platE fractionatin+g scrns

: .
Sample-: Screen : Amount :Letained: Rdtainet batint-<:;a :rP'-;;ij;
: taken for: on -.... ...---
: :analysis :24 mesh :24 and :j2 and ;42 and :
.... ~ ~~~2 I e s h : 4 2 m s ~ . .

" .Lber : : Gramr.s :Percent :Pcic ent: Percent:Percent: r c-nt

P 88 : Single plate : 100 : 19.0 ; 4. : 11.7 : 4. : .
Four plate : 100 : 24. .4 : 2.4 : 1.4 : .

P 895 : Single plate : 100 : 14.0 : 4.0 : .1 : 7 ;.
SFc-ir plate : 100 : 28.1 : .5 : 2.3 : : 2.

P 8 o Single plate : 100 : 12. : 8.2 .: 7.5 2 '8 .
: Four plate : 1O0 : 1. : .K : 5.3 : 8. : '.

P 957 : single plate : 100 : 27.4 : -.4 : 7.4 : 7o. : .
: Foar plate : it. : 28.7 : .5 : 4. : .2

P 501 : Iingle plate : I( : .0 : .3 b *. : 2 .
: Four plate : 100 : 18. : -.0 : 11.1 : *,.

P 502 : Single plate : 100 : 10.3 : 8.7 : 10.5 : 10.2 :2 .
: Four plate : 100 : 24.5 : J57 Uc :

G 21 : Single plate : 100 : )c.O : .3 : 5.8 : u.7 : .2
: Fear plate : 100 : 45.5 : 7.8 : 4.5 : -1. : 39.1

G 21 : 5insle plate : 72 : 57.b : 5.8 : Y.4 : 8'. : t
: Foucr plate : 75 : 47.7 : 11, : 9.0 : 1 .-r : 1.;

0 21 ; ,in e plate : 50 : 58.0 0 : 12.0 : >,.
Four plate : 50 : e.'5 : 1(.5 : 4.( : -3.' : J-.

-Co..;.ercial ~,roa.ndwood pulp indicated by "P", expri;:ental u'y "3".


v





























































* 4 4 4 4 4 *






* 4 4 4 4 4


* 4 4 4 4






4 4 4 4 4 4 4


- 4 4 4 4 4 4 4 4

















4 4 4 4


* 4 4 4 4 4 4





















4 4 4 V
















4 4 4 4 4 4







S. '1f


*ft S .


*


I


m..
. "
-It*" _,^s


y .. ...e


* N l H


"I


A


A


I F














Table S.--Compnrison of sin. in r..- rr to v ri ii iC rr ts c' :. v r.' *
amount of sample


Fr aict ion Vr iab i I i ty-

SSin-le rlate screen : For r,'t scrn

: P rcnt :
taintedt on h ..... : : 1.

HRptninfd b(t':- n: : n
4 d 32 s >n41
2 'n 4n i s ....d. :
42 fi d rcsh . 42 2 : l<. '*'


l b- livi dinr: te ar:' of
rby "(-p of 'll v'1 .li
of s-mp P -'r 2, rI, r0n1 of
(Sep ta'-,l, 7. )


ff,
it : r r i'* '*i'. r>:.O ; 1'0
'-ilr frO.T .-'* ir ''"'r r'lL ];O .


nbi ho'"'; n n :'bpr' of do i cl', !n' a.> ::', o t:. ''o0 -
r'lat cr .n rvick-dIat. r.'ndor; fro':.. la ,' i,'-'r p "of r- .' ; 'r. VI-;.dood
pulp. In" r ;i:t3 .' no- doic.': ilit to <. 'ood i'or '.... *, o"
It is n'r.ra7iz. 0o- v,, ".> '-* '>t.o 2. nroc r, o olo' i io
not diff icu it F7 not o:- to '. oo 'i''ion o
'ittcntion to 4o Tn 'i l :. iv' 1 t, i nxr' ri'nc r..... "'.o'n : *'
' n lvtic'i j'r cirior. c,:-o 'x .x t fro7 ; fz' o io :.on s l.. .
it is for oxi? r n ', .. .'.'
spm.1:,pl is t o c" r.r',f.'rr,-d t. 'I;:c s .... I .. ... t ">'k,. n s :'; ; ,u c<- ."'if "'!. "! .. .. ... ". *-- .'...
for tn' s-n'' i'? ':c ion obtain', 'o C,* *":.: d or. > .>c ..
: in...::. of or -nru r" t of s ,r:.. Ali t'':t: >:o l b r 0.
d .u T i i c r t ,. T h o, d --r - o f d u r l i c n i c -i l i t y t r: t ;;; n ,b- '. .x r,, r c o r b f o v-r r
corny rti. nt scr,',n of thr For, st iro'o -.ct.-, o* 0 ..."' or: i r'.n:i,:.'::*, iif-
fer', nc," of : in frr'tlons 'r..o n' ir.-: to ......' .'. or :.o0' of ;" ,
Smaxi r 1iff 'Crnc of in frr' ti ons j".nt n -o n "--n 1 4.d 4 '-
cnnt, inclf iv', in r u.xi lur f i'.r no, of i:f fr"c :onn '".:o- -..
to 1's3: th'n 1 r.r0 ofn t0 vno : 0 "In .


S?'?;4






IETH'ODS OF USII'G SCREEN ANALYSIS DATA


A screen analysis as ordinarily made gives from 2 to 5 values
depending on the number of screens used. These may be used for ccri.p.rison
with a similar analysis on a pulp chosen as a standard. The use of
several numbers for a test result is somewhat inconvenient and several
methods have been devised to make the data more useful. Discussion of
the relative merits of these methods follow.


Screen Analysis Curves


Screen analyses may be conveniently shown by curves. The plot
of the percentages of the various fractions against the widths of the
openings of the screens upon which they were retained is usually so
irregular that a smooth curve cannot be drawn through the points. How-
ever) if the cumulative percentages are plotted against the screen open-
ing a smooth curve may generally be drawn which rises continuously from
the amount retained on the coarsest screen opening to the amount retained
on a hypothetical screen having openings of zero widths. Since the
cumulative percentage is defined as the amount of material that would be
retained on a given screen if it were the only one used in the analyses,
the amount retained on the screen with openings of zero width is, of
course, 100 percent. This type of curve is, therefore, useful in
estimating the amounts of material that would be retained on screens
not used in the testing series.

Either Cartesian or semilogarithn coordinates may be used for
plotting the widths of the screen openings. Both have certain
advantages. Owing to a constant ratio between the widths of openings
in the Tyler screen series the ordinates representing them on the
uniform or arithmetical scale may become very close together as the
widths decrease, whereas on a logarithmic scale these ordinatesare not
so compressed and thus offer a more convenient method of plotting.
Since the logarithm of the screen opening equal to zero is infinity,
it is impossible to draw thu curve on semilogarithm coordinates b,;tween
the smallest screen opening used and screen with zero openings. Thus
it is impossible to estimate the amounts that might be retained on
screens smaller than that usud in the testing series when the plot
is made on semilogarithm coordinates. Figure b shows several typical
cI !.d-tive curves for groundwood pulp drawn on uniform or Cartesian
coordinates.

Screen analysis data shown in the form of curves ,rny only be
compared visually. However, certain properties of the curves may be
expressed nurw;rically and ised as a means of comparison. A discussion
of these factors follows.


R8 94


-g-







Table I .-- ei c f djl iK iLI i Icr "-c
four-plate fractionatin,


: R etainedd. :Rttaind b ;t.
oil 0 ------------
'4 mush :2 4 and 42 and .


: 42 :sh : 8 mesh

P recent : PFrctrnt : rrc r- t


c '~:w.
~ :..~- .i~

~ ire ii.;


IL





* Zi~ Li.


& 57 a
b

G 80 a
b

G 14-' a
b

C 217 a
b


C 312


P 993 a
b

P 1101 a
b

P 11S6 a


-Cc:.--r: racial


.3~onpI 1


Numb e r


1.0
1.4

0.0

7.2

7-K;
7. :
10.0 :

19.i, :


7.3 :
8.4 :


4.8 :
4.0 :


12.1
iL2.7


18.1


14.0 :
1i.4 :


2.1


4 .0
4.0


15.2
14.2

17.2
18.8

lg.
1-7.


1 1.3)
AL..4


iLo .4
14.5

20 0
20.0
k~ .c


2-1.3)






12.)
13.1
15 .o1




15.4
15.4
l3.b


12.1

I0 .l
1':.

lo 1


21.2


L) .4
23.0


15.4





2f .8

0.




1.4
lo '




14.8
19 .

Ii I

I1^1


)' .(


.1
"+1 *~t-


'-I- je

*1- .


t4 eQ
0

'-I. .9
4.

*-1. .~
9'1~


4.0
3-7


pulp ind~icat', d oy "P") *xpjrin ni by
































































































* 4 *































4 *















I ,.I // / !
I r ,


/
(I



II


I i I,
*t ; jI* / I


** > j 1













A r> ::o.,b ...,_ : ICO' q'::,. .'- :oI'O KZ' : q ,-" [
vio s u iic-ticn? (] ,, 7hlt f.ct:or is ".!>*C surf,> of t' 2




107'Lit coor a' 2?, ::*. ....i;i 0t- oo i,: :. C
Of %h1, CO't rs- x'.. :. : .q r, :2 9


bp c" Ic u.i t,' I.

incluj. in :'. :.!

of th "z' ^r-' of

a~t i n:, "vq a IF '


-:*.'" t follo :i7 r r0''i. ion as :. :


of o7I; C-.r7. l : '"v r,,:'c. r.1. ''. .. 3 'r'' r- 1 f:'c
of i~ o" '" o i


f I.. *7.. t ': of *h corf :' t' s . r7
for" a cr '''r. or r. ,:1. of ". ": :. n .. .. .

"b .'* n r r n n:


:. I C '",



" -. ,:-'


'~'0





2 1:








0>
C.


l--i + 4-. +


co0"ir 9 "F* :f n- : O s '-1 *. 3 :', "*; ':" * ^ ::

o r 0 0,, :L



n -0*7"1'7
... t I,-" 1 0:: O0if2or:: Coor C:1. '

1 r.'1 th-'' r'r'OT O:'t Lor. Ot* :2. S:.O "*


S~tiq' on, 0c r iset ri- :.o':: '- v
sC :p. r o "- : .- scr^ r- '. -l" ': :*

in th-, '^r,.- ;..nd* r th cujrv" or"
1 ul'0 r
in'r r o-,v- o


A .." c fo;n:
thit.:u of :hc r-lr now
[:ulr"::_). it is 'ro:'

to th" "flb,r i.'r' t}h
indrx mr<> bc d,0 fi2,0!
fair of sotr0' ns" of" v::"


(U


;o o: ^ : or. o ..o :: *


70' 0 -0 O" (5' *0 : "


C-.. .


. ;o ;


o r ')
b 1


*: '\'* r'' CI " 7% W f.1' 0" :
>r:' v> i. i -. ,rx~t :i :'. o',


'c~c,"-ic
0 2
0 .7


Sc r-,, **n 1r"l 7_:,xrts 'i'i r l .>~L 1 .'.'*'^


- :" 4,











length to -oass and the other just -permit fiberr, of average !en.tn to
be retained. It is calculated from screen analysis data by, assujin,?
tnat tne summation of fiber lennTt2ls per unit weignit of *ouln is a con-
stant and tnat them number of fibers in a unit 'veieht of a -:iven frac-
tion relative to tne number in another fraction is i- inverse ratio
to the '-idths of the screen openin,:s. Table 10 illuscratcs one method
of calculation.


T-b C 1 C.--1,utthod of calculation the fiber-lemnth index of a. )ulp from
the screen analysis



Ranne of screen :Average : Factor :Relative :Relative : Relative
------------------: of for :T:eiht of: number total
Sesh- : ".idtns of : -,idths :relative : oIlp : of : length
: oening : of :m.umber of: retained: fibers : of
S:openings: fibers : between : : fibers
: : screens :

S: A : B : : -: A_-D

: n. : : Perc nt

1o- 24: 0.9` i-0.701: 0.84o : 1.00 : 1.3 : 12.3 : 1.4

24- 42: 701- .-l: .526 : 1.61 : 2.7 : 4.3 2.3

42- 7(: .35)l- .175: .263 : 3.22 : 20.0 : 64.L : 16.9

80-150: .175- .104: .139 : 6.09 : 63.0 : 3S4. : .5.

15 0 : .1t4- .0 : .052 : 10.30 : 2.0 : : 1.7
Total ..................... : 00 : 4' 4 .

Fiber-lengtn index of the pule. .u ./497.6 e 0170 rim.

-TyI er standard. -ne 16-mesh screen represents, in this c.se, the
sm,'lle st mesh tnroui-h v''nicn all of the culP) "ill pas)'.
2It will be noted tha)t for a -iv n st of scr,, ns tnr summ-tion of
A)D 1'ill be a constant eou1l to 100 times tna pver ,'-.-e of -idthns
of openin-'-s of tie t,"o coarsest screens.


a?, 74


-1l -







(.1) Cchafer, :E.. and Crtrpenter, 1.A. cr Al i n Aid ir-
Pulp ovaIluaftion. Pap r Trade J. e-C, N-. 1';,

(2) 3chafer, .ik. and Car'penter, L.A. "Groundv.', I ilp -vi '.ticn Ly
ea,'ns of Static -~nding Screen An'dy.i: ia cf FI.* :,: -- :.
Thch. A:oc. Paipeis 15,(1):2C7 Gjvy 1'J) p-'r x-'d.. .
Mo. 3, ol (July 17, 1 30).

(3) 3chafcr, E.R. .nd Hiir.i, .ciburn. Frt r i o. rc d
Pulp ']valua-tion." T ech. A:.cc. P;pes 14, 1, '..y 1^3i). P r
:* de J. (-3, No. IC, S( pt. 3 1^1)

(4) ohu> r, .I. 1 tai a, .tti. "Enff1 t cf r- n .iz i
Fib( rI, cL ti; PLhy.;1ic:-l Proprti(s of Groundvood *. lip." 'c..
Arc P r: _L (i) :L~44 (Ju l)j4) P-p Trud- J. ,7, >c. i-
4C .. [lv ', .3 ).

(5) -chaf`ri, E.R. ,nd (A*ntahoLma, .utti. "Oh ic I Prei rti; of I> r.
Fractions cf 5lacK Gx;u: :'nd 31'.-h Pin,- Gr ocd I Jps. ich.
As cc. Pp ir: 1J (l);3i (Ju 13). Pap' 'Ir; . M.
40c (N\,o v. 13)


-I1--


Rgg4




UNIVERSITY OF FLORIDA


3 1262 08928 5869