Draeger Report of the Committee

8/10/2019 Draeger Report of the Committee

1/5

23

Report of

the Committee

on Sampling

Cane

for Sucrose

Tests

U l I J ~

Committee: P L DRAEGER G BOOTH G. S. MOBERLY

Convenor .

Bein.

a Sub,Committee the Committee on Standardization Chemical Control

/

Mr.

Moberly

read th e following p a p e r : -

GENERAL CONSIDERATIONS.

In order to f ac il it at e

and exp ed it e

th e

taking

of

i nd ivi du al s am pl es it is

necessary

that

t he l ay ou t

of

th e

mill yard

an d

th e

unloading

devices sh ou ld be

designed

with

this

end in view.

is r ea li se d that

it is not fe as ib le c om pl et el y to

re-design

th e mill

yard etc. in existing mills

bu t

certain recommenda

tions ar e made

for guidance

in making future

changes.

EXTENT OF S AM PL E.

Since it is

imperative

that e ac h s am pl e s ho ul d be

as representative as possible of each consignment

it is

recommended that

a sample be no t less than

750/0

of

t he w ei gh t

of

any con si gn ment

on

anyone

day an d should be no t less than 10

tons

of cane.

UNLOADING

DEVICES.

It is recommended

that

where

there

ar e more

than on e

carrier

each should be

served

by a

separate unloading device so that on each carrier

there shall be no danger of

mixing

cane from

different

consignments.

Where S.A.R.

and

narrow gauge trucks are

un-

loa ded on to th e

same

carrier th e

unloading

devices

should be adequate to deal with eithe r type of

truck

separately.

CAN E T RU CK S.

Wherever

possible

narrow

gauge cane trucks

should

have

a c overed bottom to

assist

th e rapid

unloading

of the last

portions

of cane

an d

fo r th e

same reason the grabs should be so

designed

that

they

can

pick up cane

lying

in th e

corners

of th e

trucks.

SLINGS.

Th e use of slings greatly facilitates th e handling

of cane especially where this arrives

at

th e mill in

wagons.

WEIGHBRIDGES.

It is

recommended

that at

each

mill th e weigh-

bridge should be placed as near as possible to th e

carrier for th e following r eas ons ; -

1. To assist in th e marshalling of

trucks

into

samples before

weighing.

2. To reduce

th e t im e d ur in g w hi ch ch an ges

in

th e w ei ght of cane ma y be

brought

about by

evaporation

or

rain.

3. To

reduce

the am ount of cane be tw ee n the

w ei gh br id ge a nd

carrier at th e en d

of th e

crushing period.

This

change

would

necessitate a larger weighing

staff as w ei gh in g w ou ld have to be continuous

during

crushing

there being no reserve of

weighed

c ane on ha nd .

AUXILIARY CARRIERS.

While th e use of

auxiliary

carriers is a great ai d

to

sampling

is

felt

that

this

would

be a

retrograde

s te p f rom

an engineering point of vie w

an d

is no t

to be

recommended.

IDENTIFICATION

OF S AM PL ES .

T he C om mi tt ee is of opinion that a uniform

method

of

identifying

samples

a nd c he ck in g

their

correspondence

with weight

an d

tests is necessary.

The

following sche me is suggested.

Th e

weigh

b ri dg e check er

should hang on the fr ont truck of

each consignment a ti n disk on which he would

chalk th e

name

of th e planter

an d

th e

number

of

trucks in the consignment. The

cane

tester

on

duty

should keep a

n ot e b oo k

in

which

to

e nt er t he

planter s names number of t ru ck s a nd t he n um be r

of th e first a nd l as t

truck

in each consignment. He

s ho ul d also enter th e

time

of c ru sh in g a nd th e

percentage of th e sample crushed. Th e bucket in

which

th e juice sa mpl e is collected should have a

dab of black paint on it on which s ho ul d be c ha lk ed

t he n am e of th e planter. The t es t jar in which th e

sample is placed should be marked by

means

of

ti n

label b ea ri ng t he p lan ter s n ame which couldbe

hung

on th e lip of

th e

jar.

W hen n ot

in use those

labels could be hung on a board on th e wall in

alphabetical order so that t he y a re easily accessible.

In t h e w ei gh brid ge a

book

s ho ul d be

kept

showing

th e time

of

arrival

of each

truck

a nd the nu mbe r

of

each

truck

in every consignment and its

weight.


2/5

This

book should be sent

over

to

th e

laboratory

periodically so that th e chemist may enter the

weight against each test. In this wa y every sample

can be identified

a nd c re di te d

with its

true

weight

an d

test and a

record

kept of th e

time

of

arrival

and time of crushing an d

t he p ercent ag e

crushed.

SAMPLING

OF

TH E

CRUSHER

JUICE.

A

form

of juice

sampler

is

at present being

in-

stalled

at

certain mills on the N orth

Coast

which

seems very suitable

for

th e purpose.

ro w

of

small holes

ar e

drilled

right

across th e

breadth

of

th e juice

chute unde r

th e carrier.

Beneath

the

c hut e and below these holes is a triangular chute

leading

into a trough

which

in

turn

leads hack

under

the

crusher so

that

th e excess of juice rejoins

24

the rest of th e expressed juice. In this

latter

trough is a small hole into which can be screwed a

tapered

bolt which allows for an

adjustment

of

th e

quantity of juice which

ca n

escape from

th e

hole.

Tw o of

these

holes

with

adjusting screws can be

placed in th e

trough one for th e planter s sample

an d

one for

th e

mill sample.

These

holes can easily

be cleared if

they

become stopped by

screwing

out

t he ta pe re d

bolt and then

screwing

it back to it s

former

position.

CONCLUSION.

While th e above

cannot

be considered to be th e

final word in sampl ing these r ecommendations

should go

fa r

towards simplifying

this

difficult

work.

Juice plate

Holes

End elevat ion

chute

Details

of adjustable

hole in juice chute

Juice plate

Holes

Side elevation

RECOMMENDED CRUSHER JUICE S MPLER

Chairman

: You will recollect

this Committee

w as o nl y f or me d in January so

that

there has been

very little

time

for it to

ge t

to

work.

Th e

sampling

of cane is a

matter

of

great importance

especially

in view of

th e s ys te m r ec en tl y a do pt ed

of paying

fo r cane on sucrose content.

Dr . Hedley: There is one

point

with regard

to

th e

recommendation

of

no t

less

than ten tons

of

;

cane sampled. Quite a

lo t

of planters send in only

a bo ut t hr ee

tons

at a

tim e a nd

it would

mean that

they could no t ge t samples if

that

recommendation

w as carr ied

out. There is also

t he a ct ua l

sampling.

I d on t k no w whether it would be possible to fit

th e

chute

recommended to all mills. I think it would

be

rather

awkwardto fit t hi s c hu te at Felixton. I

think

much more consideration should be given as

to how you a re g oi ng to

get

an adequate sample.


3/5

Chairman:

Do you

think

it would be practicable

to have

th e

device of

t he t ap er ed b ol t?

.Dr. Hedley: That is in th e

return

chute.

Mr.. Watson: This scheme is already in position

at ou r

Darnall

factory. I don t know how it is

going

to

w or k b ut

it seems to me to be

quite

a

feasible thing. With t he t ap er ed

bolt

it will only

need a little adjustment to arrive at what is required

to ge t a full sample. I might

say

it is a Fulton

crusher

of

the same type

as at Felixton.

, Mr.

Moberly:

With

reference

to sampling only

three

tons, of course, that

recommendation

would

have to be modified. As Mr. Watson savs

this

scheme is in use at

Darnall

an d that is

where

I go t

it from. It

struck

me as

b ei ng q ui te a de qu at e

for

th e purpose. Th e idea of the tap er ed bolt is that

you ca n so regulate th e flow in that

return

chute,

that your bucket

ca n

be filled up in

th e

time

required. W it h r eg ar d to returning th e juice

back

under

th e crusher , if there is

an y

difficulty in th e

particular lay-out

it might be returned into

th e

side

gutter.

It

does no t matter

ho w

it goes back.

There is an

almost

identical

sampler

at Empangeni

the

difference

being

that instead of t he r e tu r n

chute

w it h adj us tabl e

holes in it, th e juice flows into a

bucket at one side an d flows ou t

at

th e other. Th e

c om mitte e were n ot all certain

th at t ha t

really

wa s an average sample. We

thought

this method

in use at Darnall would

certainly

ma ke the sample

more representative.

Mr.

Bechard:

I wa s at

Felixton

la st year an d

wa s

in

charge

of

th e

sampling of

th e

cane so

fa r

as

the planters were

concerned. I

wa s

on

th e

co mmit tee w hen this design wa s considered an d I

think it is possible to

introduce

it at Felixton.

W it h r eg ar d to sampling 75 of th e cane, we

ar e

act uall y s ampl in g more

than that at

Felixton

Vve

ar e

sa mp li ng ov er ro

and th e

samplers a re

adjusted

so that we do

no t ge t

a

bigger

sample

than th e mill. As fa r as t he s am pl in g for sucrose

content was concerned we ha d just

th e

right

quantity.

On th e question of deliveries of less than

te n tons I

think

it is fully me t by th e Fahey

agree

ment;

we

ta ke a bout

-three

samples

f or pl an te rs

whose deliveries ar e small.

Mr. Dymond: I

asked

t he commit tee to go

into

th e

question of

sampling

as- we have it at

Empangeni.

Early in

th e

crop some

planters

complained

that ou r method

wa s

no t

to

their liking

because there w as l ar ge samples an d small samples.

I

illustrated

to them in a very simple wa y by means

of coloured juice, that provided you ha d an inlet

a nd o ut le t

at opposite ends of

th e

bucket

you

go t a

circulation of th e

new

liquid coming in, an d I sa ti s

fied them that a fai r sample

wa s

obtained. I myself

am no t absolutely satisfied that it is a

perfect

method

of

sampling bu t

it

wa s

the best

available

at th e time.

Chairman:

does no t

strike

one at first

sight

as being a

v ery s ati sfact ory s ampl in g arran gemen t .

However

if it

has

been

tried

with coloured juice

it shows it has some possibilities an d it might be

modified in some wa y to make it a satisfactory

method. On th e face of it I would prefer the

system outlined in t he rep ort.

Dr. Hedley: I think

this

tapered

bolt

business

is going to

necessitate

very strict a tte ntion to it.

I have no t seen

an y

small orifice which will no t

block unless

you

have some

continuous method

of

cleaning it. Yo u

know how

filthy th e cane is at

times. I

don t

feel that even this is going to be

th e

solution of

th e

juice sample problem.

Mr. Moberly:

is quite possible that this hole

is going to be choked up

bu t

it will be much more

easily cleaned than t he m et ho d at Felixton. With

this

it would only be

necessary

to sc rew the bolt

ou t an d screw

it

back

again. In

th e

same

.way a

ta p through which juice flows gets very filthy

inside. This can be kept

v er y m uc h

cleaner.

Chairman: That is

th e

only obvious object ion

that occurs to one,

th e

difficulty of

keeping

it

from

being choked.

Mr.

Pearce:

There has been some dispute about

th e

Java

ratio holding

after

rainfall.

W e a r e

talk

in g

about sampling cane at th e

crusher.

I have

heard

some

talk of taking it from th e firs t mill

juice. H as a ny th in g been done?

Chairman:

That is

going

to be discussed in

a

paper

which comes next on

th e

agenda.

Mr.

Pearce:

What is th e position about

taking

th e sample on t he crus her?

Chairman:

ma y

be that th e

method

will have

to be modified, bu t as it

stands

at present we ar e

under

th e obligation of devising

met ho ds for

satis

factory sampling of crusher juice.

might no t be

th e case in th e following season.

Mr.

Moberly:

There is t he f ur th er considera

tion

that

even

if we did evolve a

method

for

testing

cane without

th e

analysis of

t he c ru sh er

juice we

would still have to deal w it h c ru sh er juice, so that

would still have to be sampled.

Mr. Warner: With regard to the 75 ,

where

yo u have

cane

coming

in

with variable

fibre

content

yo u

c rush sa y 75 of one class of cane and then

75 of another class of cane going through th e

same openings of th e mill. I

sa y

that is a hindrance

in

t he e xt ra ct io n

an d in th e

capacity

of

th e

mill.

It might be theoretically

right

to obtain a correct

sample of th e juice of 75 bu t is it a practicable

proposition

for the

millers t ha t t ha t should be done?

m ay a ct

in

several

mills

where th e

canes

ar e very

much of th e same class,

but

where you come to a


4/5

mill that has varying fibre content and so on I think

it has

got

to do w it h t he e xt ra ct io n and capaci ty of

th e mill. As to th e weighbridge being as close as

possible to th e carr ie r, I quite a gr ee w it h t ha t bu t

that is a m at te r t ha t has been battling on for years

and it will never be accepted by th e planters. We

would welcome it as millers to have th e weigh

bridge

right

over th e

mill,

bu t

it would never be

accepted by the pla nters as they ma y send in cane

on Saturday and it may dry

ou t

before being

weighed and they will

no t

bear the

loss-but

we

must. We have always been in th e habit of putting

th e weighbridge further back on th e suggestion of

the planters.

Mr.

Bechard:

On the question of th e weigh

bridge th e point mentioned by Mr. Warner was

applicable before the system of payment on sucrose

content under t he F ah ey a gr ee me nt came

in ;

it is

true that when the

planter

wa s

being paid on th e

quantity of cane he

wa s

delivering

th e

b ig ge r t he

weight

th e

better

for him. I take it th e planters

ar e now going to realise

that th e

weighbridge

weights

after

all do no t matter so much. Th e weigh

bridge weight

at

present becomes a dis tr ibut ion

figure and the juice scales figures are the most

important

at

the moment. When the planters

realise

that

it is no t going to affect them I don t see

that

they will have an y objection to th e position of

the weighbridge.

Mr.

Moberly: With

regard to the sampling of

75 of cane in mills where you have different

types of cane, that is an admitted difficulty, hu t as

a

matter

of

fact

at

Felixton last

year

we managed

for a

great

many months to sample very nearly the

whole of each consignment

that

came in and kept

going. I admit

that

in another

year

it might be

different. Th e difference in fibre ma y be so

great

that it would be impossible to keep th e mill going

with fuel if you r un t hr ou gh a big cons ignment of

low fibre cane. In

that

case some effort would

have to be made to meet t he situation, perhaps by

dividing up the consignment into tw o portions,

crushing

at

different times, and

uniting

th e samples.

Bu t this difficulty does no t always arise as is shown

by

th e

fact

that

we

managed

to

c a rr yo n a t

Felixton

last

year.

Mr. Watson: In th e compar ison of fac tories

it is stated this season shows a decrease of 1.56 as

compared with 1926. Amatikulu is one of th e

factories

at

which the e xtrac tion wa s decreased by

1.5. I pu t down 50 of that as directly due to the

fact

that

we have to cr us h e ver y individual con

signment of cane by itself. You c annot set a milI to

tackle

sixty different classes of cane in a da y as we

have to do

at

Amatikulu. A fair

mixture

of cane

is

what

we have always

tried

to

get at th e

carrier

before

t he F ah ey a gr ee me nt

came into being at all.

t wa s ou r

special effort to

make

a proper mixture

of

th e

cane

at

th e carrier

to

make sur e

that

one

setting of

th e

mill would meet nearly alI require-

26

ments.

There

is

another

point

that

has

no t

been

mentioned and that is

th e

trouble in clarification

.when dealing with certain

consignments. \Ve will

ge t one coming in with a purity of 83 followed by

one of 93. You have your treatment of juice for 83

followed by 93. A g en er al m ix tu re of th e juice

would make clarif ication much easier than dealing

with

wide

extremes

as we have to

at

our

mill.

Mr. Moberly: These discrepancies ar e ones

which I quite appreciate, bu t if you do

no t

sample

the greater portion of a man s cane he is no t going

to be satisfied in cases where rejections occur.

it were no t a matter of rejection the point would no t

be so serious because it ma y be possible to convince

some of them at an y

rate

t hat in the long run th e

differences would average out.

Bu t

whe re the re is

a

danger

of small portions of his cane being

tested

and the whole consignment rejected on that test

nothing

will ever convince him

that

he is getting a

fair deal,

an d

he has always

th e thought at

the

back

of his mind that

t he u nt es te d p or ti on

is very much

better

than

th e

other. Admit tedly it ma y be worse,

but

human

nature

being

what

it is, e ve ry planter

who had a rejection on 50 sample would be con

vinced that th e o th er 50 would be the best cane

ever sent in

that

year. That is what was at th e

back of ou r minds when making this figure 75 .

That is the lowest figure which t he p la nt er s t he m

selves have decided they could accept.

Mr. Bechard: I quite agree that it is very

difficult to handle cane that is continuously varying

in composition, bu t on the other hand probably the

use of

Dorr

s clarifiers would neutral ise

that

to a

large extent.

It

is a question which ought to be

inquired into by the committee on clarification.

Mr. Booth: When I was called on this com

mittee, and I wanted to find ou t

what

was th e

actual percentage of cane sampled for the last year,

Mr. Moberly told me about 90 . I

thought

in view

of my own work

at

Umfolozi

that

this was a very

high figure and I had in mind the

argument

that

Mr.

Warner

has brought up, th e effect on clarifica

tion in dealing with such large

quantities

of flats.

cane. I have had considerable experience of

Australian

practice

an d th e

conditions

there

distinctly laid down that 30 of th e cane must be

sampled. I found

that

was

no t

sufficient for Natal

cane as the variations in sucrose c on te nt w er e so

great. A

te n

to n sample has been advocated as a

minimum because I cannot see that anything less

that te n tons constitutes a sample

at

all. In order

to protect Mr. Moberly in the various troubles he

has, and reduce th e friction with his planters, the

idea of fixing it

at

75 was taken so

that

th e

planters would be

sure

of a square deal. they

could

get

90 so much the bette r. I do

think that

Mr. Moberly s organisation should be

protected

by

allowing him to say 60 to 75 as a sample.

Mr. Watson: I can also sympathise with Mr.


5/5

Moberly in his difficulty. My opinion of

the

method

is that it is tending to inefficiency in. mill work.

Surely

that

is to be avoided.

t

is actually

putting

a premium on inefficiency. A mill cannot be

efficient if you

are going

to crush every sample by

itself.

Nor

can clarification be efficient if you

are

going

to clarify every individual juice.

Mr.

Booth:

Mr. Fahey will be

here next

week.

I realise that this

matter

is likely to be a source of

friction between

the planters

and millers. I

think

this Association might put it to Mr. Fahey that he

should go into

the

matter with

parties

from

both

sides and fix what should be the percentage of cane

to be sampled.

Mr. Warner: I would. not like it to go as a

recommendation from this meeting that 75 should

be sampled.

Chairman : It is a recommendation from

the

sub-committee

that

was appointed from

the

s tandardisat ion of chemical control. I

understand

the Chemical Control Committee will have to deal

with it. They have not had

time

to receive and

consider this

report

as yet,

but

it will come up

before

them

for discussion before any final decision

is made.

Mr.

Dymond:

Does Mr. Warner refer to flat

cane or to hilly cane when he speaks of 75 .

Mr. Watson: I have had very little experience

of flats cane.

Our

cane at

Amatikulu

is all hill cane

ye t

we

get

up to sixty different consignments of

cane in one day.

Mr. Dymond: I asked this ques tion because my

experience is

just the

reverse. The

crushing rate

is dependent upon the tons of fibre per hour.

cane of low fibre is crushed,

your

crushing

rate

automatically rises. This is nothing new and can

be substantiated. Regarding the effect on the

extraction I cannot believe that a 75 sample is

going to

make

any difference. t is not as though

all

the

cane for

the

day could be

thoroughly

mixed

and an average cane of a definite average fibre

obtained. No,

the

mixing of cane ment ioned con-

sists of the offloading of bundles from two or three

consignments at the same time. This is not mixing

cane bu t merely a suitable

arrangement owing

to

inadequate offloading devices. Mr. Warner says

that the average

extraction

this year has dropped

and he puts it down to this fact. No, decidedly no.

t is due entire ly to the adoption of the methods of

chemical control laid down by the Technologists'

Association.

Mr.

Steward:

In connection

with

weighbridges,

the

first reason given in

the

paper is that it will

assist in marshalling trucks. I

can t

see how that

would occur. I think the

result

would be j ust the

reverse. you have two hundred

yards

say, of

t reble or double line

between the

weighbridge and

the carrier, you would be able to

ge t

the samples

together easier than if you have

the

weighbridge

near the

carrier. A

planter s

consignment in one

day does not come in one tr ain bu t in five or six,

and if you have

three

or four lines you can manipu-

late

the

trucks and ge t

the

samples together.

Mr. Moberly: You will notice the wording of

the

report

to

assist in the marshalling of

trucks

into samples before weighing. The idea was that

several di fferent lots may come from one man, and

you need a cer ta in

amount

of mill yard space to get

them

together. At present you 'have to weigh

them

separately.

they

could be all brought together

before they got to

the

weighbridge and you had all

your

line before the weighbridge they could be

weighed

together

in one block and simplify

the

weighbridge work.

Mr. Christianson: As to 75 of the consignment

being taken, what is meant by that; are

the

samples

to be

taken

at

one

time

or 75 in all?

Mr.

Moberly: It would depend largely on how

the

cane comes in. In

most

cases the

consignment

will all come in

together

and

the

75 would have

to be crushed of

that

consignment. Where it is

possible to collect

trucks

from different part , of the

yard and bring them together that would still 'be

done.

Mr. Pearce pointed out that the

report

had not

come before the Committee of Standardisation of

Chemical Control and was only a recommendat ion

to

that

committee.

At 12.55 p.m. the Conference adjourned.

Resumed at 2.15 p.m.

Draeger Report of the Committee

Documents

Transcript of Draeger Report of the Committee