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Analysis of trash and its quantitative estimation need not be overemphasised. The present paperdeals with the performance evaluation of two types of trash measuring systems mainly ShirleyTrash Analyser and HVI system. Authors conclude that their existed poor agreement in parametersobtained from two systems for Indian cotton. The paper discusses these findings in more detail.

The measurement of trash ornon- l in t conten t i s veryimportant in assessing the lintquality of cotton samples. Thecot ton C lasser or Graderestimates visually the trashcontent of a cotton sample,hence, his c lass i f icat ion issubjective. For quantitativeestimation of the trash or non-l in t conten t in a sample ,usua l ly the Sh i r ley TrashAnalyser is used. 1.2 In theLabora tory techn ique, acarefully weighed quantity of100 gms of the material ispassed through the Analyser. 3The separated lint and trashare we ighed and thepercentage of trash or non-lintcontent is determined.

One drawback o f Sh i r leyAnalyser method is that i tcannot provide informationrelating to the number or sizeof non-lint particles. This hasprompted the development ofvarious optical - electronictechniques for measuring thenumber and physical featuresof non-lint particles found onthe sur face o f raw cot tonsamples. Donald and Barker4

adopted an instrument whichemploys a television camerato view the sample to be

analysed and a special isedcomputer-based signal analysissystem to analyse the signalfrom the camera. The signalanalyser can determine anddisplay information concerningthe number, size distribution,length and area of particlesviewed by the camera.

The working group on "Dustand Trash" at the Internationalcotton conference in Bremen(1990) recommended ShirleyAnalyser Mark II, Microdustand Trash Monitor (MTM) fromUster Technologies, USA andITV Dust and Trash Tester fromHol l ingwor th as s tandardinstruments.5 The old ShirleyAna lyser was notrecommended as it does notoffer a possibility of measuringdust.

The High Volume Instrumentwas deve loped by theSPINLAB dur ing the ear lyeighties. A rapid measure oft rash conten t which i scompatible with HVI systemwas needed. The t rashdetermination method in theHVI system is based on imagedata analysis technology. Theopt i ca l scann ing method(video camera) is used in the

measurement o f t rash ,providing a measure of thesample surface area (% AREA)covered by t rash and thenumber (COUNT) of particles.The two HVI system (SpinlabHVI system and the MotionControl HVI system) measuretrash in a similar way, althoughusing different pixel spacing.A video camera optically scansa sample compressed against aviewing window above thecamera. In the Motion ControlHVI systems the viewing areais divided into a matrix of59500 raster points (pixels) or248 x 240 raster lines. Darktrash particles (i.e. those whosecolour value is 30% darkerthan the light cotton colour ofthe environment) are counted.

The Area is calculated by therelationship,

Area = 40 (Nx), where

Nx is the number of pixels

darkened by t rash . The

COUNT i s g iven by the

relationship,

* M/s Makhanlal Rajkumar Cotton Ginning

and Trading Pvt. Ltd., Bombay.

QUALITY CONTROL

MEASUREMENT OF TRASH BY SHIRLEY TRASHANALYSER AND HVI SYSTEM

Mr.K.B. Rajagopal, Miss. I.K.P. Iyer and Mrs. Mangla Srinivasan*CIRCOT, Matunga, Bombay - 400 019.

Journal of the Textile Association - May 1994 15

Count - (10) Nc, where Nc isnumber of t imes the videosignal switches from light todark.

The Area and Count are usedto calculate the LEAF number.

In order to assess thecompara t ive per formancebetween the Shirley Analyser,which measures the absolutetrash and the HVI transmeterwhich measures the surfacetrash, a study was undertakenat CIRCOT. Twenty threecot ton samples o f var iousvarieties were chosen for thispurpose. Initially, the trashpercentage was determinedusing the Shirley Analyser inCIRCOT. The trash analysisfor the same samples was doneon HVI - 900 system installedin the cotton testing laboratoryof M/s.Makhanlal RajkumarCotton Ginning and TradingPvt. Ltd., Bombay. Maximumcare was taken to minimise theloss of trash while handling the

samples. Table 1 gives the testdata of all the samples. Thetrash percentage obta inedfrom Shirley Analyser is foundto be very poorly correlatedwi th Area percentage andTrashcount obtained from HVI.The correlation coefficientswere 0 .1512 and0.4624,respectively. Similarly,the product of Area percentageand Trashcount, which givesan idea of the Leaf numberwas also poorly correlated withTrash percentage(corelationcoefficient: 0.3748).

However, the work carried outby Sasser6 indicates that theHVI t rash parameters a recomparab le wi th Sh i r leyAnalyser visible waste. Amongthe systems, Motion Controltrash parameters were morecor re la ted wi th Sh i r leyAnalyser visible waste. Barkerand Donald7 compared theoptically measured non-lintconten t w i th g rade as

subject ive ly ass igned by acotton classer for Americanupland cottons and found acurve l inear dependencebetween the object ive andsubjective trash rankings.

Hunter 8 no ted tha t eventhough HVI Trashmeters areeasy to ca l ib ra te and ares t a b l e , i n t e r - l a b o r a t o r yreproducibility of results doesnot appear to be acceptable.Recently the same windowsize, image area and referencetile have been adopted by thetwo manufacturers of HVIsystems. The reason for thepoor agreement between thetrash parameters obta inedfrom Shirley Trash Analyserand HVI systems, for Indiancottons, is proposed to beanalysed in greater detail.

Acknowledgement

The Authors are thankful toDr.N.B Patil, Director, CIRCOT.for the necessary guidance andpermission to publish this note.

REFERENCES

1. ANON., Text Mfr., 60, 111 (1934)2. Pfeiffenberger, G.W., Text. Res J., 14,

50(1944)3. Gupte, V. V., and Iyengar, R. L. N.,

Indian Cotton Gr.Rev.,13, 101(1959 )4. Donald W. Lyons and Roger.L Barker,

"Optical Measurement of Non-lintparticles in Various Grades of Cotton",P. No. 135, Text. Res J., February1976.

5. International Cotton Conference,Bremen, 1990 (Chapter 13/1)

6. Dr. P. E. Sassar, " High VolumeInstrument Test System : a total tool fortextile manufacturing" ; InternationalCotton Conference, Bremen 1984.

7. Roger L. Barker and Donald W.Lyons,"Instrument Analysis fo the influence ofNon-lint trash and Lint colour on theGrading of cotton; P. 289, Text.Res J., April, 1977.

8. Dr.Lawrance Hunter, "HVI Technology :Its Use and Misuse" , ICAC Recorder,9, No. 3, September 1991.

Journal of the Textile Association - May 1994

SR . VARIETY SHIRLEY HVI 900 SYSTEMNO . TRASH% AREA% TRASH (TRASH

COUNT COUNT XAREA%)

1 LRA 5166 � � 3.50 1.20 29.00 34.802 " � � 2.70 1.40 23.00 32.003 " � � 2.50 0.70 32.00 22.404 " � � 4.60 1.10 48.00 52.805 " � � 5.10 0.90 30.00 27.006 " � � 4.30 1.40 34.00 47.607 " � � 5.00 1.10 36.00 39.608 MECH 1 � � 2.70 1.30 30.00 39.009 J. 34 � � 5.00 0.60 34.00 20.4010 J. 34 S/G � � 3.40 0.30 28.00 8.4011 DIGVIJAY � � 3.00 0.80 44.00 35.2012 F. 414 � � 3.20 1.00 26.00 26.0013 " � � 3.80 1.80 26.00 46.8014 AHH. 44 � � 4.40 1.30 27.00 35.1015 G. COT 12 � � 5.00 1.40 66.00 92.4016 " � � 4.80 1.10 26.00 28.6017 DCH. 32 � � 1.90 1.00 26.00 26.0018 DCH. 32 � � 2.40 1.30 27.00 35.1019 S. 6 � � 4.90 1.60 42.00 67.2020 S. 6 � � 4.10 1.50 45.00 67.5021 NHH. 44 � � 3.00 1.20 26.00 31.2022 MCU. 5 � � 3.20 0.60 25.00 15.0023 JAYADHAR � � 4.00 1.80 66.00 118.80

Table-1

16