Method of Determining and Expressing Fineness of Feed

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ANSI/ASAE S319.3 JUL97 Approved JUL 1997 by American National Standards Institute

Method of Determining and Expressing Fineness of Feed Materials by Sieving Proposed initially by a subcommittee of the American Feed Manufacturers Association; approved by the ASAE Electric Power and Processing Division Technical Committee; adopted by ASAE December 1968; reconfirmed December 1973, December 1978, December 1983; revised March 1985; revised by the ASAE Food and Grain Processing and Storage Committee; approved by the Food and Process Engineering Institute Standards Committee December 1989; revised editorially November 1990; reaffirmed December 1994, December 1995; revised October 1996; approved as an American National Standard July 1997.

1 Purpose and scope 1.1 The purpose of this Standard is to define a test procedure to determine the fineness of feed ingredients and to define a method of expressing the particle size of the material. Surface area and number of particles per unit mass can be calculated from the determined particle size. 1.2 This Standard should be used to determine the fineness of feed ingredients where the reduction process yields particles which are primarily spherical or cubical. It is not adequate to define the particle size of materials such as steamed and rolled grains, which are a flaked product, or products such as chopped hay where a substantial fraction consists of elongated particles. 1.3 This Standard is compatible with ISO 565, ISO 2395, ISO 2591-1, ISO 3310-1, and ISO 9276-1.

2 Normative references The following standards contain provisions which, through references in this text, constitute provisions of this Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Standards organizations maintain registers of currently valid standards. ASTM E11-95 Specification for Wire-Cloth Sieves for Testing Purposes ASTM D1921-89 Test Methods for Particle Size (Sieve Analysis) of Plastic Materials ASTM D4749-87 Test Method for Performing the Sieve Analysis of Coal and Designating Coal Size ASTM D4570-86 Test Methods for Rubber Chemicals—Determination of Particle Size of Sulfur by Sieving (Dry) ISO 565:1990 Test sieves—Metal wire cloth, perforated metal plate and electroformed sheet—Nominal sizes of openings ISO 2395:1990 Test sieves and test sieving—Vocabulary ISO 2591-1:1988 Test sieving—Part 1: Methods using test sieves of woven wire cloth and perforated metal plate ISO 3310-1:1990 Test sieves—Technical requirements and testing—Part 1: Test sieves of metal wire cloth ISO 9276-1:1990 Representation of results of particle size analysis—Part 1: Graphical representation

3 Definitions The following is a list of the definitions for the terms related to this Standard. Refer to ISO 2395 for more general terminology of test sieving. 3.1 aperture size: Dimension defining an opening. ASAE STANDARDS 1998

3.2 blinding: Obstruction of the apertures of a sieving medium by particles of material being sieved. 3.3 charge: A test sample, or part of a test sample, placed on a test sieve or a nest of test sieves. 3.4 cumulative oversize distribution curve: A curve obtained by plotting the total percentages by mass retained on each of a set of sieves of descending aperture size against the corresponding aperture sizes. 3.5 cumulative undersize distribution curve: A curve obtained by plotting the total percentages by mass passing each of a set of sieves of descending aperture size against the corresponding aperture sizes. 3.6 dispersion agent: Non-toxic chemicals that help break up agglomerates. 3.7 end-point: The point in time after which further sieving fails to pass an amount sufficient to change the result significantly. 3.8 frame: A rigid framework that supports the sieving medium and limits the spread of the material being sieved. 3.9 log-normal standard deviation: The standard deviation of the logarithm of particle diameters in a log-normal size distribution curve (refer to equation 2). 3.10 median size: Particle diameter at 50% probability of a size distribution curve. Equivalent to geometric mean diameter (see equation 1). 3.11 nest of test sieves: A set of test sieves assembled together with a lid (cover) and a receiver (pan). 3.12 oversize: That portion of the charge that has not passed through the apertures of a stated sieve. 3.13 sample: A representative part taken from a quantity of material. 3.14 sieving: The process of separating a mixture of particles according to their size by means of one or more sieves. 3.15 size distribution curve: A graphical representation of the results of a size analysis. 3.16 test sieve: A sieve, intended for the particle size analysis of the material to be sieved, that conforms to a test sieve standard specification. 3.17 undersize: That portion of the charge that has passed through the apertures of a stated sieve. 3.18 woven wire cloth: A sieving medium of wires that cross each other to form the apertures.

4 Test equipment 4.1 A set of woven wire-cloth sieves having a frame diameter of either 200 mm (ISO 565) or 203 mm (8 in.) (ASTM Standard E11) are used. With the most common shaking equipment, sieves having a height of 25 mm (1 in.) or half-height sieves are most suitable to avoid the necessity of resieving the finer fraction. These sieves should consist of the aperture sizes shown in table 1. 4.2 A sieve shaker, such as a Tyler Ro-Tap1) or equivalent unit, is required. 4.3 A balance that can weigh to an accuracy better than 0.1% of the charge mass should be used. 1)

Registered trade name 547

5.6 If 20% or more of the material by mass passes the smallest sieve, the fine material should be subjected to a non-sieving particle size analysis, such as microscopic measurement or sedimentation testing, and such analysis should be reported separately.

Table 1 – Aperture sizes for test sieves ISO 3310-1 supplementary sizes R40/3

US sieve no.

(mm) 4.75 3.35 2.36 1.70 1.18

4 6 8 12 16

(mm) 4.76 3.36 2.38 1.68 1.19

(in.) 0.187 0.132 0.0937 0.0661 0.0469

4 6 8 10 14

20 30 40 50 70 100 140 200 270

(µm) 841 595 420 297 210 149 105 74 53

0.0331 0.0234 0.0165 0.0117 0.0083 0.0059 0.0041 0.0029 0.0021

20 28 35 48 65 100 150 200 270

(µm) 850 600 425 300 212 150 106 75 53 Pan

US sieve opening

Tyler designation

4.4 Sieve agitators such as plastic or leather rings, or small rubber balls may be required to break up agglomerates on finer sieves, usually those smaller than 300 mm in opening (ISO 3310-1) or US sieve No. 50. 4.5 A dispersion agent2) should be used to facilitate sieving of high-fat or similar materials. 4.6 Sieve openings must be kept free of feed particles so that normal sieving can be accomplished. A stiff bristle sieve cleaning brush, or compressed air, is useful for cleaning sieves clogged due to blinding. Sieves must be cleaned periodically to remove oil. Oil can be removed by washing with water containing a detergent. Sieves must be dried before use.

5 Method of sieving 5.1 A charge of 100 g should be used, although larger or smaller charges may be used if necessary. Extra care shall be taken to recover all material from the sieves when smaller charges are used. 5.2 Place the charge on one sieve or the top sieve of the nest of test sieves and shake until the mass of material on any one sieve reaches end-point. End-point is decided by determining the mass on each sieve at 1-min intervals after an initial sieving time of 10 min. If the mass on the smallest sieve containing any material changes by 0.1% or less of the charge mass during a 1-min period, the sieving is considered complete. For industrial applications, the end-point determination process can be omitted, and the end-point is set to be the sieving time of 15 min. 5.3 For hand-sieving, take the test sieve or nest of test sieves in one hand, or cradle it in the crook of the arm if too heavy. Incline the sieve (or the nest) at an angle of about 20° with the point at which the sieve is held in the lower position, and tap the sieve (or nest) approximately 120 times a minute with the other hand. After tappings, return the test sieve to a horizontal position, turn 90° and give a hard tap by hand against the sieve frame. From time to time the sieve may also be shaken vertically. 5.4 Mass of material on all sieves should be determined and recorded. 5.5 If a dispersing agent is required, it should be added at a level of 0.5% relative to total charge mass, and its effect on particle size need not be considered. 2)

Dispersion agents include Cab-O-Sil MS available from the Cabot Corp., Boston; Ziolex 23A and Zeofree 80 available from the J. M. Huber Corp., New York; and Flo-Gard available from the Pittsburgh Plate Glass Co., St. Louis.

548

6 Data analysis 6.1 Particle size data can be presented in histograms, density distributions and cumulative distributions. The procedures and nomenclature specified in ISO 9276-1 apply to this Standard. 6.2 Calculation of particle size, surface area, and number of particles by mass calculations is based on the assumption that particle sizes of all ground feeds and feed ingredients are logarithmic-normally distributed. 6.2.1 The size of particles can be reported in terms of geometric mean diameter (or median size) and geometric standard deviation by mass. 6.2.2 Calculation formulas, based on the derivations by Pfost and Headley (1976) and Sokhansanj and Yang (1996), are as follows:

F G n

d gw 5log

s log5

F

21

( i 51

~ W i log d i !

( i 51

Wi

n

( i 51

(1)

n

W i ~ log d i 2log d gw ! 2 n

( i 51

Wi

G

1/2

5

S ln 2.3

1 S gw ' d gw @ log21 S log−(log21 S log)−1] 2

(2)

(3)

where:

di d i 11 d gw

S log

is nominal sieve aperture size of the i th sieve, mm is nominal sieve aperture size in next larger than ithsieve(just above in a set), mm is geometric mean diameter or median size of particles by mass, mm is geometric mean diameter or median size of particles on ith sieve, mm is ( d i 3 d i 11 ) 1/2 is geometric standard deviation of log-normal distribution by mass in ten-based logarithm, dimensionless

S ln

is geometric standard deviation of log-normal distribution by mass in natural logarithm, dimensionless S gw is geometric standard deviation of particle diameter by mass, mm is mass on ith sieve, g Wi n is number of sieves +1 (pan) S log can, in addition to equation 2, also be determined by graphical method as:

S log5log

S D S D d 84 d 50 5log d 50 d 16

(4)

1 S gw ' ~ d 84 2 d 16 ! 2

(5)

where:

d 84

is

particle diameter at 84% probability

d 50

is

particle diameter at 50% probability

d 16

is

particle diameter at 16% probability ASAE STANDARDS 1998

6.2.3 Material passing a 53-mm sieve (ISO 3310-1) or US sieve No. 270 should be considered to have a mean diameter of 0.045 or 0.044 mm, respectively, and di is equal to 0.045 mm or 0.044 mm, respectively. The geometric mean diameter (or median size) of particles larger than the aperture size of 4.75 mm (ISO 3310-1) or US sieve No. 4 is determined by using the 6.70 mm sieve (ISO 3310-1) or US sieve No. 3 with a sieve aperture size of 6.73 mm (4.76 3 &) as the i th 1 1 sieve. 6.2.4 The equation for estimating the total surface area of particles in a charge is:

A st 5

b sW t exp~ 4.5 s ln2−ln m gw ! b vr

(6)

where:

A st is estimated total surface area of a charge, cm2

b s is shape factor for calculating surface area of particles. Cubical, b s 5 6; Spherical, b s 5 p b v is shape factor for calculating volume of particles. Cubical, b v 5 1; Spherical, b v 5 p/6 r is particle density of the material, g /cm3 s ln is log-normal geometric standard deviation of parent population by mass in natural logarithm, use S ln as an estimate m gw is geometric mean particle diameter of parent population by mass, cm, use d gw as an estimate (Note: m gw is expressed in cm and d gw in mm) W t is mass of a charge, g

d gw 5log21

S log5

F

(7)

( ~ W i log d i ! (Wi

G

5log21

( W i ~ log d i 2log d gw ! 2 ( Wi

F

G

221.986 50.591 mm 96.3

G S D 1/2

11.256 5 96.3

1/2

50.341

50.512 mm The geometric mean diameter (or median size) ( d gw ) and log-normal geometric standard deviation ( S log) may also be obtained graphically by plotting the summed percentages in table 2 (( P i , %