Understanding Standardization Cottons
Fiber testing instruments are ud extensively in the lection of cotton for standards. This method ensures uniformity and accuracy in duplicating the standards in each t from year to year as long as the standard remains in effect.
The Cotton Program conducts crop surveys and other special studies to determine if any changes are needed in grade or other standards to accurately describe the cotton currently being produced or marketed. When a revision or change in standards becomes necessary, the Program notifies the overas Signatory Associations and all major U.S. cotton industry groups of the propod changes. After giving final consideration to the propod standards at the next Universal Cotton Standards Conference, the Advisory Committee on Cotton Standards recommends action on the proposals to the Secretary. If the Secretary adopts the propod standards, they become effective in one year as required by the U.S. Cotton Standards Act.
The USDA's official color and leaf grade standards for American Upland cotton have also been the Universal Cotton Standards since 1924. USDA is signatory to the Universal Cotton Standards Agreement with 24 cotton merchant and spinners associations in 21 countries in Europe, South Americ
a, and Asia. The agreement provides for (1) the adoption, u, and obrvance of the Universal Standards in the classification of U.S. Upland cotton, and (2) the preparation, distribution, and protection of copies of the Universal Standards. Conferences are held every three years in the United States to ensure accurate reproduction of the standards and to consider any revisions needed in the standards. In addition to reprentatives from the overas signatory associations, reprentatives of producers, ginners, shippers, exchanges, and other gments of the cotton industry in the United States attend and participate in the work of the conferences and the Advisory Committee on Cotton Standards.
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In respon to a USDA proposal considered at the triennial conference in 1995, USDA's calibration standards for HVI measurements were incorporated into the Universal Standards Agreement. The proposal had broad support from the U.S. cotton industry becau all U.S. cotton is clasd by USDA's High Volume Instruments (HVI), and most sales by growers are bad on this HVI classification data. The overas signatory associations overwhelmingly supported the proposal also. While the pace of movement of the cotton industry in changing official cotton standards is conrvative, the commitment to adopt to more efficient technology appears to be strong in the U.S. and abroad.新东方魏公村校区
Official measurements for Fiber Length, Length Uniformity Index, Fiber Strength, Micronaire, Color, and Trash are performed by High Volume Instruments. Official clasr determinations are made for leaf grade, and extraneous matter.
The cotton standards and other materials ud for classing cotton, are listed below:
改变自己英文(1) Color Grade of American Upland Cotton - Color Grade describes the color of cotton lint. There are standards for 25 color grades of upland cotton and five categories of "below grade" color. Fifteen of the grades are reprented in physical form by boxes of cotton reprenting the full range of each standard, while the remaining 10 grades and five below grade categories are descriptions bad on the physical color grade standards.
(2) Leaf Grade of American Upland Cotton - Leaf grade describes the leaf or trash content in the cotton. There are ven leaf grades designated as leaf grade A1" through A7" , and all are reprented by physical standards. In addition, there is a descriptive Abelow grade@ (leaf grade 8) designation.
The current rerve t of the Universal Standards for Color and Leaf Grades of American Upland Cotton is aled and deposited in a vault in Memphis, TN. Copies of the standards, containing six
samples or biscuits, known as practical forms, are prepared and sold for $125
The color of cotton deepens with age more in the high grades than in the low grades. The color of the cotton in the standards may differ considerably as time goes by, especially when the standards are stored under extreme conditions of temperature and/or relative humidity. Becau of this natural propensity for change, copies of the grade standards must be freshly prepared annually and are effective for one year beginning each July 1.
(3) Grades of American Pima Cotton - There are six official grades (Grades A1" through A6") for American Pima cotton, all reprented by physical standards. In addition, there is a descriptive "below grade" designation. Copies of the American Pima Grade Standards are sold for $b. Memphis, or $165, surface delivery.
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(4) Fiber Length, Length Uniformity Index, and Fiber Strength - The Cotton Program us High Volume Instruments for the classification of all Upland and American Pima cotton. There are Universal HVI Calibration Standards for American Upland cotton for calibrating length, length uniformity index, and strength. The prent official standards for fiber or staple length provide for various lengths in terms of inches and fractions of an inch ranging from 13/16 inches upward, generally in graduations of one thirty-conds of an inch. The upper half mean length of fiber is measured by the HVI system in hundredths of an inch and length is converted to thirty-conds of an inch. Length uniformity index is the ratio between the mean length and the upper half mean length expresd as a percentage. Fiber strength is measured in grams per tex and reprents the force in grams to break a bundle of fibers one tex unit in size. Both the Universal HVI Calibration Standards for Upland cotton and the USDA HVI Calibration Cottons for American Pima cotton are available, in 5-pound boxes, for $b. Memphis, TN or $100 domestic delivery. Two such cottons, which span a range in length and strength, are required for instrument calibration.
(5) Micronaire - Official cotton standards for micronaire or fiber fineness and maturity are described as the measure of such qualities provided by air flow instrument tests in terms of micronaire readings in accordance with established procedures. The procedures include descriptions of appr
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oved weighing and testing equipment and standard operating instructions for the equipment. Mike readings are expresd in units to the nearest one tenth, (e.g. 3.1, 3.2, 3.3, 3.4); however, common practice within the industry is to drop the decimal point when reporting "mike" readings (e.g. 31, 32, 33, 34). Mike readings of American Upland cotton range from 2.4 to 6.0. About 75 percent of the cotton crop falls in the 3.5 to 4.9 range.
instrumentThe Cotton Program participates and manages the International Calibration Cotton Standards (ICCS) Program which, under the guidance of the ICCS Committee, establishes standard values
for International Calibration Cottons. Currently, there are six International Calibration Cotton Standards for Micronaire Only that span the range of micronaire scale from 2.6 to 5.5. The price for a 1-pound roll of the micronaire-only calibration cotton standards is $b. Memphis, or $31 domestic delivery. This price also includes the cost of a miannual check test program which aids in achieving a common test level on a global basis. Each laboratory that purchas calibration cottons receives two samples for check tests each six-month period, and upon return of data, receives a report on its results compared to other participants. The standards have been purchad by more than 500 laboratories worldwide, and about 250 of the laboratories participated in the most recent miannual check test. In addition to the miannual check test, a quarterly chec
记忆力不好怎么办k test for micronaire equipment is available to overas arbitration laboratories. This program, which ensures a common level of test results, is available for a fee of $21 per quarter per laboratory.
(6) Trash - The trash measurement is made by the HVI video trashmeter which measures the percentage area and particle count of trash on the sample's surface. A trashmeter calibration tile and cotton trash level samples, mounted under glass, are available for calibration and verification of the trash measurements. The cost of the trash tile is $b. Memphis, TN or $33 domestic delivery. The cost of the trash level samples is $b. Memphis, TN ($240 for full t of six) or $44 domestic delivery ($264 for full t of six). The range of trash levels usually encountered is included in a t of six samples.
(7) Color - The HVI colormeter measures reflectance (Rd) and yellowness (+b). The Rd indicates the sample's degree of grayness and +b indicates how much yellow color is in the sample. Ceramic color calibration tiles for the HVI colormeter are distributed by the Cotton Program. The cost for a five tile t is $b. Memphis, TN or $130 domestic delivery. (8) Other Standards - There are also Universal Standards for descriptions of laboratory atmospheric conditions and conditioning practices and procedures. In addition, a brochure entitled "Guidelines for HVI Testing" has been prepared that contains standardized procedures for HVI testing which will enable urs of HVI syste
ms to achieve a common test results level for each measured property.
ancePrograms for Checking HVI Measurements - An HVI Check Test Program is conducted to ensure a standard level of testing. Two samples are nt to participants each month for testing. The returned data are summarized and each participant receives a report comparing their results to established values for the samples. The annual cost of the HVI check test program is $168 domestic and $324 overas. An HVI Level Asssment Program was initiated in 1993 in respon to the worldwide proliferation in the u of HVI measurements in trading Upland cotton in the world markets. Participants submit check samples that have been tested by HVI for retesting by the Quality Assurance Unit in much the same manner as the Cotton Programs internal supervisory procedures. The participant receives a report showing how well the results of the two tests compare. This program has been beneficial in achieving a common test level worldwide. Cost for this program is $4 per sample in lots of 10 samples.
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Summary - USDA's cotton standards are ud almost exclusively within the U.S. and are broadly accepted in the foreign marketing of Upland-type cotton, especially that grown in the United States. The standards provide a sound ba for establishing market values that gain more acceptance with each year's crop. International trading disputes are ttled by utilizing U.S. standards. The check te
st programs contribute to the growing confidence in USDA's cotton standards and also ensure a common level of test results for all urs.
