1、 ANSI/ASAE S358.3 MAY2012 (R2017) Moisture Measurement Forages American Society of Agricultural and Biological Engineers ASABE is a professional and technical organization, of members worldwide, who are dedicated to advancement of engineering applicable to agricultural, food, and biological systems.
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9、revise, or withdraw each standard. Copyright American Society of Agricultural and Biological Engineers. All rights reserved. ASABE, 2950 Niles Road, St. Joseph, Ml 49085-9659, USA, phone 269-429-0300, fax 269-429-3852, hqasabe.org ANSI/ASAE S358.3 MAY2012 (R2017) Copyright American Society of Agricu
10、ltural and Biological Engineers 1 ANSI/ASAE S358.3 MAY2012 (R2017) Approved June 2012 as an American National Standard Moisture Measurement Forages Developed by the ASAE Physical Properties of Agricultural Products Committee; approved by Electric Power and Processing Division Standards Committee; ad
11、opted December 1972; reconfirmed December 1977; revised April 1979; reconfirmed December 1983; revised by the Physical Properties of Agricultural Products Committee; approved by the Food and Process Engineering Institute Standards Committee December 1988; reaffirmed December 1993, December 1998, Dec
12、ember 1999, February 2003, February 2008, revised editorially February 2008; revised May 2012; approved as an American National Standard June 2012; reaffirmed January 2017. Keywords: Forages, Moisture 1 Purpose and Scope 1.1 This Standard establishes uniform methodology for estimating the moisture c
13、ontent of forage materials in various forms. Other techniques, such as Karl Fischer titration and toluene distillation, should be used for more accurate moisture determination. 1.2 Specification of sampling procedures is not within the scope of the Standard. It is assumed that the portion of a colle
14、cted sample used for moisture content determination is representative of the entire sample. A sample dried at temperatures above 65C will be of limited value for subsequent chemical analysis. 2 Apparatus 2.1 Sample containers. Sample containers can be one of two types depending on the timing of the
15、initial mass reading. 2.1.1 Nonhygroscopic, moisture proof containers can be used to hold samples provided the volume of contained air is minimized and covers fit tightly. Before use, dry the container for one hour at the drying temperature and obtain the tare mass. 2.1.2 Permeable containers, i.e.,
16、 cloth or paper bags, can be used provided the initial sample mass is taken immediately. Because these containers may change mass when the sample is oven dried, a small error may occur due to changes in tare mass. This can be overcome by oven drying the sample container and storing it in a moisture
17、proof container, i.e., plastic bag, until the sample is added and immediately weighing the wet sample and dry container. 2.2 Desiccator. If mass readings cannot be taken immediately at the end of the drying period, then place the sample in a desiccator. The desiccator should be airtight and should c
18、ontain a sufficient exposure of suitable desiccant to quickly lower the relative humidity of its atmosphere after loading. 2.3 Drying oven. The drying oven must be properly ventilated (mechanical convection preferred) and must have temperature sensitivity and uniformity specifications better than 2C
19、, in the range of 50 to 150C. 2.4 Balance. Sample mass should be measured to 0.001 g of the total sample mass. Results should be reported using three significant digits. ANSI/ASAE S358.3 MAY2012 (R2017) Copyright American Society of Agricultural and Biological Engineers 2 3 Procedure 3.1 Weigh the s
20、ample container. 3.2 Select a representative sample of at least 25 g. It is not necessary to chop or grind the selected samples except in the case of compacted forage products (e.g., cubes and wafers) which should be reduced in size without moisture loss so that at least one dimension of a particle
21、is less than 15 mm. 3.3 Place the sample in the sample container. 3.4 Weigh the sample container plus sample. 3.5 Place the sample container plus sample in the drying oven. Covers must be removed while the sample is being dried in the oven. 3.6 Dry the sample in the oven. 3.6.1 If the sample is for
22、moisture determination only and does not contain volatile components (i.e. fermented forage), dry at 103C for 24 h. 3.6.2 If the sample will be used for additional chemical analysis or if it contains volatile components, dry at 55C for 72 h. 3.6.3 For rapid approximate moisture determination, dry in
23、 a microwave oven, with at least 600 W, at full power until mass reading changes during three-minute intervals are sufficiently small to affect the computation by no more than 1% of the final moisture content. The oven should have a carousel to provide uniform sample exposure. 3.7 On removing sample
24、s from the oven, either samples must be weighed, container covers must be replaced, or the containers must be placed in a desiccator immediately. 3.8 Weigh the sample container plus dried sample. 3.9 Record loss in mass as moisture. 3.10 Calculate moisture content as follows: =SampleWetofMass100Mass
25、inLosspercent)(wbMCor =SampleDryofMass100MassinLosspercent)(dbMCwhere: MC (wb percent) = Moisture Content Wet Basis, percent MC (db percent) = Moisture Content Dry Basis, percent 3.11 Indicate whether the moisture content figure reported is wet basis or dry basis. References 1. Farmer, G. S. and G.
26、H. Brusewitz. 1980. Use of home microwave oven for rapid determination of moisture in wet alfalfa. Transactions of the ASAE 23(1): 170-172. 2. Fisher, Karl. 1935. A new method for the analytical determination of the water content of liquids and solids. Angew. Chem. 48: 394-396. 3. Windham, W. R., J. A. Robertson, and R. G. Leffler. 1987. A comparison of methods for moisture determination of forages for near infrared reflectance spectroscopy calibration and validation. Crop Science 27:777-783.
