Moisture Relationships of Plant-based Agricultural Products

ASAE D245.5 JAN01Moisture Relationships of Plant-based AgriculturalProductsApproved by the ASAE Committee on Technical Data; adopted by ASAE1948; revised 1954, 1962, 1964; revised by the Electric Power andProcessing Division Technical Committee 1968, April 1974, December1978; revised March 1980; reconfirmed December 1984, December1985; revised editorially by the Physical Properties of AgriculturalProducts Committee; approved by the Food and Process EngineeringInstitute Standards Committee February 1989; reconfirmed December1990, December 1991; reaffirmed December 1992, December 1993;reaffirmed for one year December 1994; revised October 1995; revisededitorially March 1998; reaffirmed for one year January 2001.1 Purpose and scope1.1 This standard covers data and equations on plant-based agriculturalmaterials and their products. This standard does not cover information onanimal tissue and products.1.2 This standard gives data and equations on moisture relations foragricultural products. The information is used in crop drying calculationsand in design and analysis of storage systems for the material.1.3 The data and equations given in the standard are limited in theirrange of applicability. Extrapolation of the data beyond the range ofapplicability may give erroneous results.2 Normative referencesThe following standard contains provisions that, through reference in thistext, constitute provisions of this Standard. At the time of publication, theeditions indicated were valid. All standards are subject to revision, andparties to agreements based on this Standard are encouraged toinvestigate the possibility of applying the most recent edition of thestandard indicated below. Standards organizations maintain registers ofcurrently valid standards.ASAE S352.2 DEC92, Moisture Management—Unground Grain andSeeds3 Wet-basis and dry-basis representationsWet-basis moisture contentMC W G WG DG W100%Dry-basis moisture content4 Conversion formulasMC WMC DG WG D100 MC D /100MC D 100 MC W /100MC W 100 G D /100MC W 100 G W /100MC D where MC W and MC D are in percent basis.5 Equilibrium moisture content—equilibrium relativehumidity dataTables 1a, 1b, 1c, and 1d list the experimentally recorded equilibriummoisture content (EMC)—equilibrium relative humidity (ERH) data forstarchy materials, fibrous materials and selected feedstuffs, materialshigh in oil and protein, and agricultural by-products, respectively, as wellas some background information on these data. Also, figures 1 through11 give graphical representation of the EMC-ERH data for mostcommonly utilized agricultural products.6 Isotherm equationsa. Modified Henderson equationRH1expA•TC•MC D B b. Modified Chung-Pfost equationRHexpATCDexpB•MCc. Modified Halsey equationRHexp expAB•TMC D Cd. Modified Oswin equationRH AB•T C 1MC D 1e. Guggenheim-Anderson-deBoer (GAB) equationA•B•C•RHMC D 1B•RH1B•RHB•C•RHwhere:where:MC D G WG DG D100%G W is mass of wet materialG D is mass of dry material (determined by the oven methodspecified in ASAE S352.2 or by an equivalent method)RH is relative humidityT is temperatureMC D is dry-basis moisture contentA,B,C are constants7 Isotherm equation constantsTable 2 lists isotherm equation constants and related data specificationsbased on which these constants were obtained.522 ASAE STANDARDS 2001