1.1. This test method describes the apparatus and procedure needed for determining the fluidization behavior of free-flowing powders as Geldart Group A or B using a fluidization chamber consisting of a right circular cylinder. 1.1.1. This test method is for powders that are readily or easily fluidizable and fall into the category of Group A or B of the Geldart classification. 1.1.2. Geldart classification of powders is often used to predict the fluidization behavior of a free-flowing powder which is represented in Figure 1 126.96.36.199. Geldart Group A powders are easily fluidized, but there is a significant difference between the gas velocity at which the bed is initially fluidized and the velocity at which bubbles are first observed. For Geldart Group A powders, bed expansion can be considerable before any bubbles are observed. 188.8.131.52. Geldart Group B powders are also easily fluidized, but there is little to no difference between the velocity at which the bed is fluidized and the velocity at the onset of bubbling. The minimum gas velocity at which all of the particles are fully supported by the gas for Geldart Group B powders is often referred to as the complete fluidization velocity instead of minimum fluidization velocity. 184.108.40.206. Geldart Group C powders are cohesive and often difficult to fluidize. 220.127.116.11. Geldart Group A powders can also be distinguished from Geldart Group B powders by the response to deaeration. Geldart Group A powders deaerate relatively slowly whereas Geldart Group B powders deaerate almost instantaneously for fluidized beds less than about 300 mm in bed height. 18.104.22.168. Powders that lie near or on the Geldart A/C boundary may be tested by this method. However, if the powders do not fluidize freely, test results should be considered invalid. 1.2. This test method should be performed in a laboratory under controlled conditions of temperature and humidity. 1.3. All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026. 1.4. The procedures used to specify how data are collected/recorded or calculated, in this standard are regarded as the industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider material variations, the purpose for obtaining the data, special purpose studies, or any considerations for the users objectives; and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analysis methods for engineering design. 1.5. The values stated are in SI Units and are to be regarded as the standard. No other units of measurement are included in this standard, 1.6. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health and environmental practices and to determine the applicability of regulatory limitations prior to use. 1.7. This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Keywords14.1. Complete Fluidization:14.2. Fluidization:14.3. Geldart Group A:14.4. Geldart Group B:14.5. Minimum fluidization velocity:
1.1. This test method describes the apparatus and procedure needed for determining the fluidization behavior of free-flowing powders as Geldart Group A or B using a fluidization chamber consisting of a right circular cylinder.
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