1.1 This test method covers the determination of the unit cell dimension of zeolites having the faujasite crystal structure, including synthetic Y and X zeolites, their modifications such as the various cation exchange forms, and the dealuminized, decationated, and ultra stable forms of Y. These zeolites have cubic symmetry with a unit cell parameter usually within the limits of 24.2 and 25.0 Å (2.42 and 2.50 nm). 1.2 The samples include zeolite preparation in the various forms, and catalysts and adsorbents containing these zeolites. The zeolite may be present in amounts as low as 5 %, such as in a cracking catalyst. 1.3 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 determine the applicability of regulatory limitations prior to use. 1.4 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.