The '''Cleveland open-cup method''' is one of three main methods in chemistry for determining the [[flash point]] of a [[petroleum]] product using a '''Cleveland open-cup apparatus''', oralso known as a '''Cleveland open-cup tester'''.<ref>[https://www.astm.org/Standards/D92.htm "Standard Test Method for Flash and Fire Points by Cleveland Open Cup Tester"], ASTM.org</ref> First, the test cup of the apparatus (usually brass) is filled to a a certain level with a portion of the product. Then, the temperature of this chemical is increased rapidly and then at a slow, constant rate as it approaches the theoretical flash point. The increase in temperature will cause the chemical to begin to produce flammable [[vapor]] in increasing quantities and density. The lowest temperature at which a small test flame passing over the surface of the liquid andcauses causingthe itvapor to ignite is considered the chemical's [[flash point]]. This apparatus may also be used to determine the chemical's [[fire point]] which is considered to have been reached when the application of the test flame produces 5at least five continuous seconds of ignition. Temperature range of this apparatus is 120 to 250 degree c<ref>{{Cite book |editorn editor-last = Wray |editorn editor-first = Harry A. | coauthors = American Society for Testing and Materials | title = Manual on flash point standards and their use: methods and regulations | publisher = ASTM International | date = September 1992 | ___location = Baltimore, MD | pages = | url = | doi = | id = | isbn = 08031141090-8031-1410-9}}</ref>
The other principal methods of establishing chemical flash points are the [[Pensky-MartensPensky–Martens closed-cup methodtest]] and the [[Tagliabue cup method]] method (often called simply the "Tag method").▼
▲The other principal methods are the [[Pensky-Martens closed cup method]] and the [[Tagliabue cup method]] (often called simply the "Tag method").
