Thermal measuring and testing – Transformation point determination – By change in optical property
Patent
1994-12-13
1997-06-24
Gutierrez, Diego F. F.
Thermal measuring and testing
Transformation point determination
By change in optical property
374 19, 356339, G01N 2512
Patent
active
056412304
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method of determining cloud points and a cloud point meter useful for the method. More particularly, this invention relates to a method of determining cloud points and a cloud point meter which use a total-reflection type wave-guide sensor connected to optical fibers to determine clouding, a phenomenon caused by the deposition or separation of solid matter, water removal, or other change in state or condition, of liquid products of chemical industry, especially petroleum products such as gas oil in the petroleum industry.
BACKGROUND ART
Gas oil, a product from the petroleum refining process, contains paraffins. Since paraffins are solid at about room temperature, an increase in the paraffin content will reduce the fluidity of the gas oil at low temperatures as in winter. When a sample of petroleum product, such as gas oil or lubricating oil, is gradually cooled in a prescribed way, its paraffin content deposits or separates increasingly until the walls of the container holding the sample begins to appear cloudy. This point is known as a cloud point. The same phenomena occur with plasticizers and surfactants. Cloud point determination is important for the specifications of petroleum products in winter. There are many other cases in which the deposition of solids upon cooling of petroleum products must be determined.
Japanese Industrial Standards K-2269 prescribes testing procedures for the cloud point of petroleum products as well as the fluid point of crude oil and petroleum products. The cloud point testing procedure is briefly defined: "Place a test tube holding 45 ml of a sample into an outer tube in a cooling bath and cool it in a prescribed manner. Take out the test tube each time the sample temperature has dropped by 1.degree. C. The temperature at which a cloudy appearance has just been seen in the bottom of the sample shall be deemed a cloud point." Remarks say: "The use of an automatic cloud point tester instead is permissible provided it is confirmed beforehand in conformity with JIS Z-8402 that there is no significant difference between the result thereby attained and the result obtained by the testing procedure defined above." As the testing equipment are furnished: a test tube in the center of which a test thermometer is held vertically with a cork stopper in place, outer tubes each fitted with a bottom disk of cork or felt and adapted to house the test tube therein, and cooling baths each equipped with a thermometer for cooling solution. The test tube is able to be placed into and taken out of an outer tube through an annular gasket kept in close contact with the outer wall of the test tube. The annular gasket tightly fitted around the test tube is loosely in contact with the outer tube to support the test tube vertically therein. The testing procedure is specified to comprise:
(1) keeping a sample at a temperature higher than a predicted cloud point by at least 14.degree. C.;
(2) pouring the sample into the test tube up to the height of a marked line (at the middle);
(3) hermetically sealing the test tube with the cork stopper fitted with a thermometer, in such manner that the thermometer is held upright in the center, with its tip in contact with the bottom of the tube;
(4) placing the test tube together with the annular gasket into the outer tube fitted with a bottom disk;
(5) placing the outer tube, together with the test tube housed therein, into a first cooling bath and supporting the outer tube lest it float 25 mm or more from the surface of the cooling solution;
(6) after the sample temperature has reached the vicinity of the predicted cloud point, taking out the test tube upon each drop by .degree. C., rapidly and without causing any sample vibration, inspecting the sample for any cloudy appearance seen in the bottom, and then placing the test tube back into the outer tube; and
(7) repeating these steps and recording the reading of the thermometer at the moment when visible clouding or haze appears for the first time in the bottom of th
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Abstract of GB 1,438,754, complete specification published on 9 Jun. 1976.
Hach CR "Surface Scatter" Turbidimeter, Model 1032, Hach Chemical Company, Ames, Iowa (Nov. 1964).
Gutierrez Diego F. F.
Japan Energy Corporation
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