FLOW VELOCITY MEASURING UNIT

Abstract: The present invention relates to the field of control and measuring technology. In order to prevent its fouling, the flow velocity measuring unit is fitted with a gravitational filter which consists of pipes having a length at least three times greater than their diameter.

Description: Field of the Invention The invention relates to the field of control and measuring technology, and more exactly, to a unit for measuring the flow of continuous optically transparent mediums (gases, liquids, etc.), and can be used in optical flow velocity measuring units based on Doppler methods. Background Art A flow velocity measuring unit is known which comprises an optical unit including a laser and a photodetector (SU No. 1053005, 1982). However, the known apparatus does not ensure sufficiently accurate measurement because of the possibility of contamination of elements of the optical unit with impurities in the medium being studied. A flow velocity measuring unit is known which comprises an optical unit including a laser and a photodetector (SU No. 48 836, 1973). However, and this known apparatus does not exclude contamination of elements of the optical unit with impurities of the medium being studied, and this reduces the accuracy of measurement. A similar device is known from EP-A-677 722. Disclosure of the Invention The object at the base of the invention is to create an apparatus which would ensure the necessary accuracy of measurement with high reliability. The technical result is reduction of possible contamination of elements of the optical unit with impurities of the medium being studied. This object is achieved in a flow velocity measuring unit comprising an optical unit including a laser and a photodetector, in that a gravitational filter made in the form of a pipe having a length at least three times greater than the diameter thereof is introduced into the measuring unit, the pipe is disposed above the surface of a pipeline, wherein one end of the pipe is mounted in an aperture made in the pipeline, and an optical unit is secured on the other end of the pipe. Furthermore, according to the invention, the gravitational filter is provided with a shut-off cock. The essence of the invention is that the presence of a gravitational filter with a pipe of a certain length and diameter makes it possible to create a zone of stagnation of the medium being studied, for example, gas, at the input of the optical unit, and this makes it possible to substantially reduce contamination of the elements of the optical unit. Brief Description of the Drawings A functional diagram of the proposed apparatus is shown in the drawing. Best Method of Carrying Out the Invention A flow velocity measuring unit comprises an optical unit 1 with a laser, photodetector and recorder (not shown in the drawing), and a gravitational filter 2 made in the form of a pipe 3 in which a shut-off cock 4 is mounted. One end of the pipe 3 of the gravitational filter 2 is mounted on the upper generatrix of a pipeline 5 in an aperture 6 and is secured, for example, by means of welding. The optical unit 1 is secured on the other end of the pipe 3 by means of for example, a threaded connection. The length L of the pipe exceeds by more than three times its diameter D. The apparatus operates in the following manner. When the apparatus is turned on with the shut-off cock 4 open, measurement of the flow velocity of a medium, for example, gas, begins. A laser beam, passing through the pipe 3 of the gravitational filter 2 falls on the gas flow moving in the pipeline 5 and reflected light from gas particles is received by the photodetector of the optical unit 1, and further a converted signal goes to the recorder. The gravitational filter 2 is a device which makes it possible to divide the liquid (or gaseous) flow from solid (or liquid) impurities thereof by means of the gravitational field of Earth. The presence of the gravitational filter 2 prevents the passage of different impurities of the medium being studied to the optical unit as a result of the action of gravitational forces. When the ratio of the length of the pipe 3 to its diameter is equal to or less than 3, a stagnation zone is not formed and gas impurities can fall on elements of the optical unit 1 as a result of turbulent flows, but this causes contamination and as a consequence reduction of the measurement accuracy. The presence of the cock 4 makes it possible to repair the optical unit 1 and disconnect the device if necessary. Thus, connection of the gravitational filter 2 to the input of the optical unit 1 and positioning it above the surface of the pipeline 5 on its upper generatrix makes it possible to substantially reduce the contamination of elements of the optical unit 1, and, as a consequence thereof, to enhance the reliability and the accuracy of measurement. Industrial Applicability The aforesaid advantages of the proposed apparatus ensure the possibility of wide use of that apparatus during the measurement of flows of continuous optically transparent mediums (gases, liquids, etc.).

Claims: A flow velocity measuring unit comprising an optical unit (1) including a laser and a photodetector, characterized in that a gravitational filter (2) made in the form of a pipe (3) having a length which is three times greater than the diameter thereof is introduced into the measuring unit, the pipe (3) is disposed above the surface of a pipeline (5), wherein one end of the pipe (3) is mounted in an aperture (6) made in the pipeline (5), and the optical unit (1) is secured on the other end of the pipe (3). A flow velocity measuring unit according to claim 1, characterized in that the gravitational filter (2) is provided with a cock (4).

Inventors: DEREVYAGIN ALEXANDR MIKHAILOVI, DEREVYAGIN, ALEXANDR MIKHAILOVICH
Applicants: DEREVYAGIN ALEXANDR MIKHAILOVI, DEREVYAGIN, ALEXANDR MIKHAILOVICH
Application year: 1997
Main classification: G01P5
IPC codes: G01F15, G01P5