BS-6932-1988.pdf
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1、BRITISH STANDARD BS 6932:1988 Method for Measurement of the effective focal spot size of mini-focus and micro-focus X-ray tubes used for industrial radiography UDC 616 073.754.3:621.386.2:620.179.152:620.115.8 + 006.01 Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 05:18:57 GMT+00:00 2006, U
2、ncontrolled Copy, (c) BSI BS 6932:1988 This British Standard, having been prepared under the direction of the General Mechanical Engineering Standards Committee, was published under the authority of the Board of BSI and comes into effect on 29 January 1988 BSI 12-1999 The following BSI references re
3、late to the work on this standard: Committee reference GME/23 Draft for comment 86/77574 DC ISBN 0 580 16367 9 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the General Mechanical Engineering Standards Committee (GME/-) to Technical Commit
4、tee GME/23, upon which the following bodies were represented: Aluminium Federation Associated Offices Technical Committee Association of Consulting Engineers BEAMA Ltd. BNF Metals Technology Centre British Airways British Chemical Engineering Contractors Association British Institute of Non-destruct
5、ive Testing British Non-Ferrous Metals Federation British Steel Industry Department of Trade and Industry (National Engineering Laboratory) Electricity Supply Industry in England and Wales Engineering Equipment and Materials Users Association Health and Safety Executive Institute of Quality Assuranc
6、e Institution of Production Engineers Lloyds Register of Shipping Ministry of Defence Non-Destructive Testing Centre Society of British Aerospace Companies Limited Society of Motor Manufacturers and Traders Limited Steel Casting Research and Trade Association United Kingdom Atomic Energy Authority W
7、ater-tube Boilermakers Association Welding Institute Coopted member Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 05:18:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6932:1988 BSI 12-1999i Contents Page Committees responsi
8、bleInside front cover Forewordii 1Scope1 2Definitions1 3Test object1 4Procedure1 5Presentation of results1 Figure 1 Positioning of test object2 Figure 2 Trace produced from scanning2 Figure 3 Microdensitometer trace across image of edge of test object2 Publications referred toInside back cover Licen
9、sed Copy: sheffieldun sheffieldun, na, Tue Dec 05 05:18:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6932:1988 ii BSI 12-1999 Foreword This British Standard has been prepared under the direction of the General Mechanical Engineering Standards Committee. Whereas BS 6530 describes methods for dete
10、rmining the characteristics of focal spots in diagnostic X-ray tube assemblies for medical use, this standard is concerned with the measurement of the effective focal spot size of micro-focus and mini-focus X-ray tubes used for industrial radiography, including rod-anode tubes. The object of this st
11、andard is to enable the performance of different types of X-ray equipment to be compared and to provide a means by which such performance can be checked in service. The effective size of the focal spot is directly related to the geometric unsharpness and is therefore an important parameter that need
12、s to be known when specifying suitable radiographic techniques for various applications. It has been assumed in the drafting of this British Standard that the execution of its provisions is entrusted to appropriately qualified and experienced people. A British Standard does not purport to include al
13、l the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and
14、 ii, pages 1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 05:18:57 GMT+00:00
15、2006, Uncontrolled Copy, (c) BSI BS 6932:1988 BSI 12-19991 1 Scope This British Standard describes a method for measuring effective focal spot sizes within the range 5 4m to 300 4m of X-ray tubes operating at 50 kV to 200 kV. NOTE 1The same procedure may be used at higher kilovoltages but the accura
16、cy of measurement may be poorer. NOTE 2For focal spot sizes greater than 300 4m, the pinhole and other methods detailed in BS 6530:1984 may usually be applied. NOTE 3The titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of thi
17、s British Standard the definitions given in BS 3683-3 apply. 3 Test object The test object shall consist of an accurately machined high precision spherical ball of tungsten carbide, having a diameter of 5 mm. The ball shall be mounted on a thin aluminium alloy support plate having a thickness of app
18、roximately 0.5 mm by means of adhesive which does not extend beyond the periphery of the ball. To minimize extraneous scattered radiation, the support plate carrying the ball shall be mounted across a circular aperture of approximately 12 mm diameter in a lead sheet having a thickness of approximate
19、ly 3 mm, in such a manner that the ball is located in the centre of the aperture. In order to obtain the necessary projective magnification value, the mounting plate shall be of a size that enables the test object to be positioned very close to the target of the X-ray tube. 4 Procedure 4.1 Select th
20、e required kilovolt and milliamp settings and adjust the X-ray equipment to obtain the best focus in the centre of the X-ray field. NOTEThis can be conveniently achieved by means of a series of very fine wire meshes (commonly known as TEM grids) and an image intensifier system. Record the readings o
21、n the control. 4.2 Place the test object in the X-ray beam, the tungsten carbide ball being as nearly as possible in the centre of the X-ray field. Adjust the distance of the test object and the imaging plane to provide approximately 20 projective magnification (see Figure 1). 4.3 Take a radiograph
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