1、BRITISH STANDARD BS7470:1991 ISO3904:1990 Specification for Clear-view screens for use in shipsBS7470:1991 This BritishStandard, having been prepared under the directionof the General Mechanical Engineering Standards Policy Committee, waspublished under the authorityof the Standards Board and comes
2、into effect on 30August1991 BSI11-1999 The following BSI references relate to the work on this standard: Committee reference GME/32 Draft announced in BSI News August1991 ISBN 0 580 19909 6 Committees responsible for this British Standard The preparation of this BritishStandard was entrusted by the
3、General Mechanical Engineering Standards Policy Committee (GME/-) to Technical Committee GME/32, upon which the following bodies were represented: British Marine Equipment Council British Maritime Technology British Motor Ship Owners Association British Waterways Board Department of Transport (Marin
4、e Directorate) General Council of British Shipping Lloyds Register of Shipping Ministry of Defence North East Coast Institution of Engineers and Shipbuilders Shipbuilders and Shiprepairers Association Amendments issued since publication Amd. No. Date CommentsBS7470:1991 BSI 11-1999 i Contents Page C
5、ommittees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Description 1 4 Design and construction 1 5 Designation 3 6 Glass disc (designated by code letter Y) 3 7 Installation 3 Figure 1 Types and main dimensions of screen 2 Figure 2 Glass disc 4 Figure 3 Ins
6、tallation dimensions of screen 4 Table 1 Main dimensions of screen 1 Table 2 Mechanical properties of material for main frame 2 Table 3 Current systems 3 Table 4 Main dimensions of glass disc 4 Table 5 Installation dimensions of screen 4 Publication(s) referred to Inside back coverBS7470:1991 ii BSI
7、 11-1999 National foreword This BritishStandard has been prepared under the direction of the General Mechanical Engineering Standards Policy Committee. It is identical with ISO3904:1990 “Shipbuilding and marine structures Clear-view screens”, published by the International Organization for Standardi
8、zation (ISO). The Technical Committee has reviewed the provisions of ISO3254:1989, IEC34 and IEC92, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. A British Standard does not purport to include all the necessary provisions
9、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. Cross-references International Standard Corresponding British Standard ISO48:1979 BS903 Methods of testing vulcanized
10、 rubber PartA26:1969 Determination of hardness (Technically equivalent) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments inco
11、rporated. This will be indicated in the amendment table on the inside front cover.BS7470:1991 BSI 11-1999 1 1 Scope This International Standard specifies the requirements for the design and construction (including dimensions, tolerances, materials and electrical equipment), as well as the designatio
12、n and the installation, of clear-view screens, principally for use in ships. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. A
13、ll standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standar
14、ds. ISO48:1979, Vulcanized rubbers Determination of hardness (Hardness between30 and85IRHD). ISO3254:1989, Shipbuilding and marine structures Toughened safety glass panes for rectangular windows. IEC34, Rotating electrical machines (all parts). IEC92, Electrical installations in ships (all parts). 3
15、 Description The purpose of a clear-view screen is to ensure clear vision in any weather condition or in heavy sea. Clear-view screens, according to this International Standard, consist of a metal main frame with a rapidly rotating glass disc driven by an electric motor. Because of the rotation of t
16、he glass disc, spray, rain (heavy and light), hail, sleet and snow are thrown off immediately, and moisture does not cling to the screen, so that continuously clear vision through the glass disc is ensured. 4 Design and construction 4.1 Classification The screens shall be classified by type, accordi
17、ng tothe position of the driving electric motor (seeFigure 1), as follows: type A: Driving motor mounted at the upper part of the main frame in an offset position; type B: Driving motor mounted at the side of the main frame in an offset position; type C: Driving motor mounted at the centre of the gl
18、ass disc. The motor is always mounted on the inner side of the clear-view screen. 4.2 Basic requirements 4.2.1 Drive The drive of the glass disc shall be as follows: types A and B: by means of an endless driving belt; type C: direct. 4.2.2 Rotational speed The rotational speed of the glass disc shal
19、l be not less than1600r/min. 4.2.3 Operation In order to ensure vibrationless and noiseless operation, the glass disc shall be balanced. Admissible mass excentricity in axial and radial directions is given in Table 4. 4.2.4 Clearance The distance (clearance) between the outside edge of the complete
20、glass disc and the main frame of the clear-view screen shall not be greater than2mm. 4.2.5 Main frame The height of the main frame shall be such as to ensure that it can be installed in glass panes with nominal thicknesses up to19mm, in accordance with ISO3254. 4.2.6 Glass disc See clause6. 4.3 Main
21、 dimensions The main dimensions of the screens shall be as given in Table 1 and Figure 1. The figures do not define the construction; they are only intended to indicate the standardized dimensions. Table 1 Main dimensions of screen Dimensions in millimetres Type A B C Nominal size a 280 330 380 280
22、300 350 a max. 455 555 575 405 b max. 205 230 255 175 c max. 45 45 45 20 93 93 d 1 0,5 310 360 410 275 339 389 d 2 356 406 a The nominal size is derived from the outside diameter of the glass disc: see Table 4.BS7470:1991 2 BSI 11-1999 4.4 Materials 4.4.1 Main frame The main frame shall be manufactu
23、red from aluminium alloy or copper alloy having the minimum mechanical properties specified in Table 2. Table 2 Mechanical properties of material for main frame 4.4.2 Other metal components Metal components, other than the main frame, shall be manufactured from aluminium alloy, copper alloy, or corr
24、osion-resistant steel. 4.4.3 Seals The seals shall be made from natural or synthetic rubber, having the following properties: hardness35IRHD to40IRHD (IRHD=International Rubber Hardness Degrees), in accordance with ISO48; seawater-resistant; ultra-violet light-resistant. 4.5 Electrical equipment 4.5
25、.1 Cables, switchgear, control gear and transformers The electrical equipment shall be in accordance with the requirements of IEC92. 4.5.2 Electric motors The electric motors shall be in accordance with the recommendations of IEC34. They need not be of totally enclosed construction (degree of protec
26、tion IP33 according to IEC92) as they are situated inside the ship. Motors shall be designed with a power output to ensure that the required speed specified in4.2.2 is obtained in all weather conditions. Figure 1 Types and main dimensions of screen Code letters Material Tensile strength min. Elongat
27、ion min. AL Aluminium wrought alloy 140N/mm 2 3% CU Copper alloyBS7470:1991 BSI 11-1999 3 4.5.3 Current systems See Table 3. Table 3 Current systems 4.5.4 Radio-interference suppression devices All clear-view screens shall be fitted with radio-interference suppression devices as generally provided o
28、n-board ships. 4.5.5 Provisions for de-icing Normally de-icing means do not form part of the construction of a clear-view screen. Clear-view screens shall, however, be designed to ensure that, if desired, the subsequent installation of de-icing means may be carried out. 5 Designation Complete clear-
29、view screens conforming to this International Standard shall be designated as follows, in the order given: a) denomination: “Clear-view screen”; b) number of this International Standard: ISO3904; c) type(4.1); d) nominal size (Table 1); e) code letters of material of main frame (Table 2); f) current
30、 system identification number (Table 3). EXAMPLE The designation for a clear-view screen type A of nominal size330mm, main frame made of copper alloy (CU), for a.c. three phase supply, voltage220V, with a frequency of60Hz (identification No.34), is: Clear-view screen ISO3904-A-330-CU-34 6 Glass disc
31、 (designated by code letterY) 6.1 Dimensions and tolerances The glass disc shall meet the dimensions and tolerances shown in Figure 2 and given in Table 4. 6.2 Material The glass disc shall be made of clear toughened safety glass in accordance with ISO3254. 6.3 Designation Glass discs for clear-view
32、 screens according to this International Standard shall be designated as follows, in the order given: a) denomination: “Disc”; b) number of this International Standard: ISO3904; c) type: Y (clause6); d) outer diameter d 3(Table 4). EXAMPLE The designation for a glass disc (Y) of diameter d 3 =330mm
33、is: Disc ISO3904-Y-330 7 Installation Clear-view screens may be fitted in rectangular ships windows (and wheel-house windows) or directly in metal walls. The diameter, d 5 , of the hole (cut-out) shall be as given in Table 5. If clear-view screens are fitted inrectangular ships windows the minimum d
34、istance, e, from the circumference of the hole to the dimensions of the clear light size of the window shall be as given in Table 5 (see Figure 3). Supply Voltage V Frequency Hz Identification number d.c. 24 01 110 02 220 03 a.c. single phase 115 50 11 60 12 220 50 13 60 14 a.c. three phase 115 50 3
35、1 60 32 220 50 33 60 34BS7470:1991 4 BSI 11-1999 Table 4 Main dimensions of glass disc Table 5 Installation dimensions of screen Figure 2 Glass disc Dimensions in millimetres d 3 0,5 280 300 330 350 380 d 4 0,5 26 t 0,3 8 Admissible bow in the middle ofthe disc max. 0,5 0,6 0,7 Deviation from parall
36、elism between the two surfaces ofthe disc max. 0,2 Admissible mass excentricity in axial direction max. 0,5 Admissible mass excentricity in radial direction max. 0,7 Figure 3 Installation dimensions of screen Dimensions in millimetres Type A B C Nominal size 280 330 380 280 300 350 d 5 312 1 362 1 4
37、12 1,25 278 1 341 1 391 1 e min. 50 50 50 50 50 50BS7470:1991 BSI 11-1999 Publication(s) referred to See national foreword.BS7470:1991 ISO3904:1990 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards.
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