ISO INTERNATIONAL STANDARD 3904 Second edition 1990-06-15 Shipbuildingandmarinestructures- Clear-viewscreens Constructionnavaleetstructuresmaritimes--Hublotstournants Referencenumber ISO 3904:1990(E) ISO 3904:1990(E) Foreword iso(theInternationalOrganizationforStandardization)isaworldwide federationof national standardsbodies (Isomemberbodies).Thework ofpreparingInternationalStandardsisnormallycarriedoutthroughiso technical committees. Each member body interested in a subjectfor whichatechnicalcommitteehasbeenestablishedhastherighttobe represented on that committee.International organizations, govern- mental and non-governmental, in liaison with iso, also take part in the work.so collaborates closelywith the International Electrotechnical Commission (IEC)onall matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Interna- castingavote International Standard iso3904waspreparedbyTechnical Committee Iso/TC8,Shipbuildingandmarinestructures. This second edition cancels and replaces the first edition (Iso 3904:1976),clauses4.2.4,4.5.2and7,and table3ofwhichhavebeen technicallyrevised. ISO.1990 All rights reserved. No part of this publication may be reproduced or utilized in any form orbyanymeans,electronicormechanical,includingphotocopyingandmicrofilm,without permissioninwritingfromthepublisher. InternationalOrganizationforStandardization CasePostale56·CH-1211Geneve20·Switzerland Printed in Switzerland ISO 3904:1990(E) INTERNATIONALSTANDARD Shipbuilding and marine structures -- Clear-view screens Scope screen, so that continuously clear vision through the - glass disc is ensured. This International Standard specifies the require- ments for the design and construction (including di- 4 Design and construction mensions, tolerances, materials andelectrical equipment),aswellasthedesignationandthein- stallation,of clear-view screens,principally foruse 4.1 Classification in ships. The screens shall be classified by type, according to the position of the driving electric motor (see 2 Normative references figure 1), as follows: The following standards contain provisions which, type A: Driving motor mounted at the upper part through reference in this text, constitute provisions ofthemainframeinanoffsetposition; of this International Standard.At the time of publi- cation,the editions indicated werevalid.All stan- type B: Driving motor mounted at the side of the dardsare subject torevision,and partiesto mainframeinanoffsetposition; agreements based on this International Standard are encouraged to investigate the possibility of ap- type C: Driving motor mounted at the centre of plyingthemostrecenteditionsofthestandardsin- the glass disc. dicatedbelow.Members of IEC andIsOmaintain The motor is always mounted on the inner side of registers of currently valid International Standards. the clear-view screen. Iso48:1979,Vulcanizedrubbers-Determinationof hardness(Hardnessbetween30and85IRHD) 4.2 Basic requlrements Iso3254:1989,Shipbuildingandmarinestructures 4.2.1 Drive Toughened safety glass panes for rectangular windows. Thedrive oftheglass disc shall beas follows: IEc 34, Rotating electrical machines (all parts). types A and B: by means of an endless driving belt; IEc g2, Electrical installations in ships (all parts). type C: direct. 3 Description 4.2.2 Rotational speed Thepurposeof aclear-viewscreenistoensure The rotational speed of the glass disc shall be not less than 1600 r/min. sea.Clear-view screens,according to this Interna- tional Standard, consist of a metal main frame with a rapidly rotating glass disc driven by an electric 4.2.3 Operation motor. In ordertoensurevibrationless and noiseless oper- Because of the rotation ofthe glass disc, spray,rain ation, the glass disc shall be balanced.Admissible (heavy and light). hail, sleet and snow are thrown mass excentricity in axial and radial directions is off immediately, and m