1、BRITISH STANDARD BS7334-5: 1992 ISO8322-5: 1991 Measuring instruments for building construction Part5: Methods for determining accuracy in use of optical plumbing instrumentsBS7334-5:1992 This British Standard, having been prepared under the directionof the Basic Data andPerformance Criteria for Civ
2、ilEngineering and BuildingStructures StandardsPolicy Committee, waspublished under the authorityof the Standards Boardand comes into effect on 31 March1992 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference BDB/4 Draft for comment 88/10403 DC ISBN 0 580
3、 20619 X Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Basic Data and Performance Criteria for Civil Engineering and Building Structures Standards Policy Committee (BDB/-) to Technical Committee BDB/4, upon which the following bodies w
4、ere represented: Association of County Councils Brick Development Association British Standards Society Building Employers Confederation Chartered Institution of Building Services Engineers Concrete Society Department of Education and Science Department of the Environment (Building Research Establis
5、hment) Incorporated Association of Architects and Surveyors Institute of Clerks of Works of Great Britain Inc. Institution of Civil Engineers Institution of Structural Engineers Institution of Water and Environmental Management Royal Institute of British Architects Royal Institution of Chartered Sur
6、veyors Society of Chief Architects of Local Authorities The following body was also represented in the drafting of the standard, through subcommittees and panels: Chartered Institute of Building Amendments issued since publication Amd. No. Date CommentsBS7334-5:1992 BSI 08-1999 i Contents Page Commi
7、ttees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 General 1 4 Procedures for optical plumbing instruments (optical plummets) 3 Figure 1 Flow diagram for accuracy-in-use tests 2 Table 1-A Optical plumbing instrument Method1: Example of field observations a
8、nd calculation 7 Table 1-B Optical plumbing instrument Method1: Field observations and calculation 8 Table 2-A Optical plumbing instrument Method2: Example of field observations and calculation 9 Table 2-B Optical plumbing instrument Method2: Field observations and calculation 10 Publication(s) refe
9、rred to Inside back coverBS7334-5:1992 ii BSI 08-1999 National foreword This Part of BS7334 has been prepared under the direction of the Basic Data and Performance Criteria for Civil Engineering and Building Structures Standards Policy Committee. It is identical with ISO8322-5:1991 “Building constru
10、ction Measuring instruments Procedures for determining accuracy in use Part5: Optical plumbing instruments” published by the International Organization for Standardization (ISO), and gives the testing procedures to be adopted for optical plumbing instruments. The series of Parts comprising BS7334 wi
11、ll assist in ascertaining whether particular measuring equipment is appropriate to intended measuring tasks; they are also intended for assessing the accuracy in use of measuring instruments in general use on construction sites. The Parts are referred to in BS5606:1990 “Guide to accuracy in building
12、”. ISO8322 consists of the following parts, under the general title “Building construction Measuring instruments Procedures for determining accuracy in use: Part1: Theory; Part2: Measuring tapes; Part3: Optical levelling instruments; Part4: Theodolites; Part5: Optical plumbing instruments; Part6: La
13、ser instruments; Part7: Instruments when used for setting out; Part8: Electronic distance-measuring instruments up to150m; Part9: Electronic distance-measuring instruments up to500m; Part10: Testing short-range reflectors. The Technical Committee has reviewed the provisions of ISO7077, to which refe
14、rence is made in the text, and has decided that they are acceptable for use in conjunction with this standard. Cross-references International Standard Corresponding British Standard ISO3534:1977 a BS5532 Statistical terminology Part1:1978 Glossary of terms relating to probability and general terms r
15、elating to statistics (Identical) ISO4463-1:1989 BS5964 Building setting out and measurement Part1:1990 Methods of measuring, planning and organization and acceptance criteria (Identical) ISO7078:1985 BS6953:1988 Glossary of terms for procedures for setting out, measurement and surveying in building
16、 construction (including guidance notes) (Identical) a ISO3534 is also related to BS4778 “Quality vocabulary” Part2:1979 “National terms”.BS7334-5:1992 BSI 08-1999 iii A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsibl
17、e 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 to iv, pages1to10, an inside back cover and a back cover. This standard has been updat
18、ed (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankBS7334-5:1992 BSI 08-1999 1 1 Scope This part of ISO8322 specifies test procedures to be adopted when determining and assessing the accuracy in use of opt
19、ical plumbing instruments (optical plummets) for measurement purposes. The procedures given in this part of ISO8322 apply when these instruments are used in building construction for surveying, check and compliance measurements, and also when obtaining accuracy data. 2 Normative references The follo
20、wing standards contain provisions which, through reference in this text, constitute provisions of this part of ISO8322. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO8322 are encouraged to inve
21、stigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO3534:1977, Statistics Vocabulary and symbols. ISO4463-1:1989, Measurement methods for building Setting-out and measu
22、rement Part1:Planning and organization, measuring procedures, acceptance criteria. ISO7077:1981, Measuring methods for building General principles and procedures for the verification of dimensional compliance. ISO7078:1985, Building construction Procedures for setting out, measurement and surveying
23、Vocabulary and guidance notes. 3 General 3.1 Before commencing surveying, check and compliance measurements, when obtaining accuracy data or setting out, it is important that the operator investigate whether the accuracy in use of the measuring equipment is appropriate to the intended measuring task
24、. This International Standard recommends that the operator carry out test measurements under field conditions to establish the accuracy achieved when he uses a particular measuring instrument and its ancillary equipment. To ensure that the assessment takes account of various environmental influences
25、, two series of measurements need to be carried out under different conditions. The particular conditions to be taken into account may vary depending on where the tasks are to be undertaken. These conditions will include variations in air temperature, wind speed, cloud cover and visibility. Note sho
26、uld also be made of the actual weather conditions at the time of measurement and the type of surface over which the measurements are made. The sets of conditions chosen for the tests should match those expected when the intended measuring task is actually carried out. See ISO7077 and ISO7078. The pr
27、ocedures are designed so that the systematic errors are largely eliminated and assume that the particular instruments are in known and acceptable states of user adjustment according to methods detailed in the manufacturers handbooks. Accuracy-in-use procedures require repeat tests to be made with th
28、e same instrumentation and the same observer, within a short interval of time. These are “repeatability conditions” as defined in ISO3534. The accuracy in use is expressed in terms of the standard deviation. 3.2 Figure 1 indicates schematically the decisions to be made when establishing that the acc
29、uracy associated with a given surveying method and particular measuring equipment is appropriate to the intended measuring task. In particular, the decisions apply when adopted by a particular operator under a range of environmental conditions which are likely to occur when the task is actually carr
30、ied out. Where the contract documentation specifies the required tolerance for the intended measuring task, it is recommended that this tolerance, which is normally given in terms of the permitted deviation P (P =2,5B) of the measuring task, be compared with the accuracy-in-use data obtained either
31、from previous accuracy-in-use tests or from general data A which indicate the expected accuracy in use of given measuring equipment. On those occasions that the previously obtained data indicate that the accuracy in use associated with the given measuring equipment does not meet the specified permit
32、ted deviation of the measuring task, consideration should be given to either selecting a different method and/or a more precise instrument or discussing with the designer the need for such a small permitted deviation. See ISO4463-1.BS7334-5:1992 2 BSI 08-1999 Assumptions: P is the permitted deviatio
33、n of the measuring task A is the accuracy in use, generally expressed as deviation A (both P and A are considered to include the dimensional variability associated with 2.5 times the standard deviationB) s are the standard deviations obtained in field tests Figure 1 Flow diagram for accuracy-in-use
34、testsBS7334-5:1992 BSI 08-1999 3 Before obtaining an overall estimate of the accuracy in use, it is recommended that each standard deviation for a given series of measurements undertaken under particular environmental conditions be compared, as indicated in Figure 1, to the specified permitted devia
35、tion. Where the comparison shows that the specified permitted deviation has not been achieved for one series of measurements, an additional series of measurements should be carried out under environmental conditions as near as possible similar to those which applied in that original series of measur
36、ements. 4 Procedures for optical plumbing instruments (optical plummets) 4.1 General The accuracy of any type of plumbing instrument is dependent on the vertical distance over which the plumbing operation is carried out. Thus the achievable accuracy in use is commonly expressed as a relative lateral
37、 deviation defined as the ratio of the accuracy achieved against the difference in height. 4.2 Types of optical plumbing instruments These are three types of optical plumbing instruments. a) Instruments with a spirit-level. A cross levelling is recommended before each observation so that the line of
38、 sight is coincident with the plumb line. b) Instruments with one compensator. The compensator ensures that the line of sight is in a vertical plane such that the plumb line is the intersection of two vertical planes perpendicular to each other. c) Instruments with two compensators. The compensators
39、 work in two planes perpendicular to each other such that the plumb line is coincident with the line of sight. Each of the three types of instruments can have either a simple telescope sight or one incorporating a laser. Optical plumbing instruments (optical plummets) are able to sight either upward
40、s or downwards or both. The procedure is the same in all cases. 4.3 Test methods for accuracy 4.3.1 General The following test procedure shall be adopted for determining the accuracy in use, by a particular survey team with a particular instrument and its ancillary equipment. Two alternative methods
41、 are proposed. The first is simpler to carry out (method1); the second is more sophisticated, needs better ancillary equipment and more calculation (method2). The ancillary equipment for method1 is the cheaper, but method2 gives an improved estimation of the accuracy in use. To minimize the effects
42、of systematic errors, it is recommended that each measurement with an optical plumbing instrument consist of two observations carried out by observing with the telescope in diametrically opposed positions. 4.3.2 Method1 The measurement results should be given in a table (see Table 1-B). An example o
43、f a completed table is given in Table 1-A. 4.3.2.1 Observations a) Design a target in such a way that marks can be made on the horizontal surface and their location read with reference to a transparent rectangular x, y grid overlay graduated in millimetres. The horizontal surface shall be formed of
44、a material which will accept pencil and can be easily wiped clean. This will ensure that successive pencil marks are not biased in any way by previous marks. Fix the transparent overlay so that it always returns to the same position. Establish such a target at a height comparable with that of the in
45、tended task and locate it approximately vertically above/below the mark over/under which the instrument is centred. The orientation of the cross-hairs of the telescope shall be parallel to the axes of the target during every observation. b) Table 1-A is an example using an optical plumbing instrumen
46、t with one compensator. Each measurement for x (or y) shall consist of two observations carried out by observing with the telescope in diametrically opposed positions. (See columns3 and5.) If an instrument with a spirit-level or with two compensators is used, each position of the telescope provides
47、values of x and y simultaneously. Thus two opposing positions of the telescope suffice. c) Record the environmental conditions. Changes in environmental conditions during the construction period may render the test result inapplicable. In such a case repeat the test under the new conditions.BS7334-5
48、:1992 4 BSI 08-1999 4.3.2.2 Calculation procedure A complete example of the analysis is given in Table 1-A, columns4,6,7,8,9 and10, for an optical plumbing instrument with one compensator using the measurements given in columns3 and5 and it is recommended that this form of presentation be generally
49、adopted. a) Calculate in column4 the mean x =(x 1 + x 2 )/2 and in column6 the mean y =(y 1 + y 2 )/2 EXAMPLE b) Calculate the means and from x 1 , x 2 .x 10and y 1 , y 2 . y 10 . EXAMPLE c) Calculate the deviations v x =(x) and v y =(y) in columns7 and9 from the arithmetic means. To minimize the effect of rounding errors, the calculation of each deviation v should be carried out to the nearest0,01mm. As an arithmetic check, the sum of the10 deviations in the x and y directions should be approximately z
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