Disclosure to Promote the Right To Information

Transcription

1 इ टरन ट म नक Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. ज न1 क अ+धक र, ज 1 क अ+धक र Mazdoor Kisan Shakti Sangathan The Right to Information, The Right to Live प0र 1 क छ ड न' 5 तरफ Jawaharlal Nehru Step Out From the Old to the New IS 5706 (1993): Optical instruments - Spirit levels for use in precision engineering [PGD 22: Educational Instruments and Equipment]! न $ एक न' भ रत क +नम-ण Satyanarayan Gangaram Pitroda Invent a New India Using Knowledge! न एक ऐस खज न > ज कभ च0र य नहB ज सकत ह ह Bhartṛhari Nītiśatakam Knowledge is such a treasure which cannot be stolen

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4 IS 5706:1993 Indian Standard OPTICAL INSTRUMENTS - SPIRIT LEVELS FOR USE IN PRECISION ENGINEERING - SPECIFICATION ( First Revision _) UDC c81 : BIS 1993 BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI June 1993 Price Group 2

5 Optical and Mathematical Instruments Sectional Committee, LM 20 FOREWORD This Indian Standard ( First Revtsion ) was adopted by the Bureau of Indian Standards, after the draft finalized by the Optical and Mathematical Instruments Sectional Committee had been approved by the Light Mechanical Engineering Division Council. This standard was first published in In this revision clauses 3.1 to 3.7 on terminology have been incorporated. This standard covers three types of levels used in precision engineering with accuracy ranging from 0.05 mm/m to 0.1 mm/m at 27 C. Taking into consideration the views of producers, consumers and testing authorities, the Sectional Committee responsible for the preparation of this standard felt that it should be related to the manufacturing and trade practices followed in the country in this field. Furthermore, due weightage had been given to the need for international co-ordination among standards prevailing in different countries of the world in this field. Metric system has been adopted in India and all dimensions in this standard have been given in this system. For the purpose ~of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with IS 2 : 1960 Rules for rounding off numerical values ( revised j. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. This standard is intended chiefly to cover the technical provisions relating to bubbles, and it does not include all the necessary provisions of a contract.

6 IS 5706 : 1993 Indian Standard OPTICAL INSTRUMENTS - SPIRIT LEVELS FOR USE IN PRECISION ENGINEERING - SPECIFICATION ( First Revision ) 1 SCOPE This standard specifies the features and requirements of spirit levels used in precision engineering. 2 REFERENCE 2.1 IS 1632 : 1992 COptical instruments - Bubbles - Specification (first revision ) is a necessary adjunct to this standard. 3 TERMINOLOGY 3.0 For the purpose of this standard, the following definitions in addition to those given in IS 1632 shall apply. 3.1 Roll Error The longitudinal movement of the bubble ( due to imperfections in the ground surface of the vial ) when rolled through a specified angle about its axis. 3.2 Repeatability The measure of the ability of the level to repeat its readings under all ordinary methods of operation. 3.3 Settling Time The time taken for a bubble to return to its steady position when the vial has been tilted through a specified angle. 3.4 Flatness Tolerance The maximum permissible distance between two imaginary parallel planes within which the surface under consideration can just be enclosed. 3.5 Squareness Tolerance The maximum permissible distance separating two imaginary parallel planes which just enclose one of the surfaces under consideration and which are perpendicular to the other surface. Squareness tolerance is expressed over the total length of one of the surfaces. 3.6 Parallelism Tolerance The maximum permissible variation in distance between the surfaces under consideration. 3.7 Sensitivity That angle of tilt which causes the bubble in the vial to move through one scale division. 4 TYPES, SIZES AND ACCURACIES 4.1 The levels shall be of the following types Type 1 A block level with an unrelieved flat base of cast iron ( see Fig. 1 ). This type of level shall usually be made with base lengths from about 100 mm to 200 mm Type 2 A block level, usually of cast iron or steel, having a base formed with flat bearing surfaces at the two ends, that is, the middle portion is relieved ( see Fig. 2 ). The bearing surfaces may either be plain or contain a longitudinal 120 V-groov~e for use on cylindrical surfaces. In the latter case a short cross bubble with sensitivity of IO minutes or small circular level is provided This type of level shall usually be made with base lengths from about 250 mm to 500 mm. The length of the bearing surfaces shall be at least 2/9 of the length of the spirit level Type 3 A square block level usually of cast iron and of 200 mm square ( see Fig. 3 ). The four bearing surfaces shall be flat and may have the middle portions relieved; alternatively the base and one adjacent surface may each contain a longitudinal 120 V-groove for use on cylindrical surfaces. In the latter case a short cross bubble with sensitivity of IO minutes shall be provided. 4.2 Accuracy The recommended accuracies of all types of levels for precision engineering shall be from 0.05 mmjmetre to 0.1 mm/metre at 27 C. 1

7 IS 5706 : 1993 BASE JUSTMENT.- H FIG. 1 TYPE 1 LEVEL CROSS LEVEL PROVIDED WHEN VEE GROOVE INCORPORATED ADJUSTMENT BASE I FIG. 2 TYPE 2 LEVEL -- USTMENT S LEVEL PROVIDED WHEN VEE GROOVES INCORPORATED PUG. 3 TYPE 3 LEVEL [ 1 20 VEE GROOVE (OPTIONAL IN BASE AND ONE ADJACENT SIDE: 5 DESIGNATION 6 GENERAL REQUIREMENTS 5.1 The designation Of Spirit level shall include 6.1 The spirit levels shall conform to the the following: requirements given in to a) Type of level, b) Type of bearing surface ( P - plain The cylindrical glass vials and circular bearing surface, and I/ _ longitudinal glass vials when used shall conform to all the V-groove ), requirements given in IS 1632 : c) Base length, d) Accuracy, and To minimize the differences in thermal expansion between the glass vial and its mount, e) Number of this standard. the glass should have a co-efficient of thermal Example : expansion approximating to that of the material A spirit level of type 2 having a plain bear- of the mount. To allow for any residual ing surface and base length of 250 mm shall difference in expansion, the glass vial should be designated as: preferably be mounted so as to permit slight Level 2 P mm/m IS 5706 : 1993 relative longitudinal movement. 2

8 6.1.3 It is recommended that the dimensions of the glass vial should be such that both ends of the bubble can always be read against the scale over a temperature range of 10 C to 40 C. To achieve this, it is recommended that the alteration in the length ofthe bubble for a temperature change of 1 C betneeen 10 C and 40 C should not exceed I percent of its length at 27 C Glass vials of levels may preferably be protected by a permanent transparent cover All unmachined surfaces on the level shall be painted with a high-grade enamel paint _or should have an equivalent protective finish The weight of the levels shall be kept to the minimum; consistent with stability to avoid undue deflection of the surfaces on which the level is supported when in use Each level shall be supplied in a suitable protective case. The case shall be suitabiy padded from inside and shall be provided with securing arrangements. 6.2 Type 1 Levels The hardened base shall be lapped to provide a wringing surface and shall be flat overall to within 0,001 mm. Any departure from flatness shall be in the nature of a concavity and not a convexity. In order to maintain this degree of flatness, the body af this type of level shall be stabilized. NOTE - The following stabilizing process is recommended: The hardened body of the level, before final grinding, shall be heated and maintained at a temperature of 150~2 for a period of 5 to 10 hours and allowed to cool slowly in the furnace. 6.3 Type 2 Levels The base, including the 120 V-groove where provided, shall be finished by scraping, grinding or lapping. The bearing surfaces of the base and the sides of the V-groove shal.1 be flat and co-planar to within mm for levels up to 300 mm long and 0*004 mm for larger levels. The V-grove when provided shall be parallel to the base to within the equivalent of half of a scale division. ( mm per 100 mm for 5 second levels, 0,002 5 mm per 100 mm for 10 second levels and mm per 100 mm for 20 second levels ). 6.4 Type 3 Levels The four surfaces of the square of Type 3 levels, including the V-groove where provided, shall IS 5706 : 1993 be finished by scraping, grinding or lapping, and each surface and each side of the V-groove shall be flat and co-planar to within mm. Adjacent working surfaces of the square shall be square to each other and opposite working faces shall be parallel to each other to within the equivalent of half of a scale division. Each V-groove shall be parallel to its own flat ( upper ) surface to within the same amount. 7 FUNCTIONAL REQUlREMENTS 7.1 Each level shall incorporate a means of adjusting the level to zero. This adjustment shall be such that when the level is placed on a horizontal surface, it shall be possible to adjust the level so that the two ends of the bubble give equal readings on the scale to within one-tenth of a division The adjustment shall be provided with an efficient locking device and as far as possible, shall be proofed against tampering At the standard reference temperature of 27 C the length of the bubble should be equal to the distance between the centre lines of the scales to within one-half of a division Sensitivity consistency and roll of the bubble shall conform to Table 2 of IS 1632 : TESTS 8.1 Zero Setting The level shall be tested for its zero setting in accordance with Sensitivity, Consistency of the Bubble The bubble shall be tested for its sensitivity, consistency, roll, sluggishness, total error and heat in accordance with 7.1, 7.2, 7.3, 7.4, 7.5, 7.6 and 7.7 respectively of IS 1632 : Flatness of the base shall be tested with the help of optical Rats The V-grooved surfaces shall be tested as follows: The level shall be placed over a movable stage which has been properly levelled earlier. Then with the help of a dial gauge, the vertical face of the level shall be made parallel to the axis off horizontal movement of the stage. Now the point of another dial gauge with accuracy mm shall be brought in fine contact with one of the surfaces of the V-groove and the movable stage shal! then be moved slowly along the horizontal axis. The variation on the dial gauge shall not be more than f mm

9 IS 5706 : 1993 at any point. In this way the entire surface of the V-groove shall be tested. 8.4 Squareness Squareness shall be tested either by an autocollimator or with the help of a precision square tester. 9 MARKING 9.1 The glass vial used in the level shall be suitably and legibly marked preferably near the centre with their measured values of sensitivity. 9.2 The name of the manufacturer or his trademark and the year of manufacture shall be suitably marked on the level Standard Mark Datails available with the Bureau of Indian Standards. 10 PACKING AND PACKAGING 10.1 During storage and transit all working surfaces of the level shall be protected against climatic conditions by being covered with a suitable corrosion preventive compound. The level shall then be placed in its protective case. The case shall be wrapped with brown paper and required number of cases shall be suitably packed in a wooden box lined with brown paper using any suitable material for cushioning An instructional booklet shall be provided by the manufacturer giving specially the precautions to be taken during use. 4

10 Standard Mark _~-- The use of the Standard Mark is governed by the provisions of the Bureau of Indian Standards Act, 1986 and the Rules and Regulations made thereunder. The Standard Mark on products covered by an Indian Standard conveys the assurance that they have been produced to comply with the requirements of that standard under a well defined system of inspection, testing and quality control which is devised and supervised by BIS and operated by the producer. Standard marked products are also continuously cheked by BIS for conformity to that standard as a further safeguard. Details of conditions under which a licence for the use of the Standard Mark may -be granted to manufacturers or producers may be obtained from the Bureau of Indian Standards I I

11 Bureau of Indian Standards BIS~is a statutory institution established under the Bureau of Zndian Standards Act, I986 to promote harmonious development of the activities of standardization, marking and quality certification of goods and attenting to connected matters in the country. Copyright BIS has copyright of all its publications. No part of these publications may be reproduced in any form without the prior p-ermission in writing of BIS. This does not preclude the free use, in the course of implementing the standard, of necessary details, such as symbols and sizes, type or grade designations. Enquiries relating to copyright be addressed to the Director ( Publications ), BIS. Revision of Indian Standards Amendments are issued to standards as the need arises on the basis of comments, Standards are also reviewed periodically; a standard along with amendments is reaffirmed when such review indicates that no changes are needed; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standards should ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of BIS Handbook and Standards Monthly Additions. Comments on this Indian Standard may be sent BIS giving the following reference: Dot : No. LM 20 ( 0010 ) Aendments Issued Since Publication Amend No. Date of Issue Text Affected BUREAU OF INDIAN STANDARDS Headquarters: Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi Telephones : , Telegrams : Manaksanstha ( Common to all Offices ) Regional Offices : Central : Manak Bhavan, 9 Bahadur Shah Zafar Marg NEW DELHI Eastern : l/14 C. I. T. Scheme VII M, V. I. P. Road, CALCUTTA Maniktola Northern : SC , Sector 35-C, CHANDIGARH Southern : C. I. T. Campus, IV Cross Road, MADRAS Telephone i I ( , t , r , ~ l , , Western : Manakalaya, E9 MIDC, Marol, Andheri ( East ) r , BOMBAY , Branches : AHMADABAD. BANGALORE. BHOPAL. BHUBANESHWAR. COIMBATORE FARIDABAD. GHAZIABAD. GUWAHATI. HYDERABAD. JAIPUR. KANPUR. LUCKNOW. PATNA. THIRUVANANTHAPURAM. Printed at Printwell Printers, Aligarh, India