SANS 6150-2010 Verification of compression testing machines for concrete Calibration of load scale《混凝土抗压试验机的检查：负载规模校准》.pdf

1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA

2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any

3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-23120-0 SANS 6150:2010Edition 2.1SOUTH AFRICAN NATIONAL STANDARD Verification of compression testing machines for concrete: Calibration of

4、 load scale Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 6150:2010 Edition 2.1 Table of changes Change No. Date Scope Amdt 1 2010 Amended to update referenced standards. Foreword Thi

5、s South African standard was approved by National Committee SABS SC 59A, Construction standards Cement, lime and concrete, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was published in February 2010. This document su

6、persedes SANS 6150:2006 (edition 2). A vertical line in the margin shows where the text has been technically modified by amendment No. 1. SANS 6150:2010 Edition 2.1 1 Contents Page Foreword 1 Scope 3 2 Normative references 3 3 Applicability . 3 4 Apparatus 3 5 Initial inspection of testing machine 4

7、 6 Setting up the proving device . 4 7 Selecting the calibration forces . 5 8 Preliminary conditioning of the testing machine . 6 9 Calibration . 6 10 Calculations 6 11 Grading of load indicator . 8 12 Report . 8 SANS 6150:2010 Edition 2.1 2 This page is intentionally left blank SANS 6150:2010 Editi

8、on 2.1 3 Verification of compression testing machines for concrete: Calibration of load scale 1 Scope This standard describes a method to verify the accuracy of compression testing machines for concrete. 2 Normative references The following standards contain provisions which, through reference in th

9、is text, constitute provisions of this standard. All standards are subject to revision and, since any reference to a standard is deemed to be a reference to the latest edition of that standard, parties to agreements based on this standard are encouraged to take steps to ensure the use of the most re

10、cent editions of the standards indicated below. Information on currently valid national and international standards can be obtained from the SABS Standards Division. ISO 7500-1, Metallic materials Verification of static uniaxial testing machines Part 1: Tension/compression testing machines Verificat

11、ion and calibration of the force-measuring system. SANS 10159, Measurement and calibration systems. Amdt 1 SANS 17025/ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories. 3 Applicability The method is used to verify the accuracy of the load scale indicator

12、reading of machines used for compression testing of concrete test specimens. The test specimens are principally concrete cubes but may include blocks, bricks and similar building components. NOTE Materials testing machines should be verified annually or after major repairs or adjustment, or after tr

13、ansfer to a new site. 4 Apparatus 4.1 Proving device, such as a proving ring, load cell or standardizing box: a) the calibration of which is traceable to a recognized national standard (see SANS 17025); and Amdt 1 b) that is accurate to within 0,25 % or better over the loading range of the machine.

14、SANS 6150:2010 Edition 2.1 4 4.2 Bearing plates, for use with the proving device. Steel plates ground to a true surface and of hardness at least 400 HV30 and preferably of thickness at least 50 mm. The area of the plates is such that the maximum pressure on the surface of the machine platens does no

15、t exceed 100 MPa. NOTE The bearing plates are used to protect the platens and to make up height. 5 Initial inspection of testing machine NOTE 1 The initial inspection, which should be carried out by a person who is qualified by virtue of his training and experience, is carried out to allow the testi

16、ng authority to decide whether the machine is in such a condition that it can be verified. NOTE 2 In this standard reference is made to ISO 7500-1. 5.1 Operate the machine in accordance with the manufacturers instructions and ascertain whether: a) it is in good working order; b) it can be effectivel

17、y controlled; and c) the loading element operates without excessive vibration. NOTE Excessive vibration has a detrimental effect on both the proving device and the sample that is tested in the machine. 5.2 On the basis of the outcome of 5.1, decide whether the verification can continue. 6 Setting up

18、 the proving device 6.1 Select an appropriate combination of proving device and bearing plates to match (preferably within 3 mm) the height of the test specimens that are usually tested in the machine. NOTE The intention is that the calibration of hydraulically operated machines be performed with th

19、e ram in its normal working position. In many cases, however, the proving device with its bearing plates will not be equal in height to the common specimen being tested and unless the upper machine platen height is adjustable, other options of adjustment of the platen opening can be considered in or

20、der to accommodate the proving device while retaining the normal working position. Testing machines are generally provided with removable platen spacers which, when used in conjunction with suitable bearing plates, provide a wide range of adjustment. 6.2 Determine and record the ram position by mean

21、s of one of the following methods: a) If the upper platen height is not adjustable, measure and record the distance between the two platens when the upper platen touches the upper bearing plate on the proving device. b) If the upper platen height is adjustable, raise the loading ram from its positio

22、n of rest to its normal working position and record this rise (extension) in relation to a convenient reference point. 6.3 So position the proving device between the platens and bearing plates that its axis coincides to within 1 mm with the loading axis of the testing machine. 6.4 Before recording t

23、he measurements, a) allow all electronic equipment to operate for at least 10 min or in accordance with the manufacturers instructions, b) if the testing machine has a tarring device, raise the loading ram well clear of its normal position of rest and, while the ram is rising, set the load indicator

24、 of the testing machine to zero. SANS 6150:2010 Edition 2.1 5 7 Selecting the calibration forces 7.1 General Select the values of force (indicated on the scale of the testing machine) at which measurements are to be recorded. Select at least five values (excluding zero) approximately equally spaced

25、between zero and the required maximum force, and ensure that the first reading is not below the lower limit of calibration. The first reading shall be at approximately 20 % of the maximum calibration force reading or at the lower limit of calibration of the scale, whichever is the greater. 7.2 Lower

26、 limit of calibration Determine the lower limit of calibration Fv(which is a function of the resolution and the intended grading value in accordance with ISO 7500-1) using the following equation: FV= a r where a = 400 for grade 0,5 machines; 200 for grade 1,0 machines; 100 for grade 2,0 machines; r

27、is the resolution, in units of force, as determined in 7.3. 7.3 Analogue scale (dial and recorder) Subdivide the smallest marked scale interval to determine the resolution r in accordance with table 1. Table 1 Determining the resolution 1 2 Width of scale interval Resolution, in units of force I mm

28、r 2,5 I 1/10 of scale interval 1,25 I I 1/2 of scale interval 7.4 Digital scale Determine the resolution when no force is applied by the testing machine and take it to be one-half of the range of fluctuation on the digital read-out or one increment count, whichever is the greater. 7.5 Example A comp

29、ression testing machine with an analogue scale has a scale interval of width 3 mm which represents 2 kN. From table 1, the resolution r is 1/10 of the scale interval, that is r = 1/10 2 = 0,2 kN. SANS 6150:2010 Edition 2.1 6 Therefore the lower limit of calibration FVfor a) a 0,5 grade machine = 400

30、 0,2 = 80 kN; b) a 1,0 grade machine = 200 0,2 = 40 kN; and c) a 2,0 grade machine = 100 0,2 = 20 kN. 8 Preliminary conditioning of the testing machine Allow the testing machine to exert and release the maximum calibration force three times at approximately the normal rate of loading and, after the

31、third application, lower the ram to its normal position of rest. NOTE Repeat clause 8 for every change of proving device introduced, for example, when other scales of the machine are verified using a different proving device. 9 Calibration 9.1 Allow a period of approximately 2 min for the machine in

32、dicator to stabilize and, if necessary, reset the indicator to zero while raising the ram slowly through its free travel. 9.2 Apply the selected calibration forces in order of increasing magnitude with the maximum force indicator (if present) in operation. At each selected value, record the readings

33、 that are given on both the machine and the proving device. If difficulty is experienced in maintaining a steady force, measurements may be made under conditions of slowly increasing force. 9.3 After the maximum calibration force has been applied and the corresponding measurements on the proving dev

34、ice recorded, remove the force and lower the ram to its position of rest. 9.4 Raise the ram slowly and record, as the zero-force value, the indicated reading of the machine during the free travel of the ram, then lower the ram to its position of rest. 9.5 Repeat 9.1 to 9.4 twice more to obtain a tot

35、al of three sets of readings for the zero-force condition and a total of three sets of readings for the calibration forces. 9.6 Record the ambient temperature. 10 Calculations 10.1 General Take true force to be that derived from the reading on the proving device by applying the calibration data and

36、temperature correction factors of the device. The average true force is the average of the three true forces corresponding to one value of calibration force on the testing machine. SANS 6150:2010 Edition 2.1 7 10.2 Calculation of error For each calibration force, calculate the following: Fe= mmtFFF

37、100 where Feis the error of testing machine force scale, as a percentage; Ftis the corresponding average true force; Fmis the force recorded on the testing machine. 10.3 Calculation of repeatability For each calibration force, calculate the repeatability of force values using the equation: Fr= mg 1F

38、FF 100 where Fris the repeatability of force values, as a percentage; Fgis the maximum true force; F1is the minimum true force; Fmis the corresponding machine-indicated force. 10.4 Calculation of zero-force error The zero-force error is given by: Fze= max.zFF 100 where Fzeis the zero-force error, as

39、 a percentage; Fzis the average zero-force recorded on the testing machine (see 9.4); Fmax.is the full scale reading of the testing machine. SANS 6150:2010 Edition 2.1 8 10.5 Expression of calculated percentage Except as given in table 2, round off percentages to the nearest 0,1 %. Table 2 Expressio

40、n of calculated percentages for grading purposes 1 2 Calculated percentage P Expressed percentage P = 0 0 0 P 0,06 0,1 0,06 P 0,1 0,1 11 Grading of load indicator Grade the load indicator in accordance with table 3. NOTE The testing machine may be graded in terms of columns 2, 3 and 4 or any combina

41、tion of these. Table 3 Grading of load indicator 1 2 3 4 Maximum error Maximum repeatability of force values Maximum zero-force error Grading of testing machine % % % 0,5 0,5 0,5 0,1 1,0 1,0 1,0 0,2 2,0 2,0 2,0 0,4 12 Report Produce a report that gives the following information: a) the name and addr

42、ess of the customer; b) the description of the testing machine; c) the make of the testing machine; d) the serial number of the testing machine; e) the capacity of the testing machine; f) the calibration site or location of the testing machine; g) the method of calibration, stating 1) the words “Cal

43、ibrated in accordance with SANS 6150, 2) the ram position in terms of either the distance between the platens or the ram extension; SANS 6150:2010 Edition 2.1 9 h) a description and serial number of the calibration equipment used; i) the tabulated calibration results including forces indicated on th

44、e testing machine, true forces and percentage error; j) the machine grading with respect to 1) accuracy of force scale, 2) repeatability of force values, and 3) zero force error; k) the date of verification; l) the re-verification date; m) the relevant remarks relating to the calibration; and n) the

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