National technical measures JJF1033-2001 "appraisal measurement standard norms" used by the standard measurement apparatus, equipment and the test carried out / calibration accuracy of the project target of completing the "uncertainty or accuracy of the level or the maximum allowable error "; JJF1069-2000" legal metrology institutes evaluation norms "fill in the requested verification / calibration of the" level of accuracy of measurements or expanded uncertainty "; national laboratories recognized by the calibration of the project was to fill in the" uncertainty / accuracy level. " More than a few expressions, in the face of it just on different characters, and the reality of the uncertainty of how to express the issue, there are different understanding and misunderstanding. For example, JJF1033-2001 standard measuring apparatus, equipment uncertainty in the interpretation of "known or the instrument measuring the indication error, and results need to be amended, fill in the indication error of measurement uncertainty"; Another JJF1033-2001 for the calibration and verification carried out by the uncertainty of the project is explained, "means the use of the measurement standards under test or calibration target given the uncertainty of results, which should not be measured by the introduction of target The uncertainty "(see JJF1033-2001 material Publicizing national unity" appraisal measurement standard guidelines for the implementation of norms ", the Chinese publishing house measurement). The apparatus of uncertainty, the same norms, have a different understanding, in other norms of the meaning of its own distinction, many experts said that the uncertainty with the characteristics of measuring instruments, it is not appropriate. In order to express the accuracy of the measuring instruments are indicators of unity and a clear understanding of the equipment level of accuracy, the maximum allowable error and uncertainty of the significance of internal relations and the analysis and discussion is essential.
First, the accuracy level is a sign that the level of accuracy
The accuracy of measuring instruments is a qualitative concept. Inthis issue JJF1001-1998 "universal measurement and definition ofthe term", JJF1059-1999 "Uncertainty in Measurement and Evaluationsaid that", BIPM, ISO, and other measures 7 internationalorganizations in 1993 "International basic terminology and commonmeasurement" (VIM), ISO, and other international organizations 7 in1993, formally promulgated the "Guide to the Expression ofUncertainty in Measurement" (GUM) has been given a clearexplanation. JJF1033-2001 "appraisal measurement standard norms,"has also JJF1033-1992 standard for measurement accuracy to give aquantitative formula for calculating the provision be amended toreplace the uncertainty of the measurement results. Clear theaccuracy of measuring instruments is a qualitative concept, as wellas international standards and norms and above line is essential.VIM is a result GUM and a number of international organizations inthe name of the promulgation of the joint internationalorganizations are also gradually eliminate non-standardformulation. For some of the inappropriate expression, such as"second-class piston gauge the accuracy of ± 0.05%", is the onlystandard, specification documents, such as amendments to correctstep by step.
Gauges the accuracy level of expression must be a point of orderbased on the measurement test, system test table, OIMLinternational recommendations, standards and other technicaldocuments. Is usually the maximum allowable error that themeasuring instruments, the capital of Latin-level figures, Romannumerals or Arabic numerals that, if necessary, can be attached toArabic letters. For example: weight divided into E1, E2, F1, F2,M1, M2, M11, M22 class. Cited by the maximum allowable error orrelative that the maximum allowable error of measuring instruments,said that the Arabic numerals, and often expressed as a percentageand leave out the percentage sign. For example: Spring-precisionpressure gauge, is divided into 0.05, 0.1, 0.16, 0.25, 0.4, 0.6.And so on according to the division of the measuring instruments,in Chinese or Arabic numerals, said the figures, such assecond-class piston pressure gauge, 3 equal pieces.
Unfortunately, by habit, there are still some people think thatsince the level of accuracy that contains the number ofquantitative as that is not a bad idea. It is true that somereference to the maximum allowable error or relative that themaximum allowable error of measuring instruments, precisioninstruments and the level of the maximum allowable error of a moredirect relationship, such as 0.25, 0.4 spring-loaded pressure gaugeprecision of the maximum allowable Measurement error of ± 0.25% ofthe ceiling and ± 0.4%, 1-grade material testing machine in therange of measurement (range 20% -100%) of the maximum allowableerror of ± 1.0%. It was so sweeping that all of this, there havebeen such as to "the higher standard of accuracy for the accuracyof the equipment was seized 1 / 3" wrong expression. This view isapparently not universal significance, such as F1 for the weightclass, said the accuracy of 1 / 3, and not knowing what it will be.Figures accuracy of the instrument and level of the maximumallowable error does not necessarily correspond directly, such as asubject to the maximum allowable error of ± 4%, according to thesecondary inspection allowed the greatest error of ± 8%. Equivalentto international standards ISO376: 1999 national standard GB / T13634:2000 "testing machine detected by measuring instrumentcalibration," the test is suitable for a standard testing machineDynamometer is defined as a measuring instrument, which Dynamometerkinds of technical indicators higher than the current standardJJG144-1992 Dynamometer test in order 0.3 Dynamometer. This showsthat the accuracy of the grade level is only a symbol, not as avolume.
By the way that can not be used in place of accuracy or precisionaccuracy and precision that only random effects, corresponding withanother term is correct, the system that effect, it contains onlythe accuracy of the random effects and the effects of thesystem.
Second, uncertainty, or the maximum allowable error is the accuracyof quantitative
We are back again, and so do not look at the accuracy and level ofthe concept. Means, such as measuring instruments, in particular,the standard measurement of the actual value of the equipment toexpand the level of uncertainty to the use of instruments such asthe demarcation of the actual value or based on the test /calibration on the outcome of the show amend the use of value;level refers to the value of measuring instruments that allow Thesize of the error grade to grade equipment into the use of directindication that the amendments do not need to.
When the instrument is no division of accuracy and so on do not, orto consider the accuracy, and so do not be quantified, are givendirectly to the actual value of the expanded uncertainty, that is,the higher its test / calibration of measurement uncertainty; whenmeasuring instruments There is no division-level accuracy, orconsidered to be quantified levels of accuracy, given a directindication of its maximum allowable error. This is the so-called"level of accuracy or uncertainty, or the maximum allowableerror."
Some, such as measuring instruments can only be divided by, forexample, piston pressure gauge, standard hardness block; somemeasuring instruments can only be divided by class, such as thetheodolite, Dial; some measuring instruments, such as by not onlydivided, according to the division level, such as the amount ofBlock, the standard battery. Corresponds to the uncertainty or themaximum allowable error for the meaning to the use of measuringinstruments, and so on can do so on accuracy that can be used toamend or real value of that uncertainty; to level the use ofmeasuring instruments can be accurate Degree level that can be usedto allow the greatest error that can be assessed given indicationerror of measurement uncertainty, at this time, the uncertainty ofmeasurement equipment for the user has no direct meaning, but forthat to the test / Calibration of laboratory instruments and theability of the test was / calibration of equipment in line with therequirements of the maximum allowable error to determine thereasonableness.
Therefore, measuring instruments to fill in the "level of accuracyor uncertainty, or the maximum allowable error," there aredifferent options to fill in one, two or three.
1. In the level of accuracy the existence of the premise, just fillin the level of accuracy is the most simple and clear. Themulti-parameter test and measurement equipment divisions, such asthe theodolite, the sound level meter, fill in the level ofaccuracy is the most appropriate. The use of such instruments, themeasures must be registered, and other technical documents in orderto identify the accuracy level corresponding to the uncertainty orthe maximum allowable error.
2. With the maximum allowable error, said, with the relative erroror error cited that the apparatus, its biggest allow a whole rangeof error in general are the same; with absolute error for thatinstrument, the entire range of its maximum allowable error isdifferent, In this way, can only be given measurement instrumentscorresponds to the upper and lower limits of permissible error. Theuse of such instruments, not to do as a result, the equipmentbrought by the uncertainty is the main instrument that caused theerror. Therefore, the maximum allowable error corresponds to theequipment used by the accuracy of the instrument usually can beassumed that the value of the maximum allowable error in the errorrange of uniform distribution of the equipment brought by theuncertainty of the calculation.
3. For the use of the actual value or indication error on the basisof instructions to carry out amendments to the value of theinstrument, he must make a real uncertainty. As the amendment tothe use of such equipment, apparatus, brought about by theuncertainty is the main instrument for testing / calibration of themeasurement uncertainty. Therefore, the uncertainty of parameterson the accuracy of the use of equipment is the most directimpact.
The calibration laboratory to carry out the project, notnecessarily because the calibration to determine compliance, whenmeasurement uncertainty into the laboratory capacity to measure andcompare the only targets. Fill out the uncertainty of measurementthat the calibration measurement capability, it is necessary, butthe calibration measurement capability is not simply a test doesnot include objects from the introduction of the uncertainty of themeasurement uncertainty. Measurement Uncertainty is measuredagainst the results of evaluation, the dismemberment of theirsimple and crude, both in theory and practice will not work. GUM,such as in comparative law on the gauge block calibration of themost classic example of one of the component is based on the amountby multiplying the length of the block by block traffic school andreference temperature coefficient of sensitivity for the deviation,and then be multiplied by the amount of school block with thestandard gauge block between the thermal expansion Coefficient ofthe poor standard uncertainty; the other component is based on theamount by multiplying the length of the block standard gauge blockcoefficient of thermal expansion coefficient of sensitivity, havebeen multiplied by the amount of school blocks and standard gaugeblock temperature difference between the standard uncertainty. Hasbeen classified / calibration target and the uncertainty of therelationship between shear is a constant, the test / calibrationtarget for the uncertainty of the calculation can not be ruled out,but the measured object can be calculated in a normal state of theleast affected, At this time is calibrated measurementcapability.
The test, based on the test due to the work order, the uncertaintyof measurement is not necessarily beyond a reasonable control, fillout the uncertainty of measurement is a system that can meet thetest requirements.
In addition, the test is relatively simple system, in addition tothe benchmark standards for appliances may be only one level, thework of the apparatus may be only one level, such as metal Brinellhardness tester, with the benchmark countries (including thenational benchmark, vice benchmark, the work of the base) Standardhardness test blocks, and then the hardness standard test block thework of hardness, the standard block and hardness, respectively,and so there is only one other level and, as the standard block ofhardness measurement uncertainty and the maximum allowable hardnessand the pressure error in the first test Power, and so on, can onlygive a range, to express a complex and inconvenient, this is thecase, as long as it does not cause confusion, the hardness of theblock-level accuracy can be "standard level," said the hardnesslevel of accuracy Available "class" that do not have to fill outand the hardness of the block as well as the uncertainty of thehardness of the maximum allowable error.
Therefore, indicators of uncertainty of measuring instruments inlegal metrology body measurement standards assessment, evaluationagencies, recognized laboratory in the meaning should be unified,although there are different priorities.