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HOKLAS Supplementary Criteria No. 2
All Test Categories Equipment Calibration and Verification
1 Introduction
1.1 The HOKLAS criteria on calibration and traceability for non-medical laboratories
stated in Sections 5.5 and 5.6 of HOKLAS 003 and on calibration for medical
laboratories stated in Section 5.3 of HOKLAS 015 apply to all laboratory
equipment. All equipment used for tests and/or calibrations, including equipment
for subsidiary measurement having a significant effect on the accuracy or validity
of the result of the test, calibration or sampling shall be calibrated. This document
sets out the requirements and recommendations for calibration requirements and
calibration intervals for selected types of equipment in Appendices C to I as
follows :-
Appendix C provides general calibration requirements for common equipment
applicable to all Test Categories. Where specific requirements are
given in Appendices D, E, F, G, H and I for specific test areas of
testing or measurement, those requirements should take precedence.
Appendix D covers calibration of standards of measurement and instrumentation
applicable to electrical and electronic testing.
Appendix E covers equipment relevant to engineering metrology.
Appendix F covers calibration using comparative techniques, of analytical
instruments used predominantly in chemical testing laboratories.
Appendix G covers equipment and calibration requirements applicable to
construction materials testing.
Appendix H covers calibration requirements of toy testing equipment.
Appendix I covers calibration requirements for electrical and electronic product
testing
Appendix J covers calibration, performance check and preventive maintenance
requirements for common medical testing equipment
For equipment not included in the above appendices and equipment peculiar to
particular test methods, this document explains how the calibration requirements
and calibration intervals should be determined.
1.2 General recommendations for determining calibration programmes and operation ofthe calibration systems are given in Section 5.
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1.3 This document also explains the available sources of calibration.
2 Calibration Requirements
2.1 Parameters of equipment to be calibrated
Where the values of parameters are specified in the relevant standard specifications,
they shall be calibrated. Where tolerances are given, the measured values should
be checked against them. Where tolerances are not specified, the requirements
given in section 3 of this document should be followed.
2.2 Calibration procedures and intervals
Where the standard specifications state the calibration procedures and the
calibration intervals, these shall be followed.
Where they are not specified, the laboratory should determine appropriate
calibration procedures and intervals after considering all relevant factors. For
dimensions and weights, a period of six months is generally acceptable. Section 5
gives more detailed recommendations for determining calibration programmes.
2.3 Unspecified parameters
For parameters which may affect equipment operation but are not specified, theeffects of change (for example, due to wear) should be assessed during regular
equipment inspection and functional checks. Where necessary, specific
procedures should be derived to assess the effects. It is a good practice to record
initial values as a reference for later comparison.
2.4 All equipment calibrations should be recorded.
3 Parameters With No Stated Tolerance
3.1 Where the tolerances of specified parameters are not given, the laboratory shoulddetermine whether the parameters are critical and how critical they are.
3.2 For critical parameters, justification for adopting particular tolerances should be
documented and HOKLAS will examine them during assessments.
For dimensional and angular measurements, a laboratory may select from
ISO 2768-1: 1989 a suitable tolerance class. As a rough guide, the medium
tolerance class in Table 1 and Table 3, for dimensional and angular measurements
respectively, is acceptable for most equipment.
3.3 In the case of non-critical dimensions, HOKLAS will normally accept that theimplied tolerance is that the next significant figure should not result in rounding to
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a value other than the stated dimension. For example :-
stated parameter implied tolerance6 mm
3.2 mm
1.0 kg
1.000 kg
6 mm 0.5 mm
3.2 mm 0.05 mm
1.0 kg 0.05 kg
1.000 kg 0.0005 kg
4 Source of Calibration
4.1 If calibration of equipment is required, there are two choices :-(a) internal calibration; or
(b) external calibration.
4.2 HOKLAS encourages laboratories to develop their internal calibration capability
and to calibrate their own equipment. A calibration can be performed internally if
the laboratory has the necessary reference standards and materials and the
laboratory staff are competent to perform the calibration. Internal calibration
procedures should be documented.
4.3 Calibrations which require equipment not available to the laboratory or demand
specialist techniques outside the capabilities and experience of the laboratory staff
(see HOKLAS 003, Clause 5.6.H (d)) should be performed externally.
4.4 External calibration shall be performed by a competent calibration body defined in
HOKLAS 003. A laboratory should take the following approaches to find a
competent calibration body :-
(a) Check the HOKLAS Directory of Accredited Laboratories (the up-to-date
scope of accreditation can be found from the HOKLAS internet website at
http://www.itc.gov.hk/en/quality/hkas/hoklas/directory/directory.htm) to see if
a laboratory is accredited for the calibration.
(b) Contact HKSAR Standards and Calibration Laboratory to see if they can
perform the calibration.
(c) Contact HOKLAS calibration Mutual Recognition Agreement (MRA) partners
to see if there is a laboratory which can perform the calibration accredited by
them.
(d) Contact nominated primary standard institutions listed in HOKLAS internet
website at
http://www.itc.gov.hk/en/doc/quality/hkas/supplementary%20criteria/SC2-Ap
pendixB.pdfto see if they can perform the calibration.
HKAS Executive should be consulted if no suitable calibration laboratory could be
found using the above approaches.
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5 Calibration Programme and Operation of Calibration System
5.1 Determination of calibration programmes
The calibration programme applicable to an individual laboratory should be
determined by the laboratory management with due regard to the following factors:
(a) Which items of equipment can be calibrated internally and the interval
between recalibrations.
(b) Which items of equipment need to be calibrated by a competent calibration
body (refer to HOKLAS 003, Section 5.6.H) and the interval betweenrecalibrations.
(c) For each item of equipment, what ranges and cardinal points should be
calibrated, the calibration uncertainty requirements and the conditions under
which calibrations should be performed. These should be determined based
on the requirements of the tests or measurements for which that item of
equipment is being used. Laboratories should document such requirements
and provide them to external calibration laboratories when soliciting
calibration services.
(d) When determining the recalibration intervals, the following should be takeninto consideration:
- HOKLAS recommendations;
- manufacturer recommendations;
- frequency of use;
- equipment condition;
- equipment stability and previous calibration and maintenance history;
- the accuracy and precision requirements of the tests for which that item of
equipment is being used (Where the standard specification states the
calibration intervals, these should be followed);
- the likely influence of the working environment, e.g. corrosion, dust,
vibration, frequent transportation and rough handling;- the availability and reliability of in-service verifications and functional
checks, e.g. the availability of equipment, reference standards or materials
and expertise for conducting in-service verifications and functional
checks (Where in-service checks are not carried out between calibrations,
the calibration interval must be shortened).
For new test instruments, it is advisable to specify a shorter recalibration interval.
When successive calibration results demonstrate that the characteristic of an
instrument is stable, its recalibration interval may be extended. To facilitate the
determination of calibration intervals, laboratories are recommended to plot curves
of instrument drifts against time.
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For more information for determination of equipment recalibration intervals, please
refer to OIML International Document No. 10.
The calibration programme should be documented and reviewed regularly.
5.2 Designated officers of the laboratory shall be assigned the responsibility for the
calibration of equipment and the management of reference materials. Laboratories
should operate a system to alert staff of calibration or verification due dates for all
items of equipment and reference materials. There should also be a mechanism to
ensure that equipment or reference materials due for recalibrations can be released
promptly from routine operation.
5.3 Equipment overdue for calibration should generally be taken out of serviceimmediately. Under exceptional circumstances, the laboratory management may
consider temporarily extending the equipment calibration validity for a short period
of time. Extension of calibration validity should only be allowed when the
equipment calibration history shows that the drift of the instrument is acceptable
and in-service verifications and functional checks demonstrate that the instrument
is functioning normally in every aspect. Nevertheless, the measurement
uncertainty of the instrument may have to be increased according to the drift trend.
5.4 Calibrations should be conducted according to the calibration requirements as
explained in 5.1(c). Where an external calibration laboratory or a different section
of the same laboratory is contracted to perform the calibration, they should beclearly and unambiguously informed of the calibration requirements. These
requirements would generally include the calibration range, the cardinal points, the
required calibration uncertainties and the conditions under which calibrations are to
be performed. It is recommended that a copy of the documented calibration
requirements be provided to the calibration laboratory accompanying the
instrument to be calibrated.
5.5 After an instrument is calibrated, the laboratory should assign a staff member to
check whether the characteristics of the instrument as shown by the calibration
results are still within the acceptable tolerance range. Out of tolerance instruments
should be repaired and recalibrated before use. Alternatively, such instrumentsmay be downgraded for less demanding purposes provided that they are
appropriately labelled.
5.6 The suitability of the calibration programme and the adequacy of the calibration
system will be examined and discussed during assessments.
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6. Address
6.1 Addresses of the various HOKLAS calibration MRA partners and their nominatedprimary standards institutions can be found from the HKAS website at
(http://www.itc.gov.hk/en/quality/hkas/hoklas/agreement.htm).
HKAS Executive
Issue Date: 30 November 2005
Implementation Date: 1 June 2006
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APPENDIX A
ACCREDITATION BODIES WHICH HAVE MUTUAL RECOGNITION
AGREEMENTS WITH HOKLAS ON CALIBRATION
Please refer to the website http://www.itc.gov.hk/en/quality/hkas/hoklas/agreement.htm for
up-to-date information.
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APPENDIX B
ADDRESSES OF NOMINATED PRIMARY STANDARDS INSTITUTIONS
Please refer to the website
http://www.itc.gov.hk/en/doc/quality/hkas/supplementary%20criteria/SC2-AppendixB.pdf
for up-to-date information.
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APPENDIX C
CALIBRATION AND PERFORMANCE CHECK REQUIREMENTS - GENERAL
This Appendix lists the current recommended calibration requirements for specific items of
equipment. These are general recommendations applicable to all Test Categories for which
a laboratory is accredited.
Where specific requirements are given in Appendices D, E, F, G, H, I and J for specific areas
of testing or measurement, those requirements should take precedence.
Type of equipment
Recommended maximum period
between successive calibrations
Calibration procedure or
guidance documents andequipment requirements
ACCELEROMETERS
(i) Reference(ii) Working
Five years (check annually)Two years
ACOUSTIC CALIBRATORS One year
Intercompare every six months
ANEMOMETERS Two years
AUTOCLAVES Initial (on-commissioning) and after
significant repair*Monthly check*
Each use*
Each month*
Every 6 months*
Temperature measurement at
strategic sitesEffectiveness of sterilisation (withbiological indicators)Pressure
Timer accuracy
Heating profiles of typical loads
Effectiveness of sterilization bysuitable means such as chemical
indicators, temperature and timerecord
Effectiveness of sterilisation (withbiological indicators)
Temperature controller calibrationTimer accuracy
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents andequipment requirements
BALANCES and SCALES Three years
orThree years*
Both alternative accompanied by
(i) Each weighing*,(ii) Daily*, and
(iii) Six months*
By a competent calibration bodyas defined in clause 5.6.H (d) ofHOKLAS 003
Calibrate using calibrated masses.Refer The Calibration of Weightsand Balances published by
CSIRO
(i) zero check(ii) one-point check using a
known mass.(iii) repeatability check.
BAND PASS FILTER SETS Two years
BAROMETERS (Fortin) Five years (cleanness of mercury,vacuum space and one-point)
BEAT FREQUENCY
OSCILLATORS
One year
CALIBRATION BATHS
AND FURNACES
Initial complete temperature survey.Check temperature distribution at
one temperature every five yearsCALIBRATION UNIT FOR
AUDIO-FREQUENCYVOLTMETERS
Check annually. Calibrate the
ac/dc transfer error of thermalelement and multiplier every fiveyears
CENTRIFUGES One year (where operating speedspecified)*
Tachometer (mechanicalstroboscope or light cell type)
Temperature calibration (where
applicable)
DENSITY BOTTLES,
PYCNOMETERS
One year* AS 2378; BS 733 App A; IP 190
DENSITY METERS Initial and whenever testtemperature is changed, thereafter*One week checks with air anddouble distilled water*
ASTM D4052
DIAL GAUGES Two years or less, depending onuse*
AS 2103; BS 907
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents andequipment requirements
DIES AND CUTTERSFor preparation of test specimenssuch as dumb-bell rubber specimens
Frequent examination for damage.Full dimensional check whenever
resharpened
EXTENSOMETERS
(a) Level and mirror types
(b) Micrometer screw types
(c) Dial indicator types
(d) Recording types with electricaloutput
Five years
Five years
Two years
Two years
AS 1545 Grade D (for proof stresstests load-extension curves for
pre-stressing wires)
AS 1545 Grade B (for modulus ofelasticity determinations)(BS EN 10002-4)
FLOWMETERS
(a) Rotameters (Reference)High flow,i.e. greater than 1 L/minLow flow,i.e. less than 1 L/min
Two years*
Two years*
ASTMD3195
Soap bubble flowmeter
(b) Rotameters (Working) Each time on use* Soap bubble flowmeter
(c) Orifice plates,Venturi nozzles
(d) Wet test meters
(e) Anemometers
(f) Pitot tubes
Initial
Six months*
One year*
Two years
Initial*On use*
BS 1042: Section 1.2: 1989ISO 5167-1: 1991ISO 9300: 1990
Visual inspect tip and other parts for
damage, wear or contamination
ASTM D1071
Check dimensional compliance withBS 1402 Sec. 2.1 Annex A
Inspect tip for damage, blockage,etc., as requested by BS 1042 Sec.2.1
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents andequipment requirements
FORCE TESTING MACHINES(tension, compression, universal)
TYPE 1 - Mechanical ForceMeasuring Systems
(a) Dead weight(b) Knife edge, lever and
steelyard(c) Pendulum dynamometer
(d) Elastic dynamometer(e.g. spring, ring with dialgauge)
Note: Chain testing and similarmachines in frequent use
TYPE 2 - Hydraulic or PneumaticForce MeasuringSystems
(a) Mechanical systemincorporating a pneumatic or ahydraulic link, e.g.,
proportional cylinder(b) Bourdon tube or diaphragm
pressure gauge as forceindicator
Five yearsFive years
Two years
Two years
One year
Two years
Six months
AS 2193BS 1610: Part 1BS 1610: Part 3
BS 5214 (rubbers and plastics only)EN 10002-2
(c) Type (b) fitted also with amaster gauge which can be
disconnected during normaltesting
(d) Bourdon tube or diaphragmgauge used only as a nulldetector for a mechanicalsystem
(e) Bourdon tube with electrical
transducer
TYPE 3 - Electrical ForceMeasuring Systems
One year (plus frequent checks byuser of working gauge against
master gauge)
Two years
Two years
Two years
FREQUENCY ANALYSERS(Acoustic Measurements) Five years
FREQUENCY RESPONSETRACERS(Acoustic Measurements) Check annually
FREQUENCY STANDARDS(a) For acoustic measurements
(b) For time and frequencymeasurements
Two years
One year
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents andequipment requirements
FURNACESFor use at specified temperatures One Year* BS 4309, AS 2853
GAS STERILISERS Effectiveness of sterilisation.(Regular checks with biologicalindicators at representativelocations in typical loads)*
GAUGE BLOCKS
(a) Used as reference standards
(b) Used as working equipment
Four years
Two years*
BS 4311: Parts 1, 2 & 3
HARDNESS TESTERS FOR
METALS
(a) Brinell, Vickers and Rockwellmachines including portable
testers(b) Portable Brinell microscopes
(c) Diamond indenters
(See Note 1 at end of this
Appendix)
One year (partial)Three years (complete)
One year (with calibrated graticule)
One year (inspection) *
Routine check by user each day fortester in use.
AS 1816 (Brinell)AS 1817 (Vickers)
AS 1815 (Rockwell)
HARDNESS TESTERS FOR
PLASTICS AND EBONITE
(a) Dead weight testers forplastics
(b) Meters (durometer) forrubber
Three years
Frequent checks by user usingreference hardness blocks
ISO 48 : 1994Method N, H, L & M
ISO 7619 : 1997
HYDROMETERS
(a) Reference(b) Working - glass
- metal
InitialOne year against reference or withfreshly prepared solutions of known
density*Six months*
AS 2026; IP 160; ASTM E126
ISO R649
HYGROMETERS
(a) with electric impedance sensor(b) with chilled mirror sensor
Two yearsSix years
IMPACT TESTING MACHINES
(Pendulum type)
(a) Charpy, Izod and Universaltesters for metals
(b) Charpy and Izod testers forplastics
(c) Notching tools
AS 1544.4; BS 131
AS 1146.3
Check regularly and whenever
reground
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents andequipment requirements
IMPEDANCE MATCHINGNETWORKS
(Acoustics measurements)
5 years.Check annually
INCUBATORS and CONSTANT
TEMPERATURE CHAMBER
for BIOCHEMICAL OXYGEN
DEMAND
Every six months against referencethermometer*Constant daily monitoring oftemperature variation duringtesting*
Maximum/minimum thermometersshould also be used to ensuretemperature stays within rangeduring testing.
LENGTH MEASURING
DEVICES
(a) Reference steel rules(b) Working rules and vernier
callipers
InitialMonthly or less depending on use*(zero and general condition)
For making measurements whichwill not affect test results, rules andvernier callipers from reputablemanufacturers may be used without
calibration
LINEAR VARIABLE
DIFFERENTIAL
TRANSDUCERS (LVDTS)
Daily or whenever used*
Two years* (complete calibration)
Check against length standard such
as a micrometer
MANOMETERS(a) Reference
(b) Working
Ten years
Three years*
Check fluid every three years
Check against reference
MICROMETERS One month (zero, one point andcondition of anvils)*
Against gauge blocks. See alsoAS 2102; BS 870 and BS 959
MICROPHONES
(LS1P or LS2P)
Check every three months.
Calibrate annually or when 1 dBchange is detected, whichever is thesooner.
MICROPHONE AMPLIFIERS Check response annually
NEUTRAL DENSITY FILTERS Ten years
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents andequipment requirements
OVENS (Temperature of load spaceshould be monitored by appropriatetemperature sensor throughout use)
(a) Ageing
(b) Drying
(c) Vacuum
Five years (temperature variation,recovery time, rate of ventilation)
Three years (temperature variationand evaporation rate in working
space)*
Five years (temperature variation,evaporation rate, pressure inworking space)*
BS 2648, AS 2853
AS 2853 and AS 1289.0
PENETRATION CONES ANDNEEDLES
Five years ASTM D217; IP 50; ASTM D5;ASTM D1321. Visually inspectneedle tips prior to use.
PHOTOCELLS Check linearity of response everysix months. Check spectralresponse annually with colourfilters; calibrate every five years orwhen apparent filter transmittances
change significantly.
PHOTOMETRIC TEST PLATEFor luminance measurements
Five years
PRESSURE AND VACUUM
GAUGES
(a) Test gauges for calibration of
working gauges(b) Working gauges subject to
shock loading(c) Working gauges not subject
to shock loading
One year
Six months or less depending onuse*One year*
AS 1349; BS 1780: Part 2
PRESSURE GAUGE TESTERS
(a) Dead weight(b) Manometers
Ten yearsTen years
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents andequipment requirements
PROVING DEVICES FORCALIBRATION OF FORCE
TESTING MACHINES
TYPE 1 - Elastic devices(a) Dial gauge for deflection(b) Micrometer screw for
deflection measurement(mechanical or optical
indication)(c) Electrical deflection
measurement
TYPE 2 - Proving levers
TYPE 3 - Weights
Two yearsFive years
Two years
Five years
Ten years
PSYCHROMETERS, ASSMANN
HYGROMETERS and SLING
TYPE PSYCHROMETERS
Ten years (complete)Six months (compare thermometersat room temperature with wickdry)*
AS 2001.1 Appendix C
PYRHELIOMETERS Five years
PYROMETERS
(a) Reference(b) Working
Three yearsSix months*
BS 1041: Part 5
QUARTZ CONTROL PLATES Ten years
RADIOMETERS Calibrate after one hundred tests
REFERENCE BALLASTS Five years
REFERENCE GLASS FILTERS
(a) Spectrophotometry
(b) Colorimetry(d) Luminous transmittance
Five years
Five yearsFive years
REFRACTIVE INDEX
STANDARDS
(a) Liquid(b) Solid
Five years10 measurements or 10 years,whichever is the sooner.
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents andequipment requirements
SIEVES Six months Sieves should comply with theGrade B requirements of AS 1152unless the test method specifies
otherwise.Sieves supplied with a record cardas prescribed in BS 410 areaccepted as complying with
AS 1152 requirements. (SeeAppendix B, AS 1152).
Laboratories requiring more thanone set of sieves should have areference set meeting the aboverequirements and one or moreworking sets.Working sieves should be given a
performance check against thereference set using material typicalof the samples normally subjectedto sieve analysis in the laboratory.
SOUND LEVEL METERS One year
Check every three months*
SOUND POWER SOURCES Five years
STANDARD LAMPSLuminous flux, luminous intensity,illuminance, spectral radiance,spectral irradiance
Five years or after each 20-hourperiod of burning
STOPWATCHES(timers)
Three months* Comparisons against time andfrequency broadcasts fromshort-wave stations such as JJY
(Japan) at 2.5, 5, 8, 10, and 15 MHzfor at least ten minutes.Comparisons against timing signalsbroadcasted by Radio TelevisionHong Kong is also acceptable.
TACHOMETERS
(a) Reference(b) Working
Five yearsOne year*
BS 3403
TAPE RECORDERS(for Acoustic Measurements)
Five yearsCheck annually*
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents andequipment requirements
THERMOHYGROGRAPHS One week against calibratedhygrometer or psychrometer whenused to determine actual RH and
temperature*One month against calibratedhygrometer or psychrometer whenused only as indicator of RH and
temperature variations*
AS 2001.1 Appendices C & D
THERMOCOUPLES
(a) Reference(Preferably noble metal type)
Three years (complete)Six months (one-point)*
BS 1041: Part 4; BS EN 60584-1;ASTM E220; ASTM E230
(b) Working In general, same as for referencethermocouples. Working
thermocouples subject to frequentstress and strain should be checkedmore frequently depending on theirphysical condition and theinhomogeneity effect.
Thermocouples used in hightemperatures have definite life
spans that must be taken intoconsideration.
THERMOMETERS
(a) Liquid-in-glass
(1) Reference
(2) Working
(b) Electronic
(c) Platinum resistance
(d) A.C. resistance bridge
Ten years (complete)Six months (zero-point)*Initial check at sufficient points tocover the expected working rangefollowed by single-point checks at
six-monthly intervals*
Three years (complete)Six months (one-point)*Ten years (complete)Check ice-point before use or at
least every 6 monthsFive years (resistance ratios)
NML Technical Papers No. 1 and 5;ASTM E77Check against a calibrated referencethermometer; NML TechnicalPapers No. 1 and 5;
IANZ Technical Guide No. 3NML Technical Paper No. 5
THICKNESS GAUGES(for compressible materials) Two years Dial gauge, dimensions and
pressure of plunger base
VELOCITY TRANSDUCERS Calibrate sensitivity and frequencyresponse every two years.
Check every six months*
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents andequipment requirements
VISCOMETERS
(a) U-tube
(1) Reference(2) Working
Ten years (against standard oils) *Two years (using quality oil againstreference tubes or standard oils)*
ASTM D2162; BS 4708ASTM D2162/D445; IP 71
(b) Others
(1) Brookfield
(2) Ferranti(3) Zahn
Two years (using standard oils) plusone-months checks using
manufacturers oils, covering thenormal range of operation of theinstrument*Three months (using standard oils)*One year (using standard oils)*
ASTM D2556
VOLUMETRIC APPARATUS
(a) Volumetric glassware(pipettes, burettes, volumetricflasks, distillation receivers)when used for tests where the
error contribution fromglassware to the overallaccuracy required is significantor where methods specifyglassware meeting nominatedstandards.
(b) Specialised glassware (watertraps, sulphonation flasks,centrifuge tubes, etc.)
(c) Piston operated volumetricapparatus (micropipettes)
Initial (on commissioning)*
Initial*
Initial*3 months*
AS 2162.1; BS 1797; BS 6696;ISO 4787
AS 2162.1; BS 1797
Check volume delivered. Foradjustable devices check volume
delivered at several settings (refer toAS 2162.2, ISO 8655 Parts 1-6)
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Items marked * in the table are those which can be carried out by the staff of a laboratory if it is suitably
equipped and the staff is competent to perform such calibrations.
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents andequipment requirements
WEIGHTS(a) Reference weights of integral
construction, stainless steel or
nickel chromium alloy
Five years initial;Ten years subsequent
ASTM E617
(b) Working weights, Class B,stainless steel or nickel
chromium alloy
Three years* ASTM E617
(c) Working weights, Class B, notstainless steel or nickelchromium alloy
One year*
Note: weights used for routine calibration of balance are considered working weights.
NOTE 1 - ADDITIONAL REQUIREMENTS FOR HARDNESS TESTING ON METALS
(1) Laboratories shall carry out a performance check test at the start of each day on which
hardness tests are to be performed.
(2) Hardness blocks with assigned values from established block manufacturers (such as Vickers,
Avery, Wilson and Yamamoto) may be used.
(3) The check should be carried out using forces close to those involved in the tests to be
conducted on that day. So far as is practicable, the hardness values should also match those
involved on that day. Laboratories shall have an adequate range of blocks to cover the range
of hardness and the forces normally encountered.
(4) Laboratories are encouraged to have an accredited metrology laboratory do a limited
calibration on their blocks at the forces applied in the laboratory but which are not included in
their original calibration, but it is recognised that in practice there will be occasions when a
laboratory has to use a force for which the block has not been calibrated.
(5) For Vickers and Rockwell hardness tests, laboratories may use uncalibrated indenters,
provided those indenters have been checked by performance tests on hardness blocks withassigned values and by inspection at a magnification of a least 50x.
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APPENDIX D
CALIBRATION REQUIREMENTS FOR ELECTRICAL AND ELECTRONIC
MEASURING EQUIPMENT
The following table sets out recommended maximum periods between successive calibrations
for a number of reference standards and measuring instruments. It must be stressed that
these periods are generally considered to be the maximum appropriate in each case providing
that the other criteria as specified below are met :-
that the equipment is of good quality and of proven adequate stability, and
that the laboratory has both the equipment capability and staff expertise to performadequate internal checks, and
that if any suspicion or indication of overloading or mishandling arises, the
equipment will be checked immediately and thereafter at fairly frequent intervals
until it can be shown that stability has not been impaired.
Where the above criteria cannot be met, appropriately shorter intervals may be specified.
The nominal maximum period may be extended in special cases where the laboratory has
demonstrated exceptional self-checking capability or successful participation in proficiency
testing programmes involving portable standards.
Type of equipmentRecommended maximum period
between successive calibrations
ATTENUATORS Three years (frequency response)
BRIDGES Five years (full calibration)Check against laboratory standard annually
CAPACITORS Five yearsIntercompare annually
DIGITAL METERS One year
INDUCTORS Five yearsIntercompare annually
INSTRUMENTS, INDICATING
AND RECORDING
Five years
Intercompare every six months, or more frequently as required
INSTRUMENT and RATIO
TRANSFORMERS
Ten years
INSTRUMENT TRANSFORMER TEST
SETS
Five years (full calibration)
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Type of equipmentRecommended maximum period
between successive calibrations
POTENTIOMETERS Five years
RESISTORS Five yearsIntercompare annually
RF POWER MEASURING EQUIPMENT Three years
SIGNAL GENERATORS One year (frequency accuracy, output level and attenuatorratio)
STANDARD CELLS Two yearsIntercompare at least six-monthly
TIME, TIME INTERVAL and
FREQUENCY STANDARDS
Calibration intervals dependent on equipment frequency, typeand accuracy required. This may be as frequently as daily ifthe highest possible performance is required.
TRANSFER STANDARDS, AC-DC Eight yearsIntercompare immediately after calibration and then every four
years
VOLTAGE CALIBRATING
TRANSFORMERS
Ten years
VOLT RATIO BOXES Five yearsIntercompare annually
WATTHOUR METERS
(ELECTRO-MECHANICAL)
Two yearsIntercompare every three months
WATTMETERS AND WATTHOUR
METERS (ELECTRONIC)
One year with regular intercomparisons - interval to be basedon history of performance
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APPENDIX E
CALIBRATION REQUIREMENTS FOR ENGINEERING METROLOGY
INSTRUMENTS
The following table sets out the maximum recommended period between initial calibration
and the first recalibration, and the maximum period between subsequent recalibrations
provided that the first two calibrations indicate that the item is stable. The recalibration
interval for each specific item will be examined during the assessments of the laboratory.
Account will be taken of factors such as general condition and frequency of use.
Item
Maximum period between
initial calibration and thefirst recalibration (years)
Maximum period between
subsequent recalibrations(years)
ANGLE GAUGES(a) reference(b) working
42
84
DIVIDING HEADS 5 8
GAUGE BLOCKS(a) reference
(b) working
4
2
8
4
HEIGHT SETTING MICROMETERS AND
RISER BLOCKS
3 3
LENGTH BARS(a) reference(b) working
42
84
LEVELS (precision) 4 4
LINEAR (precision) 5 10
OPTICAL FLATS 3 6
OPTICAL PARALLELS 3 6
PRECISION POLYGONS 5 10
ROLLERS AND BALLS 4 8
ROUNDNESS STANDARDS 5 10
ROUGHNESS STANDARDS 4 4
SCREW CHECK PLUGS FOR RING
GAUGES
3 6
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Item
Maximum period between
initial calibration and thefirst recalibration (years)
Maximum period between
subsequent recalibrations(years)
SCREW PITCH REFERENCE STANDARDS
3 6
SETTING CYLINDERS 3 6
SETTING RINGS 3 6
SQUARES
trysquares block squares
24
58
SURFACE PLATES cast iron granite
34
58
THREAD MEASUREMENT CYLINDERS 4 6
THREAD MEASUREMENT VEE PIECES 2 5
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APPENDIX F
CALIBRATION AND PERFORMANCE CHECKS REQUIREMENTS FOR
ANALYTICAL INSTRUMENTS FOR CHEMICAL TESTING
1. Introduction
1.1 Analytical instruments used in chemical testing are frequently calibrated by comparative
techniques, that is, the response signals of the instrument are related to the
concentrations or amounts of the analyte through the use of reference materials. Many
types of analytical instruments require calibration before use and calibration thus forms
an integral part of the analytical procedures.
1.2 Correct use combined with proper calibration may not necessarily ensure an instrument
is performing adequately. Where appropriate, periodic checks on the performance
characteristics should be carried out. These instrument performance characteristics
include, for example, response, stability and linearity of sources, sensors and detectors,
the separation efficiency of chromatographic systems, the alignment and wavelength
accuracy of spectrometers, etc. The purpose of these checks is to verify the performance
of the instruments against the specified requirements of the tests for which the
instruments are being used.
1.3 This Appendix sets out specific calibration and performance checks requirements for
analytical instruments used for chemical testing. Laboratories should refer to Sections
5.5 and 5.6 of HOKLAS 003 and other sections of this supplementary criteria for
general requirements on calibration of equipment. Equipment in common with other
testing fields are listed in Appendix C.
1.4 The laboratory should document and implement a calibration and/or performance checks
programme appropriate to the circumstances involved. The performance characteristics
to be checked as well as the acceptance criteria for and frequency of checks should be
based on the requirements of the tests concerned taking into consideration the
recommendations given in Table 1 and factors given in clause 3.1 of this appendix. It is
the responsibility of the laboratory to demonstrate that the programme is suitable for thecircumstances involved.
1.5 Since standard practice for operation of analytical instruments are generally unavailable
or highly specific to a particular application, the laboratory shall document its practice
for use of analytical instruments. This should include, as appropriate, a description of the
operation of the instrument, procedures and acceptance criteria for calibration and
performance checks, frequency of use and nature of quality control samples, and
maintenance procedures.
1.6 Calibration and performance checks can normally be conducted by the staff of a
laboratory. The laboratory should, however, ensure that sufficient reference materialsand required equipment are available, and the persons involved should possess the
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required skills, experience and training.
1.7 The laboratory shall ensure that all calibration and/or verification of analyticalinstruments are traceable to national or international standards of measurement or to
reference materials produced by competent producers (see HOKLAS Supplementary
Criteria No. 1).
2. Calibration
2.1 Normally, either the manufacturers of the instruments and/or the test standards
themselves specify the calibration procedures and requirements. These instructions
should be followed, if available. In some cases, check samples are used during analyses
to confirm the validity of the calibration. Re-calibration of instruments should be carriedout when such checking procedure indicates that previous calibrations are no longer
valid.
2.2 Acceptance criteria for calibration and criteria for re-calibration should be based on the
test standards, if available, or determined by the requirements of the tests concerned.
These criteria shall be documented and strictly adhered to.
2.3 Acceptance criteria for calibration should include a criterion for the acceptability of the
calibration function and, when applicable, a criterion for the performance of instruments.
An example of the former criterion is correlation coefficient of a linear calibration graph
whilst the latter may include, for example, the slope of the calibration graph or themagnitude of the detector response at a specific level of analyte. The latter instrument
performance check (IPC) during calibration should not be confused with that described
in Clause 3 below. This IPC should be regarded as a routine start-up check on the
usability of instruments as distinguished from the verification of equipment against
requirements of tests.
3. Performance check
3.1 It is inappropriate to specify a rigid frequency for performance checks since the
frequency depends on a number of factors including :-- type of equipment;
- manufacturers recommendation;
- trend data obtained from previous performance checks records;
- recorded history of maintenance and servicing;
- extent and severity of use;
- tendency to wear and drift;
- frequency of cross-checking against other reference standards;
- environmental conditions (temperature, humidity, vibration, etc.);
- accuracy and permissible limits of errors.
3.2 Acceptance criteria for performance checks should be based on the requirements of test
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standards, if available, taking into consideration recommendations given by the
manufacturers of the instruments. Test standards may sometimes explicitly state the
acceptance criteria for various performance characteristics but, frequently, suchacceptance criteria have to be derived from the requirements of test standards. For
instance, the detection limits of an instrument may have to be derived from the
specification limits of the standards.
3.3 Instruments shall be taken out of service when results of performance checks fall outside
the acceptance criteria. Suitable corrective measures and servicing should be taken when
results of performance checks indicate that there is a system degeneration. An
instrument should not be put back into service unless subsequent checks indicate that its
performance fulfils the acceptance criteria.
3.4 The performance characteristics to be checked depends on the type of the instrument.Table 1 lists those performance characteristics of common analytical instruments that
require to be checked.
4. Calibration and Performance Check Frequency
4.1 Table 1 sets out the normal frequencies for calibrations and performance checks of
common analytical instruments. The frequencies, when given, are recommended
maximum periods. They serve as a starting point for initial selection of
re-calibration/performance checks intervals.
4.2 Intervals of calibration/performance checks should be reviewed regularly and
adjustments of these intervals may be made based on experience. However, any revision
of frequency shall be justified (e.g. changes of usage, environment, required accuracy,
etc.). The guidelines given in OIML International Document No 10 for the
determination of recalibration period should be followed.
4.3 Test standards may sometimes specify a shorter calibration/performance check intervals
than that listed in Table 1. In such cases, the frequency recommended by the test
standards shall be followed. In addition, if major mechanical or electronic maintenance
is carried out, the appropriate checks should be conducted when the instrument is
re-commissioned.
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Table 1 Calibration and Performance Checks Requirements
for Analytical Instruments
Type of equipmentRecommended period between
successive calibrations
Calibration procedure or guidance
documents and equipment
requirements
BOMB CALORIMETERS 6 months or after any significantpart of the system has been changed
Determine the effective heat capacityusing certified benzoic acid. Referto ISO1928.
CONDUCTIVITY METERS 6 months Determine cell constant usingpotassium chloride standard
solutions appropriate to each desiredmeasuring range. Refer to ISO7888/OIML R56 & 68.
DISSOLVED OXYGEN
METERS
Calibrate before useCheck linearity before using theinstrument for routine purposes andmonthly thereafter
Calibrate at zero and a value nearsaturation. Check linearity. Refer toISO 5814.
pH METERS Calibrate on useCheck performance for new
electrodes, and once every 2 weeksthereafter
Calibrate the instrument with twostandard buffers on use, appropriate
to the anticipated pH of the samplebeing measured. Check performancecharacteristics such as liquid junction
error, shift on stirring and noise.Refer to ISO 10523.
TURBIDIMETERS Calibrate on use Calibrate the apparatus using
formazine standard solutions. Atleast five points with each measuringrange should be used for plotting thecalibration graph. Refer to ISO 7027.
CHROMATOGRAPHS Calibrate on use. Checkperformance yearly
(a) Gas chromatographs check thefollowing, as appropriate:
i. Overall system checks,
precision of repeat sampleinjections, carry-over;
ii. Column performance(capacity, resolution,retention);
iii. Detector performance(detection limit and
linearity);iv. System heating/
thermostatting (accuracy,precision, stability, rampingcharacteristics);
v. Autosampler (accuracy and
precision of time routines).Refer to OIML R82/83/113
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Type of equipmentRecommended period between
successive calibrations
Calibration procedure or guidance
documents and equipment
requirements
CHROMATOGRAPHS(contd)
Calibrate on use. Checkperformance yearly
(b) Liquid chromatographs checkthe following, as appropriate :
i. Overall system performance;ii. Detector sensitivity;iii Mobile phase delivery system
(precision, accuracy,pulse-free)
Refer to OIML R112.
SPECTROMETERS AND
SPECTROPHOTOMETER
Calibrate on use. Check
performance yearly
(a) UV/Visible - Check wavelength
accuracy, stray radiation,absorbance accuracy and zero
absorbance line flatness. Referto AS3753.
(b) Infra-red - Check wavenumber
accuracy, wavenumberreproducibility and beambalance. Refer to ASTM E932.
(c) Atomic Absorption - Checkprecision, sensitivity and
detection limit of metals ofinterest. Refer to OIML R100.
(d) Atomic Emission usingarc/spark discharge - Checkprecision and background
equivalent concentration. Referto AS 2883.
(e) Inductively Coupled PlasmaAtomic Emission - Checkrepeatability, backgroundequivalent concentration and
detection limit. Refer toAS3641.2/OIML R116.
(f) X- Ray Fluorescence - Checkprecision, counter resolution,dead time. Refer to
AS2563/OIML 123
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Annex I
(Informative)
Bibliography
Part 1 General Principles of Equipment Calibration
Laboratory staff responsible for equipment calibration and verification are strongly advised to
consult the following references.
1. CITAC/EURACHEM Guide 1 International Guide to Quality in Analytical Chemistry.
An Aid to Accreditation.
2. ISO10012 Measurement management systems - requirements for measurement process
and measuring equipment.
3. ISOGuide 32 Calibration in analytical chemistry and use of certified reference
materials.
4. ISOGuide 33 Uses of certified reference materials.
5. ISO/TR 13530 Water quality - Guide to analytical quality control for water analysis.
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Part 2 Recommended Practices for Specific Equipment
The following references contain description of the operation, calibration and/or performancecheck procedures. Operation staff of laboratories are strongly advised to familiarize
themselves with these references.
A. UV/Visible Spectrophotometers
1. AS3753 Recommended practice for chemical analysis by ultraviolet/visible
spectrophotometry.
2. ASTME131 Standard terminology relating to molecular spectroscopy
3. ASTME169 Standard practices for general techniques of ultraviolet quantitative
analysis
4. ASTME275 Standard practice for describing and measuring performance of ultraviolet,
visible and near-infrared spectrophotometers
5. ASTME925 Standard practice for monitoring the calibration of ultraviolet-visible
spectrophotometer whose spectral slit width does not exceed 2 nm
6. ASTME958 Standard practice for measuring practical spectral bandwidth of
ultraviolet-visible spectrophotometers.
B. Infra-red Spectrophotometers
1. ASTME168 Standard practice for general techniques of infrared quantitative analysis
2. ASTME275 Standard practice for describing and measuring performance of ultraviolet,
visible and near-infrared spectrophotometers
3. ASTME932 Standard practice for describing and measuring performance of dispersiveinfrared spectrophotometers
C. Atomic Absorption Spectrophotometers
1. AS2134 Recommended practice for chemical analysis by atomic absorption
spectrometry: AS2134.1 Flame atomic absorption spectrometry, AS2134.2 Graphite
furnace spectrometry and AS2134.3 Vapour generation AAS
2. AS3550.6 Determination of filtrable calcium - Flame atomic absorption spectrometric
method
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3. ASTME1184 Standard practice for electrothermal (graphite furnace) atomic absorption
analysis
4. APHA3111 Metals by flame atomic absorption spectrometry
5. APHA3112 Metals by cold-vapour atomic absorption spectrometry
6. APHA3113 Metals by electrothermal atomic absorption spectrometry
7. APHA3114 Arsenic and selenium by hydride generation/atomic absorption
spectrometry
D. Atomic Emission and X-Ray Fluorescence
1. AS1502 Glossary of terms used in X-ray spectroscopy
2. AS2563 Wavelength dispersive X-ray fluorescence spectrometers - determination of
precision
3. AS2883 Analysis of metals - Procedures for the setting up, calibration and
standardization of atomic emission spectrometers using arc/spark discharge
4. AS3641.1 Recommended practice for atomic emission spectrometric analysis Part 1Principles and techniques
5. ASTME135 Standard terminology relating to analytical chemistry for metals, ores and
related materials
6. ASTME158 Standard practice for fundamental calculations to convert intensities into
concentrations in optical emission spectroscopy analysis
7. ASTMD305 Standard establishing and controlling spectrochemical analytical curves
8. ASTME826 Standard practice for testing homogeneity of materials for the developmentof reference materials
E Inductively Coupled Plasma
1. AS3641.2 Recommended practice for atomic emission spectrometric analysis Part 2
Inductively coupled plasma excitation
2. APHA3120 Metals by plasma emission spectroscopy using inductively coupled plasma
source
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F. Gas and liquid chromatographs
1. AS3741 Recommended practice for chemical analysis by ion-chromatography
2. ASTMD1945 Standard test method for analysis of natural gas by gas chromatography
3. ASTMD4626 Standard practice for calculation of GC response factors
4. ASTME260 Standard practice for packed column chromatography
5. ASTME355 Standard practice for gas chromatography terms and relationships
6. ASTME516 Standard practice for testing thermal conductivity detectors used in gas
chromatography
7. ASTME594 Standard practice for testing flame ionization detectors used in gas or super
critical fluid chromatography
8. ASTME682 Standard practice for liquid chromatography terms and relationships
9. ASTME685 Standard practice for use of fixed wavelength photometric detectors used
in LC
10. ASTME697 Standard practice guide for use of EC detectors in gas chromatography
11. ASTME840 Standard practice guide for use of FP detectors in gas chromatography
12. ASTME958 Standard practice for measuring spectral bandwidth of UV/Vis
spectrophotometers
13. ASTME1151 Standard practice for ion chromatography terms and relationships
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APPENDIX G
CALIBRATION REQUIREMENTS FOR CONSTRUCTION MATERIALS TESTING
EQUIPMENT
This appendix lists the items of equipment and their calibration requirements within the
Construction Materials Test Category in the test areas covering aggregates, bituminous
materials, concrete and steel. Specific calibration requirements for other test areas are
included in other Supplementary Criteria listed as follows:
Supplementary Criteria No. 15 for non-destructive tests of welding
Supplementary Criteria No. 16 for foundation testing
Supplementary Criteria No. 17 for building components and related testing
Supplementary Criteria No. 18 for ground investigation testing and sampling
Supplementary Criteria No. 19 for soil and rock testing
For construction materials testing equipment, the criteria in this appendix should be read first
over any other appendices in this supplementary criteria. Where conflicting criteria exist,
the requirements of this appendix shall take precedence. The calibration periods listed here
are the maximum acceptable, and shorter time periods may be required due to frequency of
use and storage conditions.
Environment
General policy on environment is covered under section 5.3 of HOKLAS 003.
In addition to the comments therein it is possible for an accreditation to be granted for tests
conducted under more than one set of environmental conditions provided that these are :
In accordance with the standard concerned and
The test report indicates clearly which criteria have been adopted.
Equipment
Criteria are contained elsewhere in this Supplementary Criteria in respect of other items
under different Test Categories. Several of the construction materials standards do however
contain details of items of equipment peculiar to the test method concerned. Calibration and
maintenance of these items should generally satisfy one of the following :-
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Where the standard concerned gives a calibration procedure, this procedure shall be
followed and the maximum period between successive calibrations shall be that
specified in the standard.
Where no calibration procedure is given in the standard but tolerances on
dimensions or mass are provided, a check against the specified values shall be
made and recorded at least once every 12 months unless a calibration interval is
given in the standard.
Equipment for which no detailed criteria or tolerances are given should be regularly
inspected.
Solutions
There are many instances where solutions are required in connection with both the physical
and chemical testing of materials.
It is not practical to give detailed guidance on the storage and shelf life of these but
laboratories involved should either;
Make up fresh solutions as and when required, where the standard concerned gives
a calibration procedure but without a calibration interval, the calibration interval
shall be 6 months, or
Initiate a programme for ascertaining the shelf life of the solutions concerned.
In the case of distillation and/or de-ionizing of water, the equipment concerned should be
checked for satisfactory performance at least once every 6 months.
Reference Materials
Reference materials called up in standards shall be obtained from the sources stated in the
standard and stored in the prescribed manner. Specific HOKLAS policy on referencematerials is covered under clause 5.6.H (f) of HOKLAS 003.
Specific HOKLAS Calibration Criteria
The following table sets out the maximum periods between successive calibrations for
equipment to be used in connection with testing of aggregates, bituminous materials, concrete,
steel, and soils within the Construction Materials Test Category. Specific HOKLAS policy
for calibration is covered under section 5.6 and 5.6.H of HOKLAS 003.
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents and equipment
requirements
2 years By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003.
6 months Repeatability check using referencemasses of higher grades.
BALANCE(Reference)
1 month One-point check using reference massesto balance capacity
(a) 3 years or immediately
following servicing
Calibrate using reference masses in
accordance with the national standardmethod or other equivalent standards.
(b) 6 months Repeatability check using referencemasses in accordance with a standard
method. Adjust the balance and carryout a full calibration if the requiredtesting accuracy is exceeded.
(c) Daily before use One-point check using a known mass ator close to a frequently encounteredvalue or the balance capacity for a
specified range.
BALANCE
(Working)
(d) Each weighing Zero check after tare.
CALLIPERS
(Vernier or digital readout)
(Accuracy equal to and betterthan 0.01mm)
2 years By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS
003
(Accuracy between 1 mm and
0.01mm)
1 year Calibrate using reference gauge blocks
or callipers checker. A sufficient
number of readings shall be takencovering the expected working range.
(Accuracy not better than 1mm) Initial only Callipers from reputable manufacturersmay be used.
Callipers of any accuracies Before use Zero check.
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents and equipmentrequirements
DIAL GAUGE
(Accuracy equal to and better
than 0.01mm)
1 year By a competent calibration body as
defined in clause 5.6.H (d) of HOKLAS003
(Accuracy not better than0.01mm)
1 year Calibrate using reference gauge blocksor a micrometer type calibrator forcompliance with BS907 or AS2103.
LINEAR DISPLACEMENT
MEASURING DEVICE
(LVDT, digimatic gauge, Demecgauge or any other transducertypes)
(Accuracy equal to and betterthan 0.01mm)
1 year
Before use
By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003
One-point check using gauge block.
1 year Calibrate the measuring device togetherwith the same readout unit as is used for
test using reference gauge blocks or a
micrometer type calibrator. Thereadout unit can be an electrical displayunit, digital display unit or data logging
system.
(Accuracy not better than0.01mm)
Before use One-point check using gauge block.
MASS(Working-hanger weights)
1 year Calibrate using reference balance.
MICROMETER
(Accuracy equal to and better
than 0.01mm)
2 years By a competent calibration body as
defined in clause 5.6.H (d) of HOKLAS003
(Accuracy not better than0.01mm)
1 year Calibrate using reference gauge blocks.A sufficient number of readings shall betaken covering the expected workingrange.
Micrometer of any accuracies Before Use Zero Check.
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents and equipmentrequirements
OVEN (a) 3 years or immediatelyfollowing servicing or eachchange in temperature setting
Check temperature variation in workingspace using different referencethermocouples at the same time and also
check evaporation rate for compliancewith the requirements of AS 2853 andAS 1289 or other relevant standardmethods.
(b) 6 months Check temperature at centre of usable
oven space inside an empty oven using areference thermocouple. Ten readingsshall be taken at 3-minute intervals with
the oven set at the working temperaturerange.
PRESSURE GAUGECALIBRATOR
(Reference standard)
Dead weight tester 5 years By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003
Manometer 5 years By a competent calibration body as
defined in clause 5.6.H (d) of HOKLAS
003
PRESSURE GAUGE(Reference)(Electrical transducer type)
2 years By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003
PRESSURE GAUGE
(Working gauge)
Bourdon tube or hydraulictype
1 year By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003
Transducers types 1 year By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003
RULE 2 years Check against reference length standardwith a higher accuracy. Check at aminimum of 5 points over the entire
length.
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents and equipmentrequirements
SIEVE
(Reference woven wire cloth
sieves, for performance checkingof test sieves)
Initial only Sieves with recognized manufacturers
certificates which certify conformancewith BS410: 1986 shall be used.Reference sieves shall be downgraded totest sieves after 30 passes.
(Perforated plate test sieves
apertures larger than or equal to4mm)
300 passes but not exceeding 6
months
Check aperture and bridge width using
calibrated callipers, optical projection, orother appropriate devices in accordancewith BS410 : 1986.
(Woven wire cloth test sieves apertures less than 4mm)
300 passes but not exceeding 6months
Check aperture using optical projectionor other appropriate equipment in
accordance with BS410 : 1986.Alternatively, check performance ofapertures using certified referencesamples or performance check sampleswith reference sieves in accordance withBS 812:Part 100: 1990 or BS 1377:Part1:1990. Sieves with manufacturers
certificates which certify conformancewith BS410:1986 may be used directlywithout initial checking.
THERMOCOUPLE(for checking ovens)
3 years By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS
003
6 months One-point check, at ice point or someother appropriate temperature.
THERMOMETER -(Mercury-in-glass)
(Accuracy equal to and betterthan 0.5C)
5 years By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS
003
6 months One-point check, at ice point or someother appropriate temperature.
(Accuracy not better than 0.5C) 5 years Calibrate over the expected workingrange using a reference thermometer and
suitable calibration bath.
6 months One-point check, at ice point or someother appropriate temperature.
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents and equipmentrequirements
THERMOMETER (Electronic, digital and platinumresistance)
3 years By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS
003
6 months One-point check, at ice point or someother appropriate temperature.
TIME MEASURING DEVICE
(a) Accuracy equal to or betterthan 0.5 second
(b) Accuracy not better than 0.5
second
1 year
3 months
Calibrate against reference time standardin accordance with relevant calibration
standard.
Check against time given by radio time
(RTHK) signal for at least half an hour.
VACUUM GAUGE
(a) Mechanical or hydraulic
(b) Transducer
2 years
1 year
By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003
By a competent calibration body as
defined in clause 5.6.H (d) of HOKLAS003
VOLUMETRIC
GLASSWARE(burettes, pipettes, volumetricflasks including measuring
cylinders)
Initial only Check by weighing the amount ofdistilled water that the vessel contains ordelivers at a measured temperature,applying any temperature corrections
necessary using the Tables inBS1797:1987. The mass of water shallbe determined to within 0.01%. Thechecking shall be repeated a sufficientnumber of times to obtain the averagevolume. Where a vessel is to be used at
a particular graduation mark only,checking may be limited to that mark butthe vessel must be labelled to indicateclearly the limited checking.
AGGREGATES
ABRASION MACHINE 1 year Check dimensions of moulds, trays and
plates; speed of rotation of machine andmass of weights in accordance with BS812:Part 113: 1990
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents and equipmentrequirements
ACCELERATED
POLISHING MACHINE
1 year Check rate of flow of flowmeter,rotational speed of rad wheel, planes ofrotation of tyred and road wheels, free
force of rubber wheels, and rubber tyredand road wheel dimensions inaccordance with BS 812:Part 114:1990.
ELONGATION GAUGE 1 year Check with calibrated callipers ormicrometer
FRICTION TESTER 1 year Check dimensions and mass of rubberslider in accordance with BS 812:Part
114:1990.
Before use Check specimen contact angle of rubberslider and verticality of column inaccordance with BS 812:Part 114:1990.
IMPACT TESTING DEVICE 1 year Check dimensions of cylindrical steelcup and metal hammer, mass of circular
metal base and metal hammer, and fallof hammer in accordance with BS812:Part 112: 1990.
THICKNESS GAUGE
(for determination of flakinessindex)
1 year Check with calibrated callipers or
micrometer.
BITUMINOUS MATERIALS
CENTRIFUGE(for extraction of binder)
TACHOMETER
1 year
5 years
Check the operating speeds using acalibrated tachometer
By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS
003
MARSHALL TESTING
MACHINE
(a) Stability load
measurement
6 months By a competent calibration body as
defined in clause 5.6.H (d) of HOKLAS003 in accordance with BS 1610 or BSEN 10002 or other equivalent standards.
(b) Flow displacementmeasurement
1 year Refer to previous section on dial gaugeor linear displacement measuring device.
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents and equipmentrequirements
CONCRETE AND ITS CONSTITUENT MATERIALS
CEMENT FINENESS
TESTING APARATUS
(a) Lea & Nurse 1 year By use of certified reference materialas defined in clause 5.6.H.(f) of
HOKLAS 003.
(b) Rigden or Blaine 3 months By use of certified reference materialas defined in clause 5.6.H.(f) of
HOKLAS 003.
CHLORIDE ION
PENETRATION TESTER
(a) Voltage measuring device 1 year By a competent calibration body as
defined in clause 5.6.H (d) of HOKLAS003 in accordance with a relevant
standard.
(b) Current measuring device
(c) Reagent NaCl and NaOH
1 year
Freshly made
By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003 in accordance with a relevant
standard.
Reagents to be at least analytical grade
COMPACTING FACTOR
APPARATUS
1 year Check compliance with requirement inaccordance with CS1 : 1990.
COMPRESSION TESTING
MACHINE
(a) Load rate 1 month By use of calibrated timing device
against criteria for tests in accordance
with CS1: 1990.
(b) Load verification 6 months or after relocation of the
machine (Note: An additional checkat 3 months shall be performed if
the two previous checks haveindicated a change of machinegrading)
By a competent calibration body as
defined in clause 5.6.H (d) of HOKLAS003 in accordance with BS 1610 or BS
EN 10002 or other equivalent standards.
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents and equipmentrequirements
COMPRESSION TESTING
MACHINE(Contd)
(c) Machine plattens auxiliaryplattens and spacer blocks
(i) Surface condition 1 month Visual inspection check for signs ofwear and damage.
(ii) Flatness, parallelism 1 year Using reference checking devices inaccordance with CS1 : 1990.
(d) Performance 6 months or after relocation of themachine
By a competent calibration body asdefined in the clause 5.6.H (d) of
HOKLAS 003 in accordance with BS1881 or CS1:1990.
(e) Strain cylinders(for checking theperformance of the machine)
2 years By a competent calibration body asdefined in the clause 5.6.H (d) ofHOKLAS 003 in accordance with NIS0409 or BC415
(f) Proving devices(for calibration of force
testing machines)
2 years By a competent calibration body asdefined in the clause 5.6.H (d) of
HOKLAS 003 in accordance with BS1610 or BS EN 10002 or otherequivalent standards.
CREEPTESTINGAPPARATUS(Load verification with aservo-controlled system)
Each test By a competent calibration body asdefined in the clause 5.6.H (d) ofHOKLAS 003
CURING TANK
(CUBE OR OTHER SAMPLE) 6 months
Daily
Check the efficiency of circulation andtemperature distribution at 60%
capacity, with different referencethermometers at minimum 9 points at thesame time.
Check the max/min temperature.
CUBE MOULD
Dimensions, flatness, squarenessand parallelism
6 months Check compliance with requirement inaccordance with CS1 : 1990..
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents and equipmentrequirements
CYLINDER (Reference-check
the cylindricity of concrete
core)
5 years By a competent calibration body asdefined in the clause 5.6.H (d) ofHOKLAS 003 or by means of
appropriate reference devices
FLOW CONE 1 year Check apparatus in accordance withASTM C939 Clause 8 using a referencetime measuring device
FLOW TABLE 1 year Check apparatus in accordance withBS1881:Part 105:clause 3.1
MIST CURING ROOM 6 months
Daily
Check temperature using differentreference thermometers at a minimum of
9 points at the same time or checkmaximum temperature fluctuation using
a reference thermometer at minimum of9 points, and check humidity distributionto ensure no dry surfaces. Compare theeffectiveness with equivalent tank cured
specimens
Check the max/min temperatureCheck wetness of surfaces
PFA FINENESS TESTING
APARATUS(check aperture size of standardsieve)
6 months By use of certified reference materialsas defined in clause 5.6.H.(f) ofHOKLAS 003.
SLUMP
(a) Cone 1 year Check dimensions in accordance withCS1:1990.
1 week Check ovality of base and top to
CS1:1990.
(b) Rod 1 year Check dimensions in accordance withCS1:1990.
STEEL
ANCHOR BOLT PULL OUT
AND PROOF LOAD TESTERLoad verification or forcetransducer
1 year By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003 in accordance with a relevantstandard
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents and equipmentrequirements
BENDING TESTING
MACHINE
(a) Load rate 1 month By use of calibrated timing deviceagainst criteria for tests in accordancewith CS1:1990
(b) Formers 1 month Visual inspection for wear
EPOXY COATED BAR
(a) Coating thickness gauge 1 year By use of reference device in accordance
with relevant standards
(b) Holiday detector 1 year By use of reference device in accordancewith relevant standards
EXTENSOMETER
(for rebars and structural steel) 1 year By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003 in accordance with BS 3846:1970.
EXTENSOMETER(for coupler and strand)
(a) Mechanical type 1 year By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003 in accordance with a relevantstandard.
(b) Optical and transducer types 1 year By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003 in accordance with a relevant
standard.
HARDNESS TESTER
(a) Brinell, Vickers and
Rockwell Machines
1 year By a competent calibration body as
defined in clause 5.6.H (d) of HOKLAS003 in accordance with a relevantstandard.
(b) Indenter 3 years By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003 in accordance with a relevantstandard.
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Type of equipmentRecommended maximum period
between successive calibrations
Calibration procedure or
guidance documents and equipmentrequirements
IMPACT TESTER
Charpy V or U notch
machine
1 year By a competent calibration body as
defined in clause 5.6.H (d) of HOKLAS003 in accordance with a relevantstandard.
TORQUE WRENCH(For checking of power-operated
and hand-operated friction bolts)
1 year By a competent calibration body as
defined in clause 5.6.H (d) of HOKLAS003 in accordance with a relevantstandard
TENSILE TESTING
MACHINE
(a) Load rate 1 month By use of calibrated timing device
against criteria for tests in accordancewith BS 18.
(b) Load verification 6 months or after relocation of themachine (Note: An additional checkat 3 months shall be performed iftwo previous checks have indicated
a change of machine grading.1 month)
By a competent calibration body asdefined in clause 5.6.H (d) of HOKLAS003 in accordance with relevantstandards.
(c) Specimen gaugingequipment
Spot check on prepared samples.
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APPENDIX H
CALIBRATION REQUIREMENTS FOR SELECTED PHYSICAL AND
MECHANICAL TOY TESTING EQUIPMENT
The general principles in Appendix C apply to common equipment such as thermometers,
balances, mass, thermohygrographs, stopwatches, pressure gauges, ovens, vernier callipers,
micrometers, glassware, rules, furnaces, etc. For chemical testing, the general principles for
the use of analytical instrumentation as explained in Appendix F are relevant.
The calibration requirements for selected equipment used in toy testing are detailed below.
Type of equipmentRecommended period between
successive calibrationsCalibration procedure
and requirements
FORCE AND TORQUE
MEASURING EQUIPMENT
USED FOR TOY TESTING
SUCH AS PUSH PULL GAUGE,
TORQUE GAUGE AND
TENSION GAUGE
(a) Portable spring type with dialgauge
(b) Non-portable spring type withdial gauge
One year (complete)*Six months*
(repeatability of zero)
Two years* (complete)Six months*
(repeatability of zero)
Dial gauge mechanism should bechecked for repeatability of zero with
fast and slow movement in tensionand compression, or clockwise andanticlockwise directions whereappropriate
FIXTURESincluding accessibility probes, smallparts cylinder, bite test clamp, rattletest fixture, flexure tester,compression test disc, tyre removal
metal hooks, metal cylinders, straightrods, pins, steps construction for
tumble tests, etc.
Initial calibration for dimensionalcompliance *
Yearly inspection for damage and
wear *
IMPACT MEDIUM FOR DROP
TEST
Initial calibration for hardness ofmedium *
Yearly inspection for damage and
wear *
PROJECTILE VELOCITY
TESTER
Two years * The distance between the starting andstopping sensor and the accuracy ofthe timer should be calibrated. Thesoftware for calculating the velocityfrom the distance and time readings
should be verified.
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Type of equipmentRecommended period between
successive calibrationsCalibration procedure
and requirements
SHARP EDGE TESTER Initial calibration*
(complete)
One month*(force calibration)Six months *(inspection of mandrel condition)
Calibration should be in accordance
with the requirements of relevant toytesting standards, such as those formandrel diameter, rotation speed,surface hardness, surface roughnessand force. Mandrel force calibrationmay be performed using a calibrated
dead weight.
SHARP POINT TESTER Initial calibration *Six months *(inspect the end cap for wear)
Calibration should be in accordancewith the requirements of relevant toytesting standards, such as those for
dimensions of gauging slot, thicknessof end cap, micrometer graduation
and force of spring.
After a piece of equipment is calibrated, a staff member of the laboratory should check
whether the characteristics of the equipment as shown by the calibration results are within the
tolerance range specified by the test standard. Use of out of tolerance equipment is not
recommended. In exceptional cases where it is impractical to repair or replace the
equipment, the out of tolerance equipment may be used only if the following conditions are
met :
(a) The laboratory has at least one set of working equipment with characteristics withinthe specified tolerance range which can be used to determine compliance for critical
cases.
(b) The laboratory has evaluated the effects of the out of tolerance equipment and
documented the conditions under which the out of tolerance equipment will not affect
test results.
(c) The out of tolerance equipment is properly labelled to alert test operators that such
equipment is out of tolerance and should only be used under the conditions
documented in (b). Under all other conditions, the equipment mentioned in (a)
should be employed.
(d) Test operators are properly trained and fully aware of the meaning of the label
mentioned in (c), the limitations of the use of the out of tolerance equipment and the
actions to take when the defect of the equipment may affect test results.
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