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Standard Specifications for Laboratory Weights p y gand Precision Mass Standards (2013 Revision)
NCSLI 2013 Nashville
At the end of this technical session, you will be able to:◦ Name the three major weight specifications used in
the U S ;the U.S.;◦ Identify the new ASTM weight classifications;◦ Visualize the new microgram weights;◦ Summarize the significant changes in ASTM E617;
ASTM E617: Standard Specification for Laboratory Weights and Precision Mass Standards. Industry & Laboratory Standard.
OIML R111: Metrological & Technical Requirements for Classes E1 to M3 used for verification of weighing instruments and calibration of weights of a lower accuracy class.L l M t l (I d t & L b t )Legal Metrology (Industry & Laboratory)
NIST Handbook 105-1: Specification and T l f R f S d d dTolerances for Reference Standards and Field Standard Weights & Measures. Legal metrology & commercial weighing instrumentsinstruments.
NBS Circular 3 (1918)S C l ( 9 ) NBS Circular 547 (1954)
◦ NBS Classes J, M, S, S-1, P, Q, & T◦ State Laboratory Classes A, B, & CState abo ato y C asses , , & C◦ Commercial weights referred to HB 44
ASTM E617 (1981) Industry StandardASTM Classes 1 6◦ ASTM Classes 1-6◦ Adopted by NBS/NIST
ASTM E617 (1997)◦ Metric Only, Added Classes 0 & 7
ASTM E617 (2013)
Uniformity & ConsistencyUniformity & Consistency◦ Users of ASTM classified mass standards◦ Mass calibration laboratories◦ ISO/IEC 17025:2005 Assessors◦ Accrediting Bodies
Weight Tolerance Classes:◦ Add an additional weight classification with
metrological properties and tolerances similar to OIML E1. Designated ASTM Class 00.g◦ Add an additional weight classification with
metrological properties similar to OIML E1 and tolerances approximately one half of Class 00tolerances approximately one-half of Class 00. Designated ASTM Class 000.
Add sub-milligram weights of nominal values 500, 300, 200, 100 & 50 micrograms (µg).
Support the new ASTM E617 weight classes. Redefinition of the kilogram. Uncertainties to support the new weight
l b f / f h d fi i i f hclasses before/after the redefinition of the kilogram.
Users
Pharma, Forensic, Biotechnology, Silicon ValleyUsers Silicon Valley,
etc.
Manufacturers
NIST
Mass & Force
Group
Calibration
Laboratories
NIST
OWM
Major alignment with OIML R111 with the exception of MPE/Classes 0 7 Move towardsexception of MPE/Classes 0-7. Move towards international harmonization while meeting the needs of U.S. industry/commerce.
Sub-milligram weight specifications. Mandatory and prescriptive uncertainty
components & estimation.components & estimation. Prescriptive minimum comparisons (method). Prescriptive environmental ranges.
P i i bili i i Prescriptive stabilization times. Prescriptive manufacturer verification and
subsequent calibrations tests to perform.q p
Weight manufacturers must be able to provide evidence that all new weights comply with specifications in this standard (e.g., material density magnetism surface finishmaterial, density, magnetism, surface finish, mass values, uncertainties).
Calibration laboratories must meet all the Calibration laboratories must meet all the requirements of E617 to make a compliance statement to an ASTM class.
BIPM/SIPrototype KilogramPrototype Kilogram
NMIPrototype Kilograms Measurement Process:
Primary Mass Laboratory
A. Reference StandardB. MeasurandC. Measurement ResultD. Measurement Traceability:
1. Unbroken Chain of Comparisons2 Measurement Uncertainty
Accredited Mass Calibration Lab
Mass Used On
2. Measurement Uncertainty3. Documented Procedure4. Technical Competence5. Realization of SI Units6. Periodic Recalibration7. Measurement Assurance
Mass Used OnWeighing Instrument
Measurand OnWeighing Instrument
Commonly heard in the USA: “NIST-traceable” Correct: “SI traceable”g g Correct: SI-traceable
NIST HB 105-1 (1990) OIML R111 ASTM E617 (2013)
M t i (SI it ) SI U it O l ( t i ) M t i (SI it )Metric (SI units)AvoirdupoisApothecaryGrains
SI Units Only (metric) Metric (SI units)AvoirdupoisApothecaryGrainsTroy ouncesPennyweightCarats
ASTM Class 000:N ASTM l t l◦ New ASTM class tolerance
◦ ≥ 1 gram is approximately one-half of ASTM Class 00◦ Uncertainty must be less than 1/3 of MPE
ASTM Class 00:◦ New ASTM class tolerance
Alignment to OIML Class E ≥ 10 gram◦ Alignment to OIML Class E1 ≥ 10 gram◦ Uncertainty must be less than 1/3 of MPE
ASTM Class 0 – 7: ASTM Class 0 7:◦ No changes to maximum permissible errors◦ Uncertainty must be less than 1/3 of MPE
The expanded uncertainty of the conventional mass shall be less than or equal to one-third of the MPE.
The conventional mass shall not differ by The conventional mass shall not differ by more than the difference: MPE minus expanded uncertainty, from the nominalexpanded uncertainty, from the nominal value of the weight.
Reported in SI units, typically milligrams.
000 00 0 11 k 0 25 0 5 1 3 2 51 kg 0.25 mg 0.5 mg 1.3 mg 2.5 mg
50 µg 0.002 mg 0.003 mg 0.005 mg ---
SI/Metric (kilogram, gram, & milligram) Reestablished MPE for the following
measurement units (restored from E617 revision 1981):revision 1981):◦ Avoirdupois (pounds, ounces, & fractions)◦ Troy ouncesy◦ Pennyweights◦ Grains
C t◦ Carats◦ Apothecary (Ounces, Drams, Scruples)
X X X X xX X X X x
500 µg, 300 µg, 200 µg, 100 µg, & 50 µg S ifi ti Specifications
MPE for portions of ASTM Classes 000 - 6
Manufacturer Specifications:C i◦ Construction◦ Design◦ Surface Area◦ Magnetism*◦ Density◦ Finish*Finish◦ Adjustment*◦ Marking◦ Cases◦ Cases
*Considerations in the subsequent recalibrations of the weightthe weight.
Laboratories issuing calibration reports for weights and weight sets shall have evidence of metrological traceability to the International System of Units (SI) CalibrationInternational System of Units (SI). Calibration certificates shall be issued only by laboratories having a quality system g q y ycomplying with the requirements of ISO/IEC 17025, which has preferably been verified by thi d t t ( dit ti )third party assessment (accreditation).
Conventional mass of each weight Indication if adjusted Expanded uncertainty Value of the coverage factor, k Meet the requirements of ISO/IEC 17025,
Section 5 10Section 5.10
These represent the minimum requirements for a Certificate of Calibration for an ASTM E617 class weight.
Weight Class 000, 00, & 0 1 2 3-7Al h l 7 10 d 3 6 d 1 2 d 1 hAlcohol 7-10 days 3-6 days 1-2 days 1 hourDistilled H2O 4-6 days 2-3 days 1 day 1 hour
Weight Class Range ± Per Hour ± Per 12 Hours000 00 & 0 17 t 23 5 ºC 0 3 ºC 0 5 ºC000, 00, & 0 17 to 23.5 ºC 0.3 ºC 0.5 ºC
1 17 to 23.5 ºC 0.7 ºC 1 ºC2 1.5 ºC 2 ºC3 2 ºC 3.5 ºC
4-7 3 ºC 5 ºC
ASTM E617 (2013) T bl 11ASTM E617 (2013) Table 11
If the air density deviates from 1.2 kg/m3 by more than 10 % (true) mass values shall be used inthan 10 %, (true) mass values shall be used in calculations and the conventional mass shall be calculated from the (true) mass.
Two methods for the determination of the conventional mass of weights:◦ Direct comparison◦ Subdivision/multiplication (commonly known as◦ Subdivision/multiplication (commonly known as
dissemination)
Class 000, 00, 0 1 2 & 3 4 & 5 6 & 7ABBA 3 2 1 1 1ABA 5 3 2 1 1
AB….BA 5 3 2 1 1
ASTM E617 (2013) Table 12
•ABBA & ABA appropriate for weight classes 000 00 0 1 2 & 3•ABBA & ABA appropriate for weight classes 000, 00, 0, 1, 2, & 3•AB…BA may be used for weight classes 4, 5, 6, and & 7•AB…BA may be used for weight classes 000, 00, 0, 1, 2, & 3 if a mass comparator with an automatic weight exchangea mass comparator with an automatic weight exchange mechanism is used and if the system is installed in a protecting housing.
Based on the GUM & supplements Based on repeatability of the intercomparisons Based on historical data (check standards and
l h )control charts)
NIST Mass Code software being updated to NIST Mass Code software being updated to meet ASTM E617 & OIML R111 uncertainty requirements and to better apply air buoyancyrequirements and to better apply air buoyancy corrections to measurement results
Standard uncertainty of the weighing processU i f h f d d Uncertainty of the reference standard◦ Covariance considerations must be applied◦ Drift & instability
Uncertainty of the air buoyancy correction (ABC)◦ ABC equation and/or estimations◦ Density of the Reference Standard & Unknown y
(measured or assumed)◦ Environmental measuring equipment
Uncertainty of the balance/mass comparatory / p◦ Sensitivity◦ Display Resolution (zero & load)◦ Eccentricityy
HB 105-1 (DRAFT) OIML R111 ASTM E617 (2013)
M d t & M d t & M d t &Mandatory & prescriptive for components & calculations, including
Mandatory & prescriptive for components & calculations, including
Mandatory & prescriptive for components & calculations, including , g
air density (based on OIML R111recommendations)
, gair density.
, gair density (based on OIML R111recommendations)
Required: U ≤ 1/3 MPE Required: U ≤ 1/3 MPE Required: U ≤ 1/3 MPEConventional mass and ABC on all
lib ti t M
Conventional mass Conventional mass and ABC
calibrations except M class.
ABC Ai B C iABC: Air Buoyancy Correction
Dr. George Rodrigues (Artel), ASTM E41 Committee Chair
Tracey Hill (Troemner), ASTM E617 SecretaryNIST (M & F G Offi f W i h NIST (Mass & Force Group, Office of Weights & Measures, Adminstration)
Dr Richard Davis BIPM Dr. Richard Davis, BIPM
Errata update to E617 (2013)
ASTM E898ASTM E898 ASTM E1154
NIST Seminars & TutorialsF d t l f M t l S i (1 k)◦ Fundamentals of Metrology Seminars (1 week)◦ Mass Seminars (2 weeks)◦ Advanced Mass Seminars (1-2 weeks)( )
