Standard Specifications for Laboratory Weights p y g and Precision

p
y Weights
g
Standard Specifications
for Laboratory
and 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.;
US;
◦ 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
Legal
lM
Metrology
t l
(I
(Industry
d t &L
Laboratory)
b
t
)
NIST Handbook 105-1: Specification and
T
l
ffor R
f
S
d d and
d
Tolerances
Reference
Standards
Field Standard Weights & Measures.
Legal metrology & commercial weighing
instruments.
instruments


NBS Circular 3 (1918)
NBS
S Circular
C
l 547 (1954)
( 9 )
◦ NBS Classes J, M, S, S-1, P, Q, & T
abo ato y C
Classes
asses A,, B,, & C
◦ State Laboratory
◦ Commercial weights referred to HB 44

ASTM E617 (1981) Industry Standard
◦ ASTM Classes 1-6
1 6
◦ Adopted by NBS/NIST

ASTM E617 (1997)
◦ Metric Only, Added Classes 0 & 7

ASTM E617 (2013)
 Uniformity
◦
◦
◦
◦
& 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
g
ASTM Class 00.
◦ Add an additional weight classification with
metrological properties similar to OIML E1 and
tolerances approximately one
one-half
half of Class 00.
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
classes
l
b
before/after
f
/ f
the
h redefinition
d fi i i
off the
h
kilogram.
Pharma, Forensic,
Biotechnology,
Silicon Valley,
Valley
etc.
Users
NIST
Mass & Force
Manufacturers
Group
NIST
Calibration
OWM
Laboratories







Major alignment with OIML R111 with the
exception of MPE/Classes 0-7.
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.
Prescriptive minimum comparisons (method).
Prescriptive environmental ranges.
P
i i stabilization
bili i
i
Prescriptive
times.
Prescriptive manufacturer verification and
subsequent
q
calibrations tests to p
perform.


Weight manufacturers must be able to
provide evidence that all new weights comply
with specifications in this standard (e.g.,
material density
material,
density, magnetism
magnetism, surface finish
finish,
mass values, uncertainties).
Calibration laboratories must meet all the
requirements of E617 to make a compliance
statement to an ASTM class.
BIPM/SI
Prototype Kilogram
NMI
Prototype Kilograms
Primary Mass
Laboratory
Accredited Mass
Calibration Lab
Mass Used On
Weighing Instrument
Measurand On
g
g Instrument
Weighing
Measurement Process:
A. Reference Standard
B. Measurand
C. Measurement Result
D. Measurement Traceability:
1. Unbroken Chain of Comparisons
2 Measurement Uncertainty
2.
3. Documented Procedure
4. Technical Competence
5. Realization of SI Units
6. Periodic Recalibration
7. Measurement Assurance
Commonly heard in the USA: “NIST-traceable”
traceable”
Correct: “SI
SI-traceable
NIST HB 105-1 (1990)
OIML R111
ASTM E617
Metric
M t i (SI units)
it )
Avoirdupois
Apothecary
Grains
SI Units
U it Only
O l (metric)
( t i )
Metric
M t i (SI units)
it )
Avoirdupois
Apothecary
Grains
Troy ounces
Pennyweight
Carats
(2013)

ASTM Class 000:
◦ New
ASTM class
tolerance
N
l
t l
◦ ≥ 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 E1 ≥ 10 gram
◦ Uncertainty must be less than 1/3 of MPE

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
more than the difference: MPE minus
expanded uncertainty, from the nominal
value of the weight.
Reported in SI units, typically milligrams.
000
00
0
1
1 kg
k
0.25
0 25 mg
0.5
0 5 mg
1.3
1 3 mg
2.5
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):
◦
◦
◦
◦
◦
◦
Avoirdupois (pounds, ounces, & fractions)
y ounces
Troy
Pennyweights
Grains
C
t
Carats
Apothecary (Ounces, Drams, Scruples)
X X



X
X x
500 µg, 300 µg, 200 µg, 100 µg, & 50 µg
S
Specifications
ifi ti
MPE for portions of ASTM Classes 000 - 6

Manufacturer Specifications:
◦
◦
◦
◦
◦
◦
◦
◦
◦
Construction
C
i
Design
Surface Area
Magnetism*
Density
Finish
Finish*
Adjustment*
Marking
Cases
*Considerations in the subsequent recalibrations of
the weight.
weight

Laboratories issuing calibration reports for
weights and weight sets shall have evidence
of metrological traceability to the
International System of Units (SI).
(SI) Calibration
certificates shall be issued only by
laboratories having
g a quality
q
y system
y
complying with the requirements of ISO/IEC
17025, which has preferably been verified by
thi
d party
t assessmentt ((accreditation).
dit ti )
third





Conventional mass of each weight
Indication if adjusted
Expanded uncertainty
Value of the coverage factor, k
Meet the requirements of ISO/IEC 17025,
Section 5.10
5 10
These represent the minimum requirements for a Certificate of
Calibration for an ASTM E617 class weight.
Weight Class
Alcohol
Al h l
Distilled H2O
000, 00, & 0
1
2
3-7
7-10
7 10 days
d
3-6
3 6 days
d
1-2
1 2 days
d
1 hour
h
4-6 days
2-3 days
1 day
1 hour
Weight Class
Range
± Per Hour
± Per 12 Hours
000,
000 00,
00 & 0
17 to
t 23.5
23 5 ºC
0.3
0 3 ºC
0.5
0 5 ºC
1
17 to 23.5 ºC
0.7 ºC
1 ºC
2
1.5 ºC
2 ºC
3
2 ºC
3.5 ºC
4-7
3 ºC
5 ºC
ASTM E617 (2013) T
Table
bl 11
If the air density deviates from 1.2 kg/m3 by more
than 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
dissemination)
Class
000, 00, 0
1
2&3
4&5
6&7
ABBA
3
2
1
1
1
ABA
5
3
2
1
1
AB….BA
5
3
2
1
1
ASTM E617 (2013) Table 12
•ABBA & ABA appropriate for weight classes 000,
000 00,
00 0
0, 1
1, 2
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 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
controll charts)
h
)
NIST Mass Code software being updated to
meet ASTM E617 & OIML R111 uncertainty
requirements and to better apply air buoyancy
corrections to measurement results


Standard uncertainty of the weighing process
Uncertainty
off the
standard
U
i
h reference
f
d d
◦ Covariance considerations must be applied
◦ Drift & instability

Uncertainty of the air buoyancy correction (ABC)
◦ ABC equation and/or estimations
y of the Reference Standard & Unknown
◦ Density
(measured or assumed)
◦ Environmental measuring equipment

Uncertainty
comparator
y of the balance/mass
/
p
◦ Sensitivity
◦ Display Resolution (zero & load)
y
◦ Eccentricity
HB 105-1 (DRAFT)
OIML R111
ASTM E617
Mandatory
&
M d t
prescriptive for
components &
calculations,, including
g
air density (based on
OIML R111
recommendations)
Mandatory
&
M d t
prescriptive for
components &
calculations,, including
g
air density.
Mandatory
&
M d t
prescriptive for
components &
calculations,, including
g
air density (based on
OIML R111
recommendations)
(2013)
Required: U ≤ 1/3 MPE Required: U ≤ 1/3 MPE Required: U ≤ 1/3 MPE
Conventional mass
and ABC on all
lib ti
calibrations
exceptt M
class.
Conventional mass
ABC Air
ABC:
Ai Buoyancy
B
C
Correction
i
Conventional mass
and ABC




Dr. George Rodrigues (Artel), ASTM E41
Committee Chair
Tracey Hill (Troemner), ASTM E617 Secretary
NIST (M
(Mass & F
Force G
Group, Offi
Office off Weights
W i h
& Measures, Adminstration)
Dr Richard Davis,
Dr.
Davis BIPM

Errata update to E617 (2013)
ASTM E898
ASTM E1154

NIST Seminars & Tutorials
◦ F
Fundamentals
d
t l off M
Metrology
t l
S
Seminars
i
(1 week)
k)
◦ Mass Seminars (2 weeks)
weeks))
◦ Advanced Mass Seminars (1-2
(
Mark Ruefenacht
Heusser Neweigh
925 798 8900
925-798-8900
mark@neweigh.com