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GMP 12

Good Measurement Practice 

for

Standard Operating Procedure Selection

Good laboratory practices, use of proper standards and equipment, and selection of standard operating 

procedures are essential for providing calibration results with accurate and traceable values with 

appropriate and suitable uncertainties. The following matrix recommends SOPs based on the 

parameter, type of calibration items, and level of uncertainty needed.

Table 1. Procedure Selection Table.

 1 See Table 2 for complete Titles for the Documentary Standard references used in Table 1.

Parameter or 

Documentary 

Standard1

Calibration Item Recommended SOP

Mass (NISTIR 6969 and NISTIR 5672)

Railroad test cars SOP 27, Railroad Test Cars using a Master Track 

Scale

HB 105-8 Weight carts SOP 33, Calibration of Weight Carts (References 

SOP 4 and SOP 7)

HB 105-1, Class F

ASTM, OIML

Class F

Class 5, 6, 7

Class M1, M2, M3

e.g., 10 kg to 

250 kg (≥ 500 lb) cast iron

1 mg to 5 kg

(1 μlb to 10 lb) stainless 

steel

SOP 8, Modified Substitution - may be used if 

expanded uncertainty is less than 1/3 of the 

tolerance 

SOP 7, Single Substitution - to be used, as a 

minimum, if conditions given for SOP 8 cannot be 

met

NOTE: Balances and standards must be selected 

properly for these conditions to be met.

ASTM, OIML

Class 3, 4 (P)

Class F1, F2

e.g., 1 kg kit, 100 g kit

SOP 7, Single Substitution - may be used if 

expanded uncertainty is less than 1/3 of the 

tolerance. If uncertainty is greater than 1/3 of the 

tolerance, then use SOP 4.

SOP 4, Double Substitution - to be used for 

buoyancy corrections and if expanded uncertainty 

is less than 1/3 of the tolerance

NOTE: Balances and standards must be selected 

properly for these conditions to be met.

ASTM, OIML

Class 1, 2 (S, S-1)

Class E2

When used for balance 

calibration

SOP 5, 3-1 Weighing Design (preferred)

SOP 4, Double Substitution - to be used for 

buoyancy corrections and if expanded uncertainty 

is less than 1/3 of the tolerance

ASTM, OIML

Class 000, 00, 0, 1 (S)

Class E1

When used as laboratory 

standards

Weighing Designs per NIST Technical Note (TN) 

952, TN 844, NISTIR 5672, SOP 28, with 

appropriate check standards;

SOP 5, 3-1 Weighing Design (optional)
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Volume (NISTIR 7383)

HB 105-2 Glass flasks

SOP 14, Gravimetric Calibration of Volumetric 

Standards Using an Electronic Balance

SOP 16, Calibration of Measuring Flasks

Volume Transfer Method (acceptable)

HB 105-3 20 L test measures

(5 gal or 10 gal)

Preferred: SOP 19, Calibration of Graduated 

Neck-Type Metal Provers (Volume Transfer 

Method) is preferred. When temperature 

instability is observed during the calibration 

process, SOP 19 must be used. 

SOP 31, Scale Plate Calibration for Volumetric 

Field Standards

SOP 18, Calibration of Graduated Neck-Type 

Metal Volumetric Field Standards Using a 

Slicker-Plate Type Standard, may be used if 

temperature stability and limits are acceptable 

(single delivery from slicker plate type standard; 

for glass standards use SOP 19. 

HB 105-3

Large graduated neck type 

provers - used for meter 

verification

SOP 19, Calibration of Graduated Neck-Type 

Metal Provers (Volume Transfer Method)

SOP 31, Scale Plate Calibration for Volumetric 

Field Standards

HB 105-4 LPG provers

SOP 21, Calibration of LPG Provers

SOP 31, Scale Plate Calibration for Volumetric 

Field Standards

HB 105-7

Compact Displacement 

Prover (Small Volume 

Provers)

SOP 26, Gravimetric Calibration of Dynamic 

Volumetric Systems used as Standards

Laboratory standards

Glassware: burets, 

pipettes, flasks

SOP 14, Gravimetric Calibration of Volumetric 

Standards Using an Electronic Balance

Laboratory standards

Laboratory slicker plate 

standards

SOP 14, Gravimetric Calibration of Volumetric 

Standards Using an Electronic Balance

Micropipettes SOP 14, Gravimetric Calibration of Volumetric 

Standards Using an Electronic Balance

HB 105-3

Large graduated neck type 

provers - used as 

laboratory standards

SOP 19, Calibration of Graduated Neck-Type 

Metal Provers (Volume Transfer Method) OR

SOP 14, Gravimetric Calibration of Volumetric 

Standards Using an Electronic Balance

SOP 31, Scale Plate Calibration for Volumetric 

Field Standards
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Length (NISTIR 8028)

Tapes SOP 11, Bench Method (lower uncertainties) OR

SOP 12, Tape to Tape 

Rigid Rules SOP 10, Rigid Rule 

Pi Tapes SOP 23, Pi Tape Calibration

Liquid-in-Glass Thermometers

HB 105-6 Field standards for 

weights and measures SOP 25 (unpublished)

Timing Devices

HB 105-5 Field standards for 

weights and measures

SOP 24 (unpublished)

Traffic Speed Gun Tuning Forks

For enforcement official 

use

SOP 22 (unpublished)

Measurement Assurance

All Process 

Measurement Assurance SOP 30 Use of process measurement assurance programs

Mass SOP 5, 28 Use of check standards in procedure

TN 952, TN 844, NISTIR 5672

Mass SOP 4, 6, 7, 8 SOP 9

Length SOP 10, 11, 12, 23 Redundancy built into procedures with replicate 

measurements

Volume SOP 13, 14, 15, 16, 18, 

19, 21, 26

SOP 17, laboratory check standards OR

SOP 20, standard deviation charts and range 

charts

Temperature SOP 25 Use of check standards in procedure (SOP 30, 

SOP 17)

Uncertainty

All parameters All SOPs

SOP 29, Calculation of Uncertainty

Note: Each SOP for calibration procedures 

includes a detailed uncertainty budget table 

template identifying common components to be 

included.
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Table 2. Documentary Standard References.

Documentary 

Standard Number Title Latest Revision Date

105-1 Specifications and Tolerances for Field Standard Weights 

(NIST Class F)

2019

105-2 Specifications and Tolerances for Field Standard Measuring 

Flasks

1996

105-3 Specifications and Tolerances for Graduated Neck Type 

Volumetric Field Standards

2010

105-4 Specifications and Tolerances for Liquefied Petroleum Gas and 

Anhydrous Ammonia Liquid Volumetric Provers

2016

105-5 Specifications and Tolerances for Field Standard Stopwatches 1997

105-6 Specifications and Tolerances for Thermometers 1997

105-7 Specifications and Tolerances for Dynamic Small Volume 

Provers

1997

105-8 Specifications and Tolerances for Field Standard Weight Carts 2019

ASTM E617 Standard Specification for Laboratory Weights and Precision 

Mass Standards

2018

OIML R111 Weights of classes E1, E2, F1, F2, M1, M1–2, M2, M2–3 and M3

Part 1: Metrological and technical requirements

2004