October 2014 

GMP 8 Page 1 of 4 

GMP 8 

Good Measurement Practice 

for 

Reporting Tape Calibrations 

Tape calibration results should be reported as described in SOP 1, Preparation of 

Calibration Certificates. The use of the Calibration Certificate and Test Report Review Checklist, 

(SOP 1, Appendix B), is highly recommended. 

Information pertinent to this type of calibration should include: 

1. A note that reported lengths may be converted to catenary suspension support 

lengths by use of the “Equations for Metallic Tapes” (GMP 9); 

2. Description of the procedure, and the position of the test artifact relative to the 

observer; 

3. Tension applied to the tape during the test; 

4. Type of support, e.g., continuous, catenary (include information regarding 

spacing); 

5. The assumed linear coefficient of expansion for the tape material; 

6. The relationship between the International System of Units (SI) and US 

customary units; 

7. The degrees of freedom (effective) associated with the coverage factor k;

8. AE value, if requested by customer; and 

9. Weight per Unit Length, if requested by customer. 

An example of a Calibration Certificate follows in the Appendix. 
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GMP 8 Page 2 of 4 

Appendix – Example 

COMPLIANT CALIBRATION LABORATORY 

123 Some Ave. 

City, State 12312-1231 

CALIBRATION CERTIFICATE 

FOR 

25 foot Iron-Nickel Alloy Tape 

Maker: LUFSTARTOYO Lab Test No.: TI-14-056

Serial No.: C917R NMI Test No.: 822/1234 

SUBMITTED BY 

YOUR CUSTOMER, INC. 

Customer’s Address 

City, State 

This tape has been compared to the standards of Compliant Calibration Laboratory. The 

horizontal distances between the centers of graduations of the indicated intervals have the 

following lengths at 20 °C (68 °F) when the tape is subjected to 10 pound horizontally applied 

tension and supported on a horizontal flat surface. The terminal points of the indicated intervals 

are the centers of the graduations at the edge of the tape ribbon nearest the observer when the 

zero graduation is to the left. 

Interval 

(feet) 

Length 

(inches) 

Uncertainty 

(inches) 

Interval 

(feet) 

Length 

(inches) 

Uncertainty 

(inches) 

0 to 1 12.000 3 0.001 0 0 to 14 167.999 4 0.001 0 

0 to 2 24.000 5 0.001 0 0 to 15 180.000 1 0.001 0 

0 to 3 36.000 3 0.001 0 0 to 16 192.000 4 0.001 0 

0 to 4 48.000 2 0.001 0 0 to 17 204.000 3 0.001 0 

0 to 5 59.999 8 0.001 0 0 to 18 216.000 2 0.001 0 

0 to 6 71.999 6 0.001 0 0 to 19 220.000 4 0.001 0 

0 to 7 84.000 2 0.001 0 0 to 20 239.999 8 0.001 0 

0 to 8 96.000 1 0.001 0 0 to 21 252.000 4 0.001 0 

0 to 9 108.000 2 0.001 0 0 to 22 264.000 1 0.001 0 

0 to 10 120.000 4 0.001 0 0 to 23 275.999 7 0.001 0 

0 to 11 132.000 4 0.001 0 0 to 24 287.999 6 0.001 0 

0 to 12 144.000 2 0.001 0 0 to 25 300.000 7 0.001 0 

0 to 13 155.999 6 0.001 0 

The data in the above table only applies to those items specifically listed on this report. 

This document does not represent or imply endorsement by Compliant Calibration Laboratory, NMI, or any agency of the State and/or national 

governments. This document may not be reproduced, except in full, without the written permission of Compliant Calibration Laboratory. 

Page 1 of 3 
October 2014 

GMP 8 Page 3 of 4 

Reported lengths may be converted to catenary suspension support lengths by use of the 

“Equations for Metallic Tapes” (GMP 9).

The exact relationship between the International System of Units (SI) and the US customary 

units of length is one foot equals 0.304 8 meter. 

Uncertainty statement: 

The combined standard uncertainty includes the standard uncertainty reported for the standard, 

the standard uncertainty for the measurement process, the standard uncertainty of the coefficient 

of expansion, the standard uncertainty of the tension weights, the standard uncertainty of the 

graduated reticle, and a component of uncertainty to account for any observed deviations from 

NIST values that are less than surveillance limits. The combined standard uncertainty is 

multiplied by a coverage factor of 2.07, for 35 effective degrees of freedom, to provide an 

expanded uncertainty, which defines an interval having a level of confidence of approximately 

95 percent. The expanded uncertainty presented in this report is consistent with the ISO/IEC 

Guide to the Expression of Uncertainty in Measurement (2008). The expanded uncertainty is not 

to be confused with a tolerance limit for the user during application. 

Traceability statement: 

The Standards of the Compliant Calibration Laboratory are traceable to the International System 

of Units (SI) through the National Institute of Standards and Technology, and are part of a 

comprehensive measurement assurance program for ensuring continued accuracy and 

measurement traceability within the level of uncertainty reported by this laboratory. The 

laboratory test number identified above is the unique report number to be used in referencing 

measurement traceability for artifacts identified in this report only. 

Supplemental Information 

Description of artifacts submitted for testing: 

25 foot, iron-nickel alloy (invar), tape. A linear coefficient of thermal expansion of 

0.000 000 4 /°C (0.000 000 22 /°F) was assumed. 

Conditions of artifacts submitted for testing: 

Artifact showed evidence of proper handling. No bents or kinks were observed. A light film of 

oil covered the tape ribbon. 

Treatment of artifacts prior to testing: 

Artifact was cleaned with cheesecloth and alcohol to remove the protective oil film. The artifact 

was kept in the length laboratory, next to the standard, for 36 h to allow for thermal equilibrium. 

Equipment & Standards 

Standard: Length bench Calibrated: August 2014 

Tension weights: 10 pound, Class F

Microscope: B&L, 0.002 inch graduated reticle 

This document does not represent or imply endorsement by Compliant Calibration Laboratory, NMI, or any agency of the State and/or national 

governments. This document may not be reproduced, except in full, without the written permission of Compliant Calibration Laboratory.

Page 2 of 3 
October 2014 

GMP 8 Page 4 of 4 

Procedure used: NISTIRXXXX, SOP 11, Calibration of Metal Tapes, Bench Method 

Environmental conditions at time of test: 

Temperature: 20.1 C to 20.2 C Barometric Pressure: 752.7 mm Hg 

Relative Humidity: 43.35 % to 43.40 % 

Date artifact was received: September 15, 2014 

Date of test: September 17, 2014 

Due date per customer’s request: September 17, 2016 

Date of report preparation: September 18, 2014 

 Josh Balani, Jr. 

Test performed by: Josh Balani, Jr. 

 Metrology Expert 

Member: 

NCSLI 

NCWM 

ASQ 

ASTM 

This document does not represent or imply endorsement by Compliant Calibration Laboratory, NMI, or any agency of the State and/or national 

governments. This document may not be reproduced, except in full, without the written permission of Compliant Calibration Laboratory.

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