N8SIR 74-462

Interlaboratory Comparisons of

Static Force Calibrations

R. W. Peterson

Engineering Mechanics Section

Mechanics Division

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

June 1974

Summary Report

Covering Period 7/15/71 to 12/31/73

Prepared for

Department of Defense

Calibration Coordination Group

Working Group on Mass and Pressure

Project No, 72=61
i
NBSIR 74-462

INTERLABORATORY COMPARISONS OF

STATIC FORCE CALIBRATIONS

R. W. Peterson

Engineering Mechanics Section

Mechanics Division

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

June 1974

Summary Report

Covering Period 7/15/71 to 12/31/73

Prepared for Department of Defense

Calibration Coordination Group

Working Group on Mass and Pressure

Project No. 72-61

U. S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts. Director

Interlaboratory Comparisons of

Static Force Calibrations

1. SCOPE

This report covers phase I of a program of interlaboratory comparisons of static force calibrations developed for the Calibration Coordination group of the Department of Defense. The objective of the program is to allow each participating laboratory to examine the quality of

its force calibration capabilities. Phase I includes force measurements

up to 20,000 lbf.

Four force measuring devices were circulated to each of the five

participating laboratories. Each was asked to perform calibrations in

both tension and compression at, as nearly as possible, ten specified

loads over the range of each device. Procedures normally employed by

each laboratory were to be used. The devices were divided into two

groups, each routed through the laboratories in a different order. All

devices were calibrated at the National Bureau of Standards before distribution and again at the termination of the routing. The two groups of

devices consisted of the following:

Group A One 2,000-lbf capacity proving ring

One 20,000-lbf capacity proving ring

Group B One 2,000-lbf capacity load cell

One 20,000-lbf capacity load cell

One electronic readout

Both groups of devices were to be calibrated over the same ranges.

All laboratories used the same span setting for the load cell system.

The original data for all calibrations were transmitted to the

National Bureau of Standards. All data for the proving ring calibrations were corrected to 23 °C. No corrections were applied to the load cell

data. Second degree equations, with the load as the independent variable, were fitted to the average load readings from each laboratory using the

method of least squares. The initial NBS calibration curves were selected

as the base for comparison with the curves fitted to the individual

laboratory data. To permit comparisons between devices, all curves were

normalized using the initial NBS value at the maximum load (2,000 lbf or 20,000 lbf) as an arbitrary reference. Points on the individual curves corresponding to the nominal calibration loads are expressed as a percentage of the reference base.

2. TEST PROCEDURE

3. DATA REDUCTION
4. SUMMARY OF RESULTS

The values from the curves fitted to the primary data, the corresponding normalized values, and the normalized differences from the firstNBS calibration are given in Tables 1 through 8. Standard deviations and

curve coefficients for each calibration curve are presented in Table 9«

Figures 1 through 6 show comparisons of normalized calibration curves against the initial NBS calibration curves. Two laboratories, A and D,

did not calibrate any of the devices in tension.

With the exception of Laboratory C's tension calibration of the

2,000-lbf proving ring, all calibrations agreed to within 0.1 percent of

capacity of the reference series of calibrations. There is evidence in

Figure 6 that the 2,000-lbf proving ring showed a marked increase in

short-term non-linearity during the series of calibrations. This is also

suggested by the change in standard deviation in compression shown in

Table Q. The small load cell appears to have a uniform change in output

increasing to about 0.05 percent at capacity, with respect to the FirstNBS calibration. The two 20,000-lbf devices show only insignificant

changes

5. CONCLUSIONS

In general, the intercomparison of data for the 2,000-lbf to

20,000-lbf range agreed to within acceptable limits. The intercomparison

of data for the 200-lbf to 2,000-lbf range was inconclusive due to the

apparent instability of the test devices being calibrated. Although no serious problem areas were apparent from the data furnished by the various

laboratories, there was no basis for evaluation of tension calibration

capabilities of the two laboratories that did not supply tension calibration data.

Comparison of the results was complicated by factors such as nonuniformity of test procedures, variations in methods of reporting results,

and apparent instability of at least one of the test devices. Information

about these factors was obtained that will be useful in planning further

tests, but a more comprehensive analysis of the current data did not seem

to be justified.

6. RECOMMENDATIONS FOR FUTURE TESTS

If this program is continued, consideration should be given to the

following

1. Greater or smaller load ranges

2. More stable test devices

3. Frequent checks by NBS of instrument stability during

laboratory circuit
4. Use of a uniform calibration procedure

5. Full and/or expanded participation of interested

laboratories.

3

OMN I TAB ~ COMPARISON WITH FIRST-MBS CALIBRATION

TABLE 1 - CALIBRATION DATA FOR 23 DEGREES C

2»000 L*F MOREHOUSE PROVING RING NO. 144

COMPRESSION

i A a rs LO AU r 1Kb 1 LAB LAB 1 A D 1 A D LAB 1 A Q L A b r I N AL

LBF NB5 A B c D E NBS

SECOND-DEGRE r n iR\/r U fll 1 ire

?0Cm 1 ' 0\J .• 58.10 58.22 58.09 58.11 mJ • X i Sfl . 23 58 . 2 A 5ft . 43

400 . 116.5* 116.69 116.57 116.64 116.74 116.77 116.88

600 . 175. 45 175.55 1 75.46 175.57 175.65 175.

7 175.73

800. 234.74 234.81 234.74 234.90 234.97 234.96 234.98

lono

294 . 43 294.48 294.42 294.63 294.70 294 .65 294 . b4

1 o n

1 ? 1' O • 354.54 354.49 354.77 354.84 -XCI± 7/i f> ti 71 O" M- • 1 1 1400 . 415.03 415.01 414.97 415.31 415.38 41b . 22 415.18

1 c r\ r» 1600 .

f i 7 C nC 475.87 475.84 476.24 476.33 4 f b • 09 4 f b • ub

i q n n 537,2b 537. 13 537.11 537.58 537.69 53 / .37 53 r . 34

^ o a n 2000

598 . ^7 598.80 598.78 599.32 599.46 599 ,03 59H ,02

NORMALISED CURVE VALUES

rinnUU • V . / U 'J 9.720 9.698 9.701 9.722 7 • ' db o 7 ^ c; 400. 19.462 19.480 19.461 19.472 19.490 19.494 19.512

600. 29.292 29.308 29.293 29.311 29.325 29.327 2^.337

800. 39.189 39.202 39. 189 39.216 39.228 39.226 39.230

i n n n 1 U U U * 49. 155 49. 162 49. 153 49. 189 49.200 49. 191 49.190

l ?o o

59.188 59.l9n 59. 181 59.228 59.239 59.223 59.218

X *T u u • 69.289 69.284 69.278 69.334 69.347 69.320 69.313

loUU • 79.458 79.445 79.441 79.508 79.523 79.483 79.477

i onn

89.695 89.673 0.9.669 89.7£+8 89.766 89.712 89.707

tUUU jnnn .i 100.000 99.968 99.965 100.056 100.078 100.007 100.005

NORMALISED DIFFERENCES FROM FIRST-NBS CALIBRATION

200. .000 .019 -.002 .000 .022 .026 .055

400. .000 .018 -.001 .010 .027 .032 .050

6H0. .000 .016 .001 .019 . 033 .035 .046

800 . .000 .012 .000 .027 .039 .037 .041

1000. .000 .008 -.002 .034 .045 .037 .036

1200. .000 .002 -.007 .040 .051 ' .03^ .030

1400. .000 -.005 -.011 .045 .058 .031 .024

1600. .000 -.013 -.018 .050 .064 .025 .018

1800. .000 -.022 -.026 .053 .071 .017 .012

2000. .000 -.032 -.035 .056 .078 .007 .005
OMNI TAB - COMPARISON WITH FIRST-NBS CALIBRATION

TABLE 2 - CALIBRATION DATA ^OR 23 DEGREES C

2>QO0 LPF MOREHOUSE PROVING RING NO. 144

TENSION

LVnU FIRST LAB LAR LAB LAB LAB FTNAI

Lnr MqC c n F

SECOMD-DEGRE r CURVE VALUES

2D0

57.64 5 7 .67 57.70 57.34 57. 50

400. 114.96 1 14.97 115.07 114.68 114.83

600171 ,92 171,91 1 "7 o no 1 1 1 . b7 171.81

800. 228.53 228.49 £<CO • (J 228.44

1000

284 • 78 284 .71 one n ~t 20H • oO 284 .71

i 1 a a 1200 •

"2 / 1 A f "7 340*6' 340 * 57 nil ill n c/i JHU .DM. 1400 • in/ a 1 396 t 21 396 . 06

1600 • "51 • 39 a 5 1 .20 fit; i q"t /. C 1 It St 451 • ^M-

•8 O A A 1800 • r n £ A a 506 . 22 50 5 » 9

IT A £. 1 i 506.31

a r> ft ooO

560 • 39 Sa 1 a"^ rad JOU • Ano u 560 • oo

IN ( ) K ivl A l_ I ^- C. U CURVE VAI UFS

'

) U •

1 n o q 1 1 U . ttn J- 1 U . too 10.292 10.226

400. 20.504 20.505 20.523 20.453 20.480

600. 30.663 30.661 30.692 30.618 30.642

800. 40.759 40.752 40.799 40.720 40.742

i nnn

50 . 791 50.779 50.843 50.760 50.779

120060 . 760 60.742 60.826 60.737 60.754

140070 .665 70.638 70.746 70.652 70.666

X U v • 80.507 80.473 80.603 80.503 80.515

IflOO • 90 • 285 Q0.241 90.399 90.293 90.301

p n n n

X U U . U <-* V Q9.947 100.132 100.019 100.025

MORMAI T 7FD DIFFERENCES FROM FIRST-NBS CALIBRATION

200. .000 .005 .011 -.055 -.026

400. .000 .001 .019 -.051 -.024

600. .000 -.003 .029 -.045 -.021

800. .000 -.007 .040 -.039 -.017

1000. .000 -.012 .052 -.031 -.012

1200. .000 -.018 .066 -.023 -.006

1400. .000 -.027 .080 -.014 .001

1600. .000 -.034 .096 -.004 .008

1800. .000 -.044 .113 .007 .016

2000. .000 -.053 .132 .019 .025
OMNITAB - COMPARISON WITH FIRST-NBS CALTBRATIOM

TABLE 3 - CALIBRATION DATA FOR 23 DEGREES C

2»000 LRF BLH LOAD CELL NO. 51841

COMPRESSION

LOAD FIRST LAB LAB LAB LAB 1 an LAB FINAL

LRF NBS A B C D E NBS

SECOND-DEGREE r i ir\/c- \/ A | 1 ire

200

4727. 4733. 4726. 4731

4716. 4 7 28

4730

uoo. 9457. 9460. 9454. 9462. 9U49. 9456. 9458.

600. 14187. 14187. 14183. 14193. 14183. 14183. 14187.

800. 18918. 18915. 18911. 18925. 18918. 18 Q 10. 18915.

1000. 23649. 23644. 23640. 23657. 23653. 23638. 23644.

1200. 28380. 28373. 28370. 28390. 28389. 28366. 28373.

iuno. 33113. 33102. 33099. 33123. 33125. 33095. 33102.

1600. 37845. 37832. 37829. 37856. 37863. 37823. 37831.

1800. 42578. 42563. 42559. 42589. 42601. 42552* 42561.

2000. 47312. 47294. U7289. 47323. 47339. 47281. 47291.

NORMALISED CURVE VALUES

200. 9.992 10.005 9.989 9.9Q9 9.Q67 9.994 9.998

400. 19.989 19.995 1 Q. Q 82 19.999 19.972 19.986 19.991

600. 29.987 29.987 29.978 30.000 29.978 29.978 29.985

800. 39.985 39.980 39. Q 71 40.001 39.985 39.970 39.980

1000 . 49.985 49.974 49.967 50.003 49.994 49.963 49.974

1200. 59.986 59.970 59.964 60.006 60.004 59.956 59.970

1400. 69.988 69.966 69.959 70.009 70.015 69.950 69.966

1600. 79.991 79.964 79.957 80.013 80.028 79.944 79.962

1A00. 89.995 89.963 89.955 90.018 90.043 89.939 89.959

2000. 100.000 99.963 99.952 100.024 100.059 99.935 99.956

NORMALISED DIFFERENCES FROM FIRST-NBS CALIBRATION

200. .000 .013 -.003 .007 -.025 .002 .006

400,000 .007 -.006 .010 -.017 .003 .003

600. .000 .001 -.009 .013 -.009 . 009 -.001

800. .000 -.005 -.014 .016 -.000 .015 -.006

1000. .000 -.011 -.019 .018 .008 .023 -.011

1200. .000 -.017 -.022 .020 .018 .030 -.016

1400. .000 -.022 -.029 .021 .027 .038 -.022

1600. .000 -.027 -.034 .022 .037 .047 -.029

1800. .000 -.032 -.040 .023 .048 .056 -.036

2000. .000 -.037 -.048 .024 .059 .065 -.044
OMNI TAB - COMPARISON WITH FIRST-NBS CALIBRATION

TABLE 4 - CALIBRATION DATA FOR 23 DEGREES C

2r000 LBF R LH LOAD CELL NO. 51841

TENSION

1 OAD FIRST LAB LAB LAB LAB LAB FINAL

LPF MRS A B C D E

SECOND-DEGREE CURVE VALUES

200

4734. 4729. 4731. 4731. 4734.

400. 9463. 9455. 9460. 9458. 9462.

600. 14190. 14178. 1 •+ 1 O f • 14187.

800. 18916. 18900. 1 QQ1 -2

i. as X O •

1 AQH6 18910.

1000 . 23640

2362 0 • (.JOJ 1 . 236,31 .

1 o n n I c u U . <COOfc>l * CO JDU

O A"*. HQ

T "X A O 1 7 1 c "*.^n a 1 JJUDlA 1

1600 • 37 f 99

377 f 0

37 Afl 1 "*.777 ci 37 7oU

1 r> O H-2bl 3 .

/i 1 /I Q tiom TC Jj.71 q £l9U. A7

O A A O 2000 •

j i ^ o O Q <i "7 1 Q/l M-7 1 . U71 Q7

NOPMALT ZED CURVE VALUES

C.POD. v V 1

i n . n?3 A. \J 9 \J X \J 10.018 10.016 10.024

400. 20.036 20.019 20.030 20.025 20.034

600. 30.046 30.019 30.039 30. 030 30.038

800. 40.051 40.017 40.045 40.030 40.038

i noo

X U U v • SO . 053 50.011 50.047 50.025 50.034

1200 . 60 .050 60.003 60.047 60.016 60.025

1400. 70.044 69.988 70.043 70.002 70.012

160080.033 79. Q 71 80.036 79.983 79.994

1800 • 90.019 89.950 90.026 89.Q60 89.971

2000 • 100 . 000 99.925 100.013 99.931 99.944

NORMALIZED DIFFERENCES FROM FIRST-NBS CALIBRATION

200. .000 -.010 -.004 -.007 .002

400. .000 -.017 -.006 -.011 -.003

600. .000 -.026 -.007 -.016 -.007

800. .000 -.034 -.007 -.021 -.013

1000. .000 -.042 -.006 -.028 -.019

1200. .000 -.047 -.004 -.035 -.025

1400. .000 -.056 -.001 -.042 -.032

1600. .000 -.062 .003 -.050 -.040

1800. .000 -.068 .007 -.05Q -.048

2000. .000 -.075 .013 -.069 -.056
OMNITAB - COMPARISON WITH FIRST-NBS CALIBRATION

TABLE 5 " CALIBRATION DATA FOR 23 DEGREES C

20*000 LBF MOREHOUSE PROVING RING NO. 193

COMPRESSION

LOAD C T r> C T r I Kb 1 LAB LAB i A O LAB LAB LAB F I N AL

LBF NBS A B c 0 E NBS

SECOND-DEGREE VALUES

2000. 92.63 92.8? 92.85 92.66 92.57 92.51 92.65

1000. 185.57 185.70 185.66 185.68 185.40 185.1? 185.58

6000. 27R.86 278.95 278.85 27°. 06 278.62 278.74 278.87

8000. 372.51 372.58 372.42 372.80 372.23 372.10 372.52

10000. 466.52 466.57 466.38 466.89 466.22 466.42 466.53

12000. 560.89 560.94 560.73 561 .35 560.60 560.81 560.89

11000. 655.61 655.69 655.46 656.16 655.37 655.55 655.61

16000. 750.69 750.80 750.57 751.33 750.52 750 .66 750.69

18000. 846. 13 846.29 846.07 846.86 846.07 846.12 846.13

20000. oil .92 942.15 941 .95 942.75 942.00 941.96 911.93

NORMALIZED CURVE VALUES

2000. 9.834 9.854 9.858 9.837 9.828 9.822 9.836

4000

19.701 19.715 19.711 19.713 19.683 19.688 19.702

6000. 29.606 29.615 29.601 29.627 29.580 29.593 29.607

8000. 39.518 39.555 39.538 39.579 39.518 39.536 39.549

10000. 49.529 19.531 49.514 49.568 49.497 49. 518 49.529

12000. 59.547 59.553 59.531 59.596 59.517 59.539 59.548

14000. 69.601 69.612 69.588 69.662 69.578 69.597 69.604

16000. 79.698 79.710 79.685 79.766 79.680 79.694 79.698

18000. 89.830 89.817 89.824 89.908 89.824 89.830 89.831

20000. 100.000 100.021 100.003 100.088 100.008 100.004 100.001

NORMALIZED DIFFERENCES FROM FIRST-NBS CALIBRATION

2000. .000 .020 .023 .003 -.006 .012 .0 02

inno

.000 .011 .010 .012 -.018 .013 .001

6000. .000 .009 -.001 .021 -.026 .013 .001

8000. .000 .007 -.010 .030 -.030 .012 .001

10000. .000 .005 -.015 .039 -.032 .011 .001

12000. .00n .006 -.017 .019 -.030 .009 .000

11000. .000 .008 -.016 .059 -.026 .006 .000

16000. .000 .012 -.013 . 068 -.018 .001 .000

18000. .000 .017 -.006 .078 -.006 .000 .001

20000. .000 .021 .003 .088 .008 .001 .001
OMNITAB - COMPARISON WITH FIRST-MRS CALIBRATION

TABLE 6 " CALIBRATION DATA FOR 23 DEGREES C

20»000 LBF MOREHOUSE PROVING RING NO. 193

TENSION

LOAD FIRST LAB LAB LAB LAB LAB FINAL

LBF NBS A B C D E NBS

SECOND-DEGREE CURVE VALUES

2000. 92. 18 92. 06 92. 18 92. 1ft 92.14

4000. 184.02 1R3.85 184. 10 184.05 184.00

6000. 275.54 275.33 275.70 275.60 275.53

8000. 366.75 366.50 366.97 366.8? 366.75

i1UUUU nnnn

4S7 £.4 t4S7J ' .• JO"^A 4ft7 - Q"^ aR7 7o 4ft7 A4

548.21 547 • 90 548 . ft6 ft4fl . 3D 54R.21

i u n n n

638.47 638.13 638 . ft 7 638 . 5ft 6^8 . 47

i fif\ n n * JL vJ XJ l ' KJ • 7Pfl . 41 7PR . 05 728 . 86 72ft . 4ft 728 .40

18000

818.04 817 • 65 818 . 53 81P . Oft 818.01

907 . 34 QOft • 95 907 . ftft 907. 3ft 907. 30

NORMALIZED CURVE VALUES

2000. 10.159 10. 146 10.159 10.159 10.155

4000. 20.281 20.262 20.290 20.285 20.279

6000. 30.368 30.345 30.385 30.374 30.367

8000. 40.420 40.393 40.445 40.42P 40.420

100H0

50 .437 50.406 50.469 50.447 50.437

12000. 60.420 60.385 60.458 60.429 60.420

14000. 70.367 70.329 70.411 70.376 70.367

16000. 80.280 ftO.240 80.329 80.287 80.278

18000. 90. 157 90.115 90.212 90.162 90.154

20000 . 100.000 Q9.957 100.059 100.001 99.995

NORMALIZED DIFFERENCES FROM FIRST-NBS CALIBRATION

cUUU . • nnn u u u -.013 -.000 .000 -.004

4000. .000 -.019 .009 .004 -.002

6000. .000 -.023 .017 .007 -.001

8000. .000 -.027 .025 .008 -.000

10000. .000 -.031 .032 .00Q .000

12000. .000 -.035 .038 .OOP .000

14000. .000 -.038 .044 .009 -.000

16000. .000 -.040 .050 .007 -.001

18000. .000 -.043 .055 .005 -.003

20000. .000 -.043 .059 .001 -.005
OMNITAB - COMPARISON WITH FIRST-NRS CALIBRATION

TABLE 7 - CALIBRATION DATA ^OR 23 DEGREES C

20*000 LRF BLH LOAD CELL NO. 82625

COMPRESSION

1 UMU \ X. r\ J 1 I AR IL_ MAR Il— HAnO 1 AR 1 AR r J NHL

i or A Q r nu

c-d

ClJRVF" V/ a 1 l ire

2000

.

4769 . 4775

.

4766 •

1 1 T"7 4772 • 4-763

.

4 7 65

.

1 . "T ~f "X 4773 • t+000 . 9530. 9540. 9525. 9537. 9518. 9528. 9536.

6000. 14285. 14300. 14280. 142^7. 14270. 14285. 14294.

8000. 19036. 19054. 19030. 19051. 19017. 19036. 19046.

10000. 23781. 23803. 23774. 23799. 23760. 23781. 23793.

12000. 28521. 28547. 28^14. 28541. 28500. 28520. 28534.

14000. 33256. 33285. 33249. 33278. 33235. 33253. 33271.

16000. 37985. 38018. 37979. 38010. 37967. 37979. 38001.

18000. 42709. 42746. 42703. 42736. 42694. 42700. , 42727.

20000. 47429. 47468. 47423. 47456. 47418. 47414. 47447.

NORMALISED

2000. 10.055 10. 067 10.049

4000. 20.093 20. 114 20.083

6000 . 30.120 30.150 30. 108

8000. 40.136 40. 174 40. 124

10000. 50.140 50. 187 50. 126

12000. 60.134 60. 189 60.120

14000. 70.117 70. 180 70. 103

16000. 80.089 80. 159 80.076

18000. 90.050 90. 127 90.037

20000. 100.000 100.084 °9. 988

CURVE VALUES

10.062 10.042 10. 046 10.063

20. 109 20.068 20. 089 20.106

30.144 30.086 30. 120 30.137

40.167 40.096 40. 137 40.157

50.178 50.097 50. 141 50.166

60. 178 60.090 60. 133 60.163

70.166 70.075 70. 111 70.149

80.142 80.051 80.077 80.124

90.106 90.018 90. 029 90.087

100.058 99.978 99.969 100.039

NORMALISED DIFFER ENCES FROM FIRST -NBS CALIBRATION

2000. .000 .012 -.006 .007 -.013 -.009 .008

4000. .000 .021 -.010 .016 -.025 -.003 .013

6000. .000 .030 -.011 .024 -.033 -.000 .017

8000. .000 .039 -.012 .031 -.040 .001 .022

10000. .000 .047 -.014 .038 -.043 .001 .025

12000. .000 .055 -.014 .043 -.044 -.002 .029

14000. .000 .062 -.014 .048 -.043 -.006 .032

16000. .000 .070 -.013 .052 -.038 -.012 .035

18000. .000 .077 -.014 .056 -.032 -.021 .037

20000. .000 .084 -.012 .058 -.022 -.031 .039
OMNITAB - COMPARISON WITH FIRST-MRS CALIBRATION

TABLE 8 - CALIBRATION DATA FOR 23 DEGREES C

20r000 LBF BLH LOAD CELL NO. 82625

TENSION

FTR^T r in j I

1 AO 1 AR LAB LAB LAB

LHr MO C Nab c n F NBS

CURVE VALUES

2000 . 4776 • 4780 • 4763. 4775. 4779.

4ono. 9555. 9559. 9542. 9554. 9559.

6000. 14340. 14344. JL "r v> <£ O • 14345.

6000. 19131. 19135. 19116. 19129. 19136.

1 U 0 u u • 2,392 f * 2oH o "3t O ~K O52

2391 P

23932

12000

XC U u u 2fl7?9

28713, 28728

?8734

i unnn

J J J u . 3352033536. J J JtC

iouuu

O O OH 7jo J^U

38333. 38350jf) j J j .

JL O U U U •

tl ^ 1 A 7 43151

43170

a"* 1 7ti

t U U u u . ii7QQ 1 tou U7 . 47975. U7Q96. (I7QQQ H f 777

NfiRMAI T7Fn CURVE VALUES

9 . Q5? 9 . 9A0 9.925 9.949 9 . 959

4000. 19.911 19.918 19.883 19.907 19.919

6000. 29.881 29.889 29.852 29.878 29.890

8000. 39.863 39.872 39.833 39.860 39.873

X10\J 0V 0'J 0.VJ • 49 . fi57 49.867 49.826 49.855 49.868

12000

59.862 59.876 59.830 59.861 59.874

1400069.879 69.898 69.847 69.880 69.892

79 . 90fl 79.931 79.875 79.911 79.922

16000. 89 . 948 89.977 89.915 89.954 89.963

c u U «J u • X

i nnU U 69 nn0 U V w 100.037 99.967 100. 010 100.016

MHRMAI I7FH DIFFERENCES FROM FIRST-NBS CALIBRATION

2000

.000 .008 -.027 -.003 .007

4000. .000 .007 -.028 -.003 .008

6000.000 .008 -.029 -.004 .009

8000. .000 .009 -.030 -.003 .010

10000. .000 .011 -.031 -.002 .011

12000. .000 .013 -.032 -.001 .012

14000. .000 .019 -.032 .001 .013

16000. .000 .024 -.033 .003 .014

16000. .000 .029 -.033 .006 .015

20000. .000 .037 -.033 .010 .016
Table 9 - Standard deviation (normalized for capacity deflection = 100)

of ten values relative to a fitted curve plotted to the equation:

Deflection = A+B (Load )+C (Load) ^ ; and the curve coefficients.

Normalized Curve Coefficients

Laboratory Std. Dev. A B C

ZjUUU iDi riuving Ring No. 144 in Compression

0.040 0.289308 _> • UoJXlU

A 0.0182 0.156 0.289323 4.998xl0~ 6

B 0.0100 0.004 0.289432 4.979xl0" 6

C 0.0103 -0.022 0. 289639 5.017xl0~

6

D 0.0113 0.137 0.289470 5.095xl0"6

J! 0.0184 0.151 0.289562 4 • y jyxj.u

NBS-2 0.0193 0.392 0.289190 5.062xl0~ 6

2,000 lbf Proving Ring No. 144 in Tension

MB C_ 1 Ntto—

A

0.0113 -0.029 0.289260 /, /, i v i A

-

^ — 4 . 'OJ.X1U

A

B 0.0096 0.001 0.289222 -4.514x10

C 0.0113 -0.012 0.289450 -4.366xl0~ 6

D

E 0.0220 -0.359 0.289350 -4.386xl0" 6

NBS-2 0.0111 -0.186 0.289291 -4.392xl0"6
page 2

Table 9 - Standard deviation (normalized for capacity deflection = 100)

of ten values relative to a fitted curve plotted to the equation;

Deflection A+B(Load)+C(Load) 2

; and the curve coefficients.

Laboratory

NBS-1

A

B

C

D

E NBS-2

Normalized

Std. Dev.

Curve Coefficients

B 2,000 lbf Load Cell No. 51841 in Compression

0.0021

0.0080

0.0057

0.0035

0.0018

0.0039

0.0012

- 1.9

7.2

- 2.6

- 0.2

-17.1

1.6

2.5

23.6449

23.6295

23.6404

23.6534

23.6618

23.6337

23.6382

6.0x10

7 . 0x10

4 . 1x10

4 . 1x10

8.2x10

2 . 9x10

3.0x10

-6

-6

-6

-6

-6

-6

2,000 lbf Load Cell No. 51841 in Tension

NBS-1

A

B

C

D

E

NBS-2

NBS-1

A

B

C

D

E

NBS-2

0.0017

0.0103

0.0024

0.0032

0.0032

2.4

2.3

1.4

1.0

4.9

23.6610

23.6401

23.6542

23.6531

23.6529

-23.8x10

-6

-22.1x10

-18.6x10

-6

-6

-27.6x10

-27.0x10

-6

-6

20,000 lbf Proving Ring No. 193 in Compression

0.0040

0.0074

0.0176

0.0051

0.0107

0.0082

0.0086

0.049

0.308

0.429

-0.004

0.125

-0.059

0.073

0.0462011

0.0461612

0.0461152

0.0462420

0.0461257

0.0461956

0.0461980

4.462x10

4.653x10

4.804x10

4.479x10

4.839x10

4.526x10

4.473x10

-8

-8

-8

-8

-8

-8
page 3

Table 9 - Standard deviation (normalized for capacity deflection = 100)

of ten values relative to a fitted curve plotted to the equation:

Deflection = A+B(Load)+C(Load) 2

; and the curve coefficients.

Laboratory

NBS-1

A

BC

D

E

NBS-2

NBS-1

A

B

C

D

E

NBS-2

NBS-1

A

B

C

D

E

NBS-2

Normalized

Std. Dev.

Curve Coefficients

B 20,000 lbf Proving Ring No. 193 in Tension

0.0073

0.0058

0.0062

-0.0069

0.0083

0.022

-0.041

-0.066

-0.016

-0.034

0.0461574

0.0461302

0.0462015

0.0461794

0.0461684

20,000 lbf Load Cell No. 82625 in Compression

0.0025 2.9 2.38431

0.0065 4.4 2.38655

0.0036 0.9 2.38359

0.0018 1.5 2.386741

0.0115 3.4 2.38067

0.0039 -4.5 2.38622

0.0018 4.0 2.38564

20,000 lbf Load Cell No. 82625 in Tension

0.0040 2.4 2.38546

0.0078

0.0029

0.0037

0.0035

6.6

-9.8

1.4

5.0

2.38499

2.38512

2.38517

2.38577

-3.956x10

-3.904x10"

-4.022x10"

-4.054x10"

-4.009x10"

-65.2x10

-66.8x10

-62.4x10

-70.1x10

-49.7x10

-76.5x10

-67.5x10

-8

-8

-8

-8

-8

-8

69.9x10

-8

75.6x10

70.6x10

72.7x10"

69.6x10"

-8
IIiI
2.000L8F RANGE COMPRESSION DATA ONLY

+ 0.i

<

<

u

u.O

z

o

-0.1

<

trCO

<

u

(/) CO

z

I I—

to

cc

2

o

QCu.

UJ

o

z

UJ

a:uj

u.u.

20, 000LBF RANGE

+ 0.1

-0.1

PROVING RING

FIGURE 1

10 20 30 40 50 60

LOAO (% OF CAPACITY)

70 80 90 10.0

Comparison of normalized calibration curves againstv First-NBS

Calibration _ Laboratory A
2,000 LB F RANGE

+0.1 -

20,000 LBF RANGE

-1-0 . i ~t

0.3 J

*

f

' I s i I a 1 i t 0 10 20 W 40 50 60 70 80 90 100

LOAD (% OF CAPACITY)

FIGURE 2 - Comparison of normalized calibration curves against First-NBS

Calibration - Laboratory B
COMPRESSION

TENSION

2,000 LBF RANGE

cr -0.1

2

to

CD

20,000 LBF RANGE

I I I I I I I I I

» » 0 10 20 30 40 50 60 70 80 90 100

LOAD (% OF CAPACITY)

FIGURE 3 - Comparison of normalized calibration curves against First-NBS

Calibration - Laboratory C
2,000 LB F RANGE COMPRESSION DATA ONLY

20.000LBF RANGE

+0.1

0-

-0.I--

PROVING RING

LOAD CELL

L. 0

FIGURE 4

JL 10 20 30 40 50 60 70

LOAD (% OF CAPACITY)

80 90 100

Comparison of normalized calibration curves against First-NBS

Calibration - Laboratory D
2,000 LB F RANGE

COMPRESSION

TENSION

I I I I I I I L_ I I | 0 10 20 30 40 50 60 70 80 90 100

LOAD (% OF CAPACITY)

FIGURE 5 - Comparison of normalized calibration curves against First-NBS

Calibration - Laboratory E
2,000 LBF RANGE

-i»0.

20,000 LBF RANGE

+0

JL 10 20 30 40 50 60

L0A0 (% OF CAPACITY)

70 80 90 100

FIGURE 6 - Comparison of normalized calibration curves against First-NBS

Calibration - Final NBS
N Ob- t I 4 A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 74-462

2. Gov't Accession

No.

3. Recipient's Accession No.

A [* II 1 I. A \ M CI I UTITI U" 4 . 1 1 1 LI. aAU MJP 1 1 1 Lt

Interlaboratory Comparisons of Static Force Calibrations

5. Publication Date June 1974

6« Performing Organ 1 z at ion C ode

7. AUTHOR(S)

R. W. Peterson

8. Performing Organ. Report No. NBSIR 74-462

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WAinlNblUN, U.L.. /(JzJ4

10. Project Task ''Work Unit No. 2130456

11. Contract / Grant No.

DOD/CCG 72-61

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Department of Defense, Calibration Coordination Group

HQ Aero Space Guidance and Metrology Center (AFLC)

Attention: AGL-Mr. Ray Y. Bailey

Newark Air Force Station, Newark, Ohio 43055

13. Type of Report & Period Covered Summary

7-15-71 - 12-31-74

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary ol most significant information. If document includes a significant

bibliography or literature survey, mention it here.)

This report presents a summary of the first phase of a program developed to

intercompare capabilities of DOD calibration laboratories in the parameter of

static force measurement. Comparisons of calibrations were made by normalizing

the data and plotting second-degree curves.

17. KEY WORDS (six to twelve entries: alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons) Force;force calib ration; inter laboratory test;load cell;

proving ring;static force

18. AVAILABILITY |

; Unlimited 19. SECURITY CLASS

(THIS REPORT)

21. NO. OF PAGES

[xX For Official Distribution. Do Not Release to NTIS

UNCL ASSIFIED

23

1 Order From Sup. of Doc, U.S. Government Printing Office Washington. D.C. 20402. SD Cat. No. C13

20. SECURITY CLASS

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22. Price

Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151 UNCLASSIFIED

USCOMM.DC 29042-P74