Atmospheric behaviour of rolled zinc in eight Canadian atmospheres: summary of ten years' results

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Atmospheric behaviour of rolled zinc in eight Canadian atmospheres:

summary of ten years' results

NATIONAL RESEARCH COUNCIL CANADA

DIVISION OF BUILDING RESEARCH

ATMOSPHERIC BEHAVIOUR OF ROLLED ZINC IN EIGHT CANADIAN ATMOSPHERES

--SUMMAR Y OF TEN YEARS! RESULTS by

H. Guttman and C. A. Hamer

Cominco Limited, Sheridan Park, Ontario and

E. V. Gibbons

Division of Building Research,

National Research Council, Ottawa, Ontario

ANALYZED

A joint report of Cominco Limited and the Division of Building Research,

National Research Council.

Internal Report No. 334 of the

Division of Building Research

OTTAWA November 1966

Information is frequently required on the atmospheric corrosion behaviour of different architectural metals at

various locations across Canada. To assist in overcoming

the lack of published information on this subj ect the form er Associate Committee on Corrosion Research and Prevention (A. C. C. R. P.) of the National Research Council, initiated

a metals exposure program. It was a cooperative undertaking

involving Canadian metal suppliers, users and research

organizations. The first metals were selected in 1953 for

exposure at eight outdoor sites across Canada.

The program included, in addition to the architectural metals, a number of different metal and organic coatings

on steel. This report describes the lO-year performance

of rolled zinc panels. Reports have been issued that describe

the performance of thr ee aluminum alloys and aluminum rivetted bimetallic couples, three stainless steels and

two magnesium alloys. A report covering the behaviour

of three steel alloys will be issued in the near future. The specimens of rolled zinc were furnished by Cominco Limited, Sheridan Park, Ontario, which was also responsible for assessing their performance and

in compiling this report. This part of the study was under

the dir ection of Mr. H. Guttman with the assistance of

Mr. C. A. Harner. The arrangements for exposure and

examination of specimens and SOme over-all co-ordination of the program was carried out under the direction of Mr. E. V. Gibbons of the Division of Building Research.

The Division is indebted not only to the companies who have cooperated in making this study possible, but also to those who have contributed to the provision and servicing of certain of the exposure sites.

Ottawa

November 1966

N. B. Hutcheon. Assistant Director

ATMOSPHERIC BEHAVIOUR OF ROLLED ZINC IN EIGHT CANADIAN ATMOSPHERES

--SUMMARY OF TEN YEARS' RESULTS

by

H. Guttman and C. A. Hamer

Cominco Limited, Sheridan Park, Ontario

and

E. V. Gibbons

Division of Building Research,

National Research Council, Ottawa, Ontario

An outdoor architectural metals exposure program was undertaken by the Associate Committee on Corrosion Research and Prevention to obtain information on their relative atmospheric corrosion behaviour at various

locations across Canada. Details of the program were

planned by Subcommittee IIC" of the Associate Committee, and the exposure of the metals selected was carried out at the outdoor test sites of the Division of Building Research

of the National Research Council. The first group of metals

exposed included specimens of rolled zinc, aluminum and aluminum coupled to copper, zinc and mild steel, thr ee low alloy steels, three stainless steels and two magnesium alloys. This report describes the ten-year performance of the rolled

zinc furnished by Cominco Limited. The other materials

for this part of the program were furnished by the Aluminium Lab'oratories Limited, the Steel Company of Canada Limited, Atlas Steels Company and Dominion Magnesium Limited,

respectively. More recently, specimens of copper, muntz

metals, lead alloys, and monel have been added, as well as a number of different metal and organic coatings applied to steel.

The sp e c irn en s for exposure were 4 by 6 in. in size

and of various thicknesses. They were mounted on racks

fitted with porcelain insulator s to hold them in place at 30 deg

to the horizontal facing south. Normally, twelve specimens

of each type of metal were set out initially at each site. This number enabled three specimens of each type to be removed after exposure periods of one, two, five and ten

years. After identification by a punched-hole system and

weighing, the specimens were shipped by the supplier to the National Research Council for distribution to the sites. After each exposur e period it was usual to photograph

the topside and under side of a specimen typical of each lot

before returning the specimens to the original supplier for cleaning, re-weighing and assessment.

The A. C. C. R. P. was disbanded in 1960, but the test

program was continued by the Division of Building Research.

Progress reports have been prepared by Comin co after the

one-, two- and five-year periods, which describe the

performance of the rolled zinc up to this time (1).

These were is sued in 1958 and 1960 and circulated.

DESCRIPTION OF MATERIAL

The rolled zinc specimens that were exposed measured

4 by 6 by O. lOin. They had the following composition,

per cent by weight: Pb 0.08 Cd 0.002 Cu 0.001 Fe 0.004 and were designated B -8 in the series for identification purposes. DESCRIPTION OF TEST SITES

A complete description of the test sites has been published (2). The following is a brief summary of them along with their site number.

1. Ottawa - This site is located on the easterly city limits

and can be classified as semi-rural.

2. Saskatoon - This is a rural site located on the campus

of the Univer sity of Saskatchewan on the outskirts of Saskatoon.

- 3

3. Montreal - This is an industrial site located on

the roof of a two-storey building of the Canadian National Railways in the Point St. Charles district.

4. Halifax - This is a marine industrial site located

on the roof of a Federal Public building in downtown Halifax, two city blocks from the harbour.

5. York Redoubt - This is a rural marine site located

on the Atlantic coast, seven miles from Halifax.

It is at an elevation of 100 ft about 300 ft from

the ocean.

6. Norman Wells - This is a far northern site located

in the Mackenzie River valley about 90 miles south of the Arctic Circle.

7. Esquimalt (Rocky Point) - This is a marine site

on the west coast at the southeast extremity of Vancouver Island, about 15 miles from the city

of Victoria. It is at an elevation of 50 ft and

about 1500 ft from the ocean.

8. Trail - This is a semi-rural site located at

Birchbank in the Columbia River Valley about 6 miles north of the City of Trail.

All of the sites ar e near weather stations of the Meteorological

Division of the Department of Transport. In addition to these

records being available to assist with the interpretation of the exposure results, the relative level of sulphur dioxide at the sites has been measured using the lead peroxide

instrument. This method does not measure the volumetric

concentration of S02 in the atmosphere directly, but presents an integrated measure of the sulphur dioxide "activity" during

a period of exposure. The measurements were made on

a monthly basis. The results have been condensed and

the average level during the ten-year exposure of the

rolled zinc is given in Table I. A graphical representation

of the average concentration of sulphur dioxide during

EXPERIMENT AL PROCEDURE

After the completion of each exposure period the specimens were recalled by NRC, checked, photographed

and then forwarded to Cominco. The specimens were examined

visually, then cleaned of corrosion product, and weight losses and penetration rates were determined. Most of the cleaning of the differ ent lots was carried out using ammonium chloride solution. Its composition and the cleaning procedure are given in Appendix A. The only exceptions to the use of this solution wer e with certain of the lot 3 specimens from sites Nos. 4, 5, 6, 7 and 8, when the suitability of a mixture of chromic acid, silver chromate and strontium chromate and an ammoniacal ammonium acetate solution was investigated. The latter solution was used on the site 4 panels for initial cleaning to r ernove

the excessive foreign deposits present. Sub s equent cleaning cycles on these panels were carried out in the ammonium chloride solution. The chromate solution was used on the specimen 3 panels from sites Nos. 5, 6, 7 and 8 mainly to indicate the suitability of this cleaning agent, particularly in cases where the building of foreign dep os it s on the panels was negligible.

EXPERIMENT AL RESULTS

The appearance of the three specimens of lots one and two from each site was very similar and different from the panels from the other sites. The colour and pattern of the corrosion products and for eign deposits were unique for each site varying from the still shiny, almost uncorroded panels from Norman Wells (site No.6) to the black sooty panels from Halifax (site No.4). The colour transpar encies taken after each exposure period indicated that, in general, this

remained so throughout the ten-year period. Examination

of the panels after cleaning indicated that corrosion was substantially uniform. Minor signs of pitting only in the areas adjacent to the supporting insulators on the more heavily corroded panels were observed after five years of exposur e. After ten year s , pitting had only occurr ed at the more corrosive sites. Corrosion appeared to be more severe on the topside faces than on the underside at all sites.

- 5

The average penetration rates calculated from the corrected weight losses of three specimens per site are

summarized in Table II. The weights, weight losses,

cleaning corrections, corrected losses and penetration rates for the individual specimens from each lot and site

are given in Appendix B. As indicated in Table I I, there

is a large spread in the penetration rates from site to site. At Halifax, which is the most corrosive site, the penetration

rate is more than 100 times that at the least corrosive site,

Norman Wells. The S02 content of the atmosphere appears

to be a critical factor affecting the corrosion of zinc. The

ranking of the sites in severity of corrosion is in the same general order as the S02 level given in Table I. with two

exceptions - - York Redoubt and Es qui.ma.It,

When the five-year results were compiled. in an effort to obtain a clear er under standing of the significanc e of the corrosion rate changes indicated in Table I I, the penetration rate data for all panels exposed during the three exposure periods were analysed by the Cominco

Statistics Group. The findings show that the decreases

in the rates are true decreases at sites Nos. 2, 4, 5, 6

and 7. At site No.8 the differences between panels

within groups were so great that the rate decrease noted

is considered to be due to chance alone. The findings

also show that the rate increases at sites Nos. 1 and 3

are true increases. The corrosion rate decrease at

site No.4 is probably due to the protective action of the relatively heavy foreign deposit that built up on the panels and a decr ease in the S02 content of the

atmosphere during the test period at the site. At

sites Nos. 2, 5, 6 and 7 the corrosion rate decrease

is probably due to the pretective action of corrosion

products formed which remained in situ. The increases

at sites Nos. 1 and 3 could be caused by an increase in the aggressiveness of the atmosphere in question and/or the fact that the panels may be subjected to greater

amounts of precipitation than at the other sites. This

would tend to wash away corrosion products formed. thus making their protective action less effective. A study of the meteorological data does indicate that annual precipitation at Ottawa and Montreal is greater than at all other sites except the two at Halifax.

Figures 2 and 3 show graphs of panel weight loss with

exposure time for each site. For all practical purposes.

these are straight lines indicating that there is little build-up of protective films of corrosion product on zinc panels.

Site No. 4 is the exception; here the corrosion rate was relatively high for the first few years and then decreased

to a fairly constant level. The bar graphs of Figures 4 and 5

also show how these corrosion rates change with time. CONCLUSIONS

1. The Halifax site was by far the most aggressive

atmosphere in the performance of the rolled zinc.

2. Some pitting occurs at the more corrosive sites.

3. The rate of corrosion decreased with time at

all of the sites except Montreal and Ottawa. At these two

sites there was a slight increase in the rate which became fairly constant at Montreal after ten years of exposure.

4. Corrosion appeared to be more severe on the

topside faces than on the under side at all sites.

5. The chromate cleaning method is well suited

for cleaning specimens that are free of a foreign deposit build-up.

REFERENCES

1. The corrosion behaviour of major architectural

and structural metals in Canada: Summary of two year

results. National Research Council, Ottawa, Associate

Committee on Corrosion Research and Prevention. 24 February 1959.

2. Gibbons, E. V. Outdoor exposure sites of the

National Research Council. Chemistry in Canada,

Vol. 12, No.3, March 1960, p. 44-48, (NRC 5593).

TABLE I

AVERAGE AMOUNT OF SU LPHUR DIOXIDE

IN THE ATMOSPHERE AT E;ACH SITE FROM 1955-1965 2

Site No. Location Mg of S03/dm /day

1. Ottawa 0.52 2. Saskatoon O.13

3.

Montreal 1. 61

4.

Halifax 5. 13 5. York Redoubt 0.25 6. Norman Wells 0.01 7. Esquimalt 0.06 8. Trail 0.72

AVERAGE PENETRATION RATES - rn , p. y.

Exposure Site 1 year 2 years' 5 years' 10 yearSl

exposure exposure exposure exposure

1- Ottawa 0.045 0.047* 0.050 0.055 2. Saskatoon 0.025 0.017 0.015 0.011 3. Montr ea.l 0.110 O. 114 O. 131 0.130 4. Halifax 0.916 0.851 0.716 0.532 5. York Redoubt 0.076 0.067 0.055 0.055 6. Norman Wells 0.014 0.009 0.005 0.005 7. Esquimalt 0.027 0.020 0.019 0.017 8. Trail 0.082 0.078 0.074 0.074

5.0

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7

6

FIGURE 1

AVERAGE AMOUNT OF SULPHUR DIOXI DE IN THE ATMOSPHERE AT'EACH SITE 1955-1965

10

9

8

7

6

5

4

3

2

1

o

7

CD

Ottawa

®

Saskatoon

- J

CD

Montreal

LLJ

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c(

York Redoubt

c,

-

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Norman Wells

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Esquimalt

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Tra i I

0 - J

4

I -:::I: ｾ LLJ

3

:i=

LLJ ｾ c( a::::

₂

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1

EXPOSURE TIME, YR

FI GURE

2

WEIGHT LOSS VS TIME EXPOSED FOR ROLLED ZINC

EXPOSED AT TEST SITES INDICATED

35

ｾ

30

LI.I Z

«

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1

2

3

4

5

6

7

EXPOSURE TIME, YR

8

9

10

FIGURE 3

WEIGHT LOSS VS TIME EXPOSED FOR ROLLED ZINC

EXPOSED AT HALIFAX

_./1.

OTTAWA

0.4

ESQUIMALT

->=

_.

0.2

-a..

_.

:E

--

0

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2 5 10

1 2 5 10

YEARS OF EXPOSURE

FI GURE

4

ATMOSPHERIC CORROSION RATE OF ROLLED

ZINC EXPOSED FOR 1, 2, 5 AND 10 YEARS

AT OTTAWA, ESQUIMALT, SASKATOON AND

3172-4-1.0

0.8

0.6

· 0.4

>-·

a.

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TRAIL

0.4

0.2

YORK

REDOUBT

1 2 5 10

1 2 5 10

YEARS OF EXPOSURE

FI GURE

5

ATMOSPHERIC CORROSION RATE OF ROLLED

ZINC EXPOSED FOR 1, 2, 5 AND 10 YEARS

AT HALIFAX, MONTREAL, TRAIL AND YORK

Cleaning Rrocedure

1. Scrub with water and detergent using a soft bristle brush to r ernov e loose corrosion products.

2, Immerse in well-stirred, 10% NH

4Cl solution at 60°F for 5 min.

3. Scrub with soft bristle brush under running hot water. 4. Hot air dry.

5. Weigh.

6. Repeat steps 2 through 5 until

a

constant weight loss/cycle is obtained (and until examination under low magnification reveals that all corrosion products have been removed).

The cleaning loss/cycle is the constant loss obtained

after corrosion products have been removed. The corrected

weight loss is the total weight loss minus the (cleaning loss/cycle x the numb er of cycles).

Corrosion Rate

The penetration rate in mil per year was calculated by use of the following formula:

mpy

=

Corrected weight loss (gm) x

8.

55

Specimen area (s q in.) x Exposure time (Yl'l) Specimen area is 50 sq in. including edges.

Cleaning Solution Used

(1) Ammonium Chloride Solution (Uhlig, H. H. The Corrosion

Handbook, John Wiley and Sons, Inc., N. Y., p. 344). 10%

Balance.

Panels are immersed in this solution at 60°C, with agitation for 5 min/cycle. The cleaning loss/cycle is obtained by repeating cycles until a constant weight loss is attained. The cleaning correction (0.019 gm/cycle) is then subtracted from the total weight loss determined.

A - 2

(2) Chromate Mixture (E. G. Straud, J. App l, Chern.

1951, 1, p. 93). Balance Cr0 3 AgCr0 4 SrCr0 4

H

2

°

10% 2% >19% }

greater than solubility limit )

Panels are immersed in this mixture at r oorn temperature for 20 min. on the first cycle and 5 min. on subsequent cycles. Adequate stirring must be provided to keep the excess of AgCrO 4

and SrCr04 in suspension. Cleaning cycles are continued until

the weight loss/cycle is negligible.

(3) Ammoniacal Ammonium Acetate Solution

(Formulation based on Cominco Laboratory experience). NH

40H (28%) - 4 parts by volume

H

20 - 4 parts by volume

Glacial Acetic

Acid - 1 part by volume

Panels are immersed in this solution at room temperature

with agitation. It was used during the fir stcleaning cycle of

site 4 panels. Subsequent cleaning was carried out with solution

(1). The cleaning correction of 0.027 gm/cycle was determined

after constant weight loss/cycle with the ammonium chloride solution was attained.

Corrosion Rate Calculation

The penetration rate in mil per year (rnpy) was calculated

using the following formula:

mpy

=

Corrected weight loss (gm) x 8. 55

Specimen area (sq in.) x Exposure time (yr) Specimen area is 50 sq in. including edges.

WITH TIME OF P.XPlliUR!':

B-8 ROLLED ZINC -

wr

1 - EXFOSED 1 YEAR

Original Vito After Cleaning Corrected Penetration Site Specimen Wt., Cleaning Wt. Loss. Correction.. Wt. Loss. Rate,

•

ｾ No. gm gm --&!!i_ gm gm mpy

1 1 285.124 284.830 0.294 0.015 0.279 0.048 2 285.136 284.858 0.278 0.015 0.263 0.045 3 284.280 284.013 0.267 0.015 0.252 0.043 Ave. _{<:2_.045)} 2. 1 288.485 288.325 0.160 0.015 0.145 0.025 2 288.862 288.702 0.160 0.015 0.145 0.025 3 290.978 290.816 0.162 0.015 0.147 0.025 Ave. ｾ 3. 1 287.227 286.568 0.659 0.015 0.644 0.110 2 290.722 290.066 0.656 0.015 0.641 0.110 3 287.335 286.670 0.665 0.015 0.650 0.111 Ave.

_ｾ

4. 1 287.609 282.052 5.557 0.030 5.527 0.945 2 288.815 283.448 5.367 0.030 5.337 0.912 3 290.108 284.871 5.237 0.030 5.207

etm

Ave. _ｏＮｾ 5. 1 288.301 287.842 0.459 0.015 0.444 0.076 2 285.892 285.431 0.461 0.015 0.446 0.076 3 287.024 286.573 0.451 0.015 0.436

ｾ

Ave. 0.076"I 6. 1 291.450 291.327 0.123 0.015 0.108 0.018 2 284.777 284.694 0.083 0.015 0.068 0.012 3 287.648 287.550 0.098 0.015 0.083

ｾ

Ave. _{0. 01}

₉

7. 1 285.269 285.084 0.185 0.015 0.170 0.029 2 285.497 285.334 0.163 0.015 0.148 0.025 3 287.485 287.3"11.7 0.168 0.015 0.153

ｾｾ

Ave 0.02'0 8. 1 292.297 291.751 0.546 0.015 0.531 0.091 2 290.623 290.120 0.503 0.015 0.488 0.083 3 285.324 284.885 0.439 0.015 0.424 0.072 Ave. _CQ.08S'.

B-2'

B-8 ROLLED ZINC - LOT 2 - EXPOSED 2 YEARS.

Original Vit. After Cleaning Corrected Penetration

Site Specimen Wt. , Cleaning, Vit. loss, Correction

_,

Wt. loss. Rate,

ｾ

No.

gm gm gm gm gm ropy 1. 1 291.691 291.118 0.513 0.030 0.543 0.046 2 291.851 291.261 0.590 0.030 0.560 0.048 1 3 285.734 284.521 1.213 0.030 1.183 0.1011 Ave. CQ..041.) 2 2. 1 281.810 281.592 0.218 0.030 0.188 0.016 2 288.231 288.010 0.221 0.030 0.191 0.011 3 281.897 287.656 0.241 0.030 0.211 0.018 Ave.

ｾ

3. 1 292.314 291. 012 1.362 0.030 1.332 0.114 2 292.191 290.816 1.381 0.030 1.351 0.116 3 291. 899 290.553 1.346 0.030 1.316 0.112 Ave.

_ｾ

4. 1 289.924 280.085 9.839 0.030 9.809 0.839 2 289.876 280.010 9.866 0.030 9.836 0.841 3 290.405 280.113 10.232 0.030 10.202

ｾ

Ave. 0.85 5. 1 286.808 286.002 0.806 0.030 0.116 0.066 2 281.321 286.491 0.824 0.030 0.194 0.068 3 281.863 281.063 0.800 0.030 0.710 0.066 Ave.

ｾ

6. 1 284.614 284.553 0.121 0.030 0.091 0.0018 2 285.445 285.314 0.131 0.030 0.101 0.0086 3 285.981 285.842 0.145 0.030 0.115

o

0098 Ave.

C§::

OOBjo"

1. 1 285.200 284.914 0.286 0.030 0.259 0.022 2 284.951 284.691 0.254 0.030 0.224 0.019 3 284.220 283.951 0.269 0.030 0.239 0.020 Ave.

<[;02Q::

8. 1 291.659 290.735 0.924 0.030 0.894 0.016 2 292.001 291.083 0.918 0.030 0.888 0.016 3 284.096 283.111 0.985 0.030 0.955 0.082 Ave.

_{｀ＮｾＷｾ}

1. Wt. loss too high

-

error in original wt.7

B-8 ROLLED ZINC -- LOT

3 --

EX.! OSED

5

YEARS

- - - _.. _-_.-.

Original lit. After Cleaning Corrected Penetration

Site Specimen Ht., Cleaning, '-it. Loss, Correction, Wt. Loss

,

Rate,

No. No. gm _BIll gm Qn &n roPy

1

1

293. 127

291.610

1.517

0.057

1.lK>0

0.050

2

291. 590

290.084

1.5c6

0.057

1.449

0.050

3

2&>.995

285.443

1.552

0.057

1.495

0.051

Average

0.050

2

1

287.840

287·382

0.458

0.057

0.401

0.014

2

288.454

287.969

0.485

0.057

0.428

0.015

3

288.600

288.104

0.496

0.057

0.439

0.015

Average

0.015

3

1

287.126

283.255

3.871

0.057

3.814

0.130

2

291.952

288.000

3.952

0.057

3.895

0.133

3

291.705

287.888

3.817

0.057

3.760

0.129

Average

0.131

4

1

290.8 15

269.296

21·519

0.103

21.416

_0·735

2

289.681

268.920

20.761

0.103

20.658

0.707

j

289.501

268.776

20.725

0.103

20.622

0.706

Average

0.716

5

1

285.2 03

283.560

1.643

0.038

1.605

0.055

2

285.223

283·551

1.672

0.057

1.615

0.055

3

2&>.658

285.052

1.606

Nil

1.6c6

0.055

Average

0.055

6

1

284.445

284.270

0.175

0.038

0.137

0.0047

2

2e6·312

286.112

0.200

0.057

0.143

0.0049

3

284.163

283.992

0.172

Nil

0.172

0.0059

Average

0.0052

7

1

284.lK>7

283.913

0·554

0.038

0.516

0.018

2

284.509

283.900

0.609

0.057

0·552

0.019

3

292.673

292.081

0·592

Nil

0.592

0.020

Average

0.019

8

1

283. 832

281.660

2.172

0.057

2.115

0.072

2

285. 162

282.878

2.284

0.057

2.227

0.076

3

287.220

.285.514

1.7c6

Nil

1.7c6

0.058

Average

0.074*

*

_{Average of GpeC1mens}

.

₁

_and

₂

_{only. Error suspected in recording}

B-4

ll-R IWLLlW ZINC - LOT 4 - EXJ-'OSED 10 YEj,RS

Odrdnnl Vlt.

;·n

er lIt. Gler:ninp: Corrected Fenet ....ation

Sit'? Spec irien 1,1+ _{C1p;mi'w, Loss, co"....ect.i.on, \it. Loss fld,e,}

'I!.1• J 1.c. No. (;nl pm gm gm gm mry ＭＭＭＭＭＭｾ｟ＮＬＭＭＭＭ ,ＮｾＮＭＮＭ ---,,---

--

..

--_._-_._.,,_._---1 l.

292.971

289·692

3.279

0.0;15

_3.245

0.055

2

288.668

_285·370

_3.298

0.0)5

3.262

0.056

. /

?9

i.462

288·355

3·107

0.0;6

3·071

0.053

2

1

285.0

1f5

₂₈

Lf.

₎₄₄

_0·700

_0.036

_0.664

_{o. on}

2

2')0.057

289·317

0.704

0.036

0.668

o.cn

3

287.822

287·072

0·750

0.0;6

0.714

0.012

3

28';.2)S

281. 607

7.651

0.059

7.592

0.1)0

r,

:::87.553

279·915

7.64]

0.039

7·604

0.1)0

c. ;)

_287.697

_280.091

_7.606

_0.039

_7·567

_0.1.29

4

1

286·905

257·587

29. )J8

0.272

29.0

1+6 _0.496 r,

289·1f16

257·235

)2.193

0.272

3;'.921

0.546

Co )

290.924

258.298

32.626

0.272

32· 354

0.553

5

285.465

282.094

3·27i

o.ovt

3·224

0.055

2

c:85. 1146

282·1.92

3.254

0.047

3·207

0.055

3

288.1+ 16

285.187

3·229

0.047

3·282

0.056

6

J

287.165

286.837

o.

)28

0.029

0.299

0.005

2

287.687

287·349

0·3::8

0.029

0·309

0.005

3

286·900

286.573

_0·327

0.029

0.298

0.005

7

1

284.688

28}.644

1.044

0.048

_0·996

0.017

2

ｾＮＺＸＹＮ

538

288.498

1.

ouo

0.048

0·992

0.017

"

287·980

ｾｂＶＮＹＶＷ

].0

13

0.048

_0·965

0.017

./ 8

285.248

280.990

4.258

0.069

4.189

0.072

r,

285.133

280.540

4.593

0.069

4.

ＵＲＱｾ

0.077

L.

3

284.726

280.450

4.270

0.069

4.201

0.072