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Hard Chrome Plating Training Course

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Appendix 8. Conversion of Degrees Baumé to Concentration for Chromic Acid

Degrees
Baumé (Be°)		 Chromic Acid,
oz/gal		 Chromic
Acid, g/L
1.50 2.10 15.7
2.00 2.80 20.9
2.50 3.40 25.4
3.00 4.10 30.6
3.50 4.80 35.8
4.00 5.50 41.0
4.50 6.20 46.3
5.00 6.80 50.7
5.50 7.50 56.0
6.00 8.20 61.2
6.50 8.90 66.4
7.00 9.70 72.4
7.50 10.40 77.6
8.00 11.10 82.8
8.50 11.90 88.8
9.00 12.60 94.0
9.50 13.40 100.0
10.00 14.20 105.9
19.00 29.00 216.3
19.50 29.80 222.3
20.00 30.60 228.3
20.50 31.50 235.0
21.00 32.40 241.7
21.50 33.30 248.4
22.00 34.20 255.1
22.50 35.10 261.8
23.00 36.00 268.6
23.50 37.10 276.8
24.00 38.20 285.0
24.50 39.10 291.7
25.00 40.00 298.4
25.50 40.90 305.1
26.00 41.90 312.6
26.50 42.90 320.0
27.00 44.00 328.2

The chromic acid concentration of a hard chrome bath can be estimated using hydrometer (Baumé stick) readings. This method is most accurate with fresh plating solutions. For used chrome baths this methods produces higher than actual chromic acid values since it also measures bath contaminants (i.e., trivalent chromium and tramp metals). Therefore, periodic laboratory analyses are also necessary.
Degrees
Baumé (Be°)		 Chromic Acid,
oz/gal		 Chromic
Acid, g/L
27.50 45.00 335.7
10.50 15.00 111.9
11.00 15.80 117.9
11.50 16.50 123.1
12.00 17.30 129.1
12.50 18.20 135.8
13.00 19.10 142.5
13.50 19.80 147.7
14.00 20.40 152.2
14.50 21.20 158.2
15.00 22.00 164.1
15.50 22.90 170.8
16.00 23.70 176.8
16.50 24.50 182.8
17.00 25.40 189.5
17.50 26.30 196.2
18.00 27.20 202.9
18.50 28.10 209.6
28.00 46.00 343.2
28.50 47.10 351.4
29.00 48.20 359.6
29.50 49.20 367.0
30.00 50.20 374.5
30.50 51.50 384.2
31.00 52.70 393.1
31.50 54.00 402.8
32.00 55.20 411.8
32.50 56.30 420.0
33.00 57.50 429.0
33.50 58.70 437.9
34.00 60.00 447.6
34.50 61.20 456.6
35.00 62.30 464.8
35.50 63.50 473.7
36.00 64.80 483.4

To measure Baumé pour a bath sample into a beaker
or graduated cylinder and allow it to cool to room
temperature. Place a hydrometer into the solution and
allow it to float to a steady point. Read the density in
Baumé and use the above chart to convert to chromic
acid concentration in either ounces per gallon (oz/gal) or
grams per liter (g/L).


Appendix 9

 

 

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