Page 68

FIGURE 1

ALCOHOL DILUTION TABLE REDUCTION TABLE [DILUTION OF ALCOHOL TO LOWER STRENGTHS]

DESIRED STRENGTH

STRENGTHS TO BE REDUCED (% V/V) 95%

90%

85%

80%

75%

70%

65%

60%

55%

50%

45%

40%

35%

30%

25%

20%

15%

VOLUME UNITS OF PURE WATER TO ADD TO EACH 100 VOLUME UNITS OF ALCOHOL

% V/V 90% 85% 80% 75% 70% 65% 60% 55% 50% 45% 40% 35% 30%

6.41

25% 20% 15% 10%

13.33

6.58

20.9

13.8

6.83

29.5

21.9

14.5

7.2

39.1

31.0

23.1

15.3

7.64

50.2

41.5

3.0

24.6

16.4

8.15

63.0

53.6

44.2

35.4

26.5

17.6

8.76

78.0

67.8

57.9

48.0

38.3

28.6

19.0

95.9

84.8

73.9

63.1

52.4

41.7

31.1

20.5

10.4

118

105

93.3

81.3

69.5

57.8

46.0

34.5

22.9

11.4

144

131

117

104

90.8

77.6

64.5

51.4

38.5

25.6

179

163

148

133

118

103

88.0

73.0

58.3

43.6

29.0

14.4

224

206

189

171

154

136

119

102

85.0

67.5

50.5

33.5

16.7

287

266

245

224

204

183

162

142

121

101

80.4

60.2

40.0

20.0

382

356

330

304

278

253

227

201

176

150.6

125.2

100

75.0

49.9

24.9

540

505

471

437

403

369

335

301

267

234

200

166.4

133

96.7

66.4

33.2

855.6

804

753

703

652.2

602

551

500.6

450.2

400

350

300

249.4

199.4

150

100

9.5

12.7

50

Alcohol: water mixtures are non-volume additive mixtures. This table may be used to determine the volume of water needed to reduce known volume strengths of alcohol solutions (such as distilled spirits for sensory evaluation or the cutting of spirits to desired final strengths) to desired volume/volume strengths.

is an apparent unresolved assumption here, noted when examining the cancellation of the units – it ends with mass terms (grams) not volume (mL) as illustrated above. However, it is noted for most purposes that the “relative density” of water at unity (at 4 °C) is considered to be 1.0000. Density and gravity relationships are more complex than this but the explanation just given should be acceptable and apparently has been so within the industry for some time. Update: just prior to submission of this manuscript a personal communication from Harvey Wilson (see acknowledgments) showed the relationships proving our simple statement above regarding the relative density of water. A full account is available upon request and will form a part of the ongoing discussion on this important topic. Equation 5 may be rewritten (simplifying to use one equation) as:

TION EQUA

Plugging the requisite values (the same example numbers used above) into the variant equations (7) leads again to 144 units (mL, Liters, Gallons, etc.) of water to be added to 100 units of 95% alcohol. Taking a look at Figure 1 shows that for diluting 95% ABV alcohol solution to 40% ABV, the result is in agreement: the table in Fig. 1 shows 144 parts water to add to 100 parts of 95% ABV solution. The use of such equations and the OIML tables will assist in defining precise dilutions for the distiller. However, Dave Pickerell advised in a meeting in February 2015 that barrel to bottling proof adjustments should be done in two or three defined sub-steps so as not to overshoot the mark. A series of refined dilution steps will get the distiller closer to the required value than one attempted larger single dilution step. This is important to note because reconstituting the spirit solution back to a higher alcohol concentration is even more difficult to calculate and achieve than a dilution (see Addendum for more on this topic). Furthermore, consultants would advise to do all dilutions in the distillery based on weight so accurate balances and means to determine tank weights and weight of water and alcohol would be required. The above equations provide a decent volumetric approach perhaps for smaller scale or beginning operators, with the volumetric evaluation still relying on the “more accurate” underlying mass relationships. Setting up spreadsheets can render the calculation processes quite simple and rapid.

6

y water =

% v/v conc. % v/v dilute

×

V conc. × ρ dilute – Vconc. × ρ conc.

A simpler way to compare data for water of dilution additions is by consulting tables such as ours (see Figure 1), or to prepare solutions of known final volume. The volume of the concentrated alcohol can be set as 100 parts; from this point it is easy to determine the volume units of water to add:

ION 7 EQUAT

y water = 100 × 68 

% v/v conc. × ρ dilute – %v/v conc. × ρ conc. % v/v dilute

(

= 100 ×

% v/v conc.

% v/v dilute

×

)

ρ dilute – ρ conc.

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Artisan Spirit: Spring 2016  

The magazine for craft distillers and their fans.

Artisan Spirit: Spring 2016  

The magazine for craft distillers and their fans.