[Code of Federal Regulations]
[Title 27, Volume 1]
[Revised as of April 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 27CFR30]

[Page 852-853]
 
            TITLE 27--ALCOHOL, TOBACCO PRODUCTS AND FIREARMS
 
 CHAPTER I--ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE 
                                TREASURY
 
PART 30_GAUGING MANUAL--Table of Contents
 
                      Subpart C_Gauging Instruments
 
Sec.  30.22  Hydrometers and thermometers.

    The hydrometers used are graduated to read the proof of aqueous 
alcoholic solutions at 60 degrees Fahrenheit; thus, they read, 0 for 
water, 100 for proof spirits, and 200 for absolute alcohol. Because of 
temperature-density relationships and the selection of 60 degrees 
Fahrenheit for reporting proof, the hydrometer readings will be less 
than the true percent of proof at temperatures below 60 degrees 
Fahrenheit and greater than the true percent of proof at temperatures 
above 60 degrees Fahrenheit. Hence, corrections are necessary for 
hydrometer readings at temperatures other than 60 degrees Fahrenheit. 
Precision hydrometers shall be used for gauging spirits. Hydrometers and 
thermometers shall be used and the true percent of proof shall be 
determined in accordance with Sec.  30.31. Hydrometers are designated by 
letter according to range of proof and are provided in ranges and 
subdivisions of stems as follows:

------------------------------------------------------------------------
             Precision                        Range          Subdivision
------------------------------------------------------------------------
F..................................  0 to 20...............    0.2[deg]
G..................................  20 to 40..............    0.2[deg]
H..................................  40 to 60..............    0.2[deg]
I..................................  60 to 80..............    0.2[deg]
K..................................  75 to 95..............    0.2[deg]
L..................................  90 to 110.............    0.2[deg]
M..................................  105 to 125............    0.2[deg]
N..................................  125 to 145............    0.2[deg]
P..................................  145 to 165............    0.2[deg]
Q..................................  165 to 185............    0.2[deg]
R..................................  185 to 206............    0.2[deg]
------------------------------------------------------------------------

    Thermometers are designated by type according to range of degrees 
Fahrenheit and are provided in ranges and subdivisions of degrees as 
follows:

------------------------------------------------------------------------
                Type                          Range          Subdivision
------------------------------------------------------------------------
Pencil type........................  10[deg] to 100[deg]...      1[deg]
V-back.............................  10[deg] to 100[deg]...      1[deg]
Glass shell (earlier model)........  40[deg] to 100[deg]...  \1/2\[deg]
Glass shell (later model)..........  40[deg] to 100[deg]...  \1/4\[deg]
------------------------------------------------------------------------


[[Page 853]]


(Sec. 201, Pub. L. 85-859, 72 Stat. 1358, as amended (26 U.S.C. 5204))

[T.D. ATF-198, 50 FR 8535, Mar. 1, 1985, as amended by T.D. ATF-381, 61 
FR 37003, July 16, 1996]