[Code of Federal Regulations]
[Title 27, Volume 1]
[Revised as of April 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 27CFR30.22]

[Page 737-738]
 
            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

[[Page 738]]

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.
------------------------------------------------------------------------


(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]