METHODS OF SAMPLING AND TESTING HIGHWAY MATERIAL; 
-A 
the central shaft in which the tins 
(A recommended form of aluminum 
of the thermometer without opening the door. It shall also be provided with 
' a perforated circular shelf preferably of approximately 24.8 centimeters (9.75 
i inches) in diameter. This shelf shall be placed in the center of the oven 
and shall be suspended by a vertical shaft and provided with mechanical means. 
for rotating it at the rate of five to six revolutions per minute. It shall be 
provided with recesses equidistant from 
containing the samples are to be placed, 
shelf is shown in fig. 24.) 
3. The thermometer shall conform to the following requirements. These 
specifications cover a special thermometer graduated in centigrade degrees, the 
range being 155 to 170° C. 
Type: Etched stem, glass. 
Liquid : Mercury. 
Range and subdivision: 155 to 170° C. in 0.5° C. 
Total length: 150 to 154 millimeters (5.90 to 6.06 inches). 
Stem : Plain front, enamel back, suitable thermometer tubing. Diameter, 
6 to 7 millimeters (0.24 to 0.28 inch). 
Bulb: Corning normal or equally suitable thermometric glass. Length, 10 t> 
15 millimeters (0.39 to 0.59 inch). Diameter. 5 to 6 millimeters (0.196 to 0.236 
inch). 
Distance to 0° C. line from bottom of bulb: 33 to 38 millimeters (1.30 to 1.49 
inches). 
J.k 
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■Position 
of Boxes .. 
■%< <fC '*** 2 H**£g'"~-± Nut, St'd. 
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Section A-B. 
Thds. 
9 Hoies and Ribs 
Spaced Equally 
Top View 
Fig. 24. — Aluminum shelf 
Distance to 155° C. line from bottom of bulb : 70 to 80 millimeters (2.75 to 3.15 
inches ) . 
Distance to 170° C. line from top of thermometer: 20 to 30 millimeters mi. 7:) 
to 1.18 inches). 
Contraction chamber: To be long, narrow type, top to be not more than 65 
millimeters (2.56 inches) above bottom of the bulb. 
Expansion chamber: To permit heating the thermometer at least 25° C. above 
the highest temperature on the scale. 
Filling above mercury: Nitrogen gas. 
Top finish : Glass ring. 
Graduation : All lines and figures clear cut and distinct. Each whole degree 
centrigrade line to be longer than the remaining lines. Graduations are to be 
numbered at 0°. 155% 163% and 170° C. 
Immersion : Total. 
