PART B - CHECKING PROCEDURES USED TO OBTAIN THE
TEMPERATURE OF PETROLEUM PRODUCTS
Temperature Measurement. Because the volume of petroleum products increases or decreases in
direct proportion to temperature increase and decrease, accurate measurement of the temperature of a
product must be taken at the time of gaging. The measured quantity must be corrected to the standard
temperature of 60F for volumes over 3,500 gallons. When gaging large quantities, take temperature
readings at various levels and average them to determine the true average temperature of the product.
Table 3-1 of FM 10-67-1 (Concepts and Equipment of Petroleum Operations) (Figure 6-4) shows the number
of readings necessary and the levels at which tank thermometers should be placed.
Minimum Number of
Depth of Product
Temperature Measurements
Measurement Levels
More than 15 feet
3
3 feet below top surface of product,
middle of product, and 3 feet above
the bottom
10 -15 feet
2
3 feet below top surface of product,
and 3 feet above the bottom
Less than 10 feet
1
Middle of product
Figure 6-4. Petroleum product temperature measurements (FM 10-67-1, Table 3-1 extract).
Measuring Instrument. The cup-case thermometer (Figure 6-5) is used to measure the temperature of
a product in storage tanks. The thermometer is attached to a hardwood backing with the base of the mercury
column extending into the cup case. The cup case, when filled with liquid under measurement, minimizes
fluctuation of the reading when the thermometer is suddenly withdrawn from the tank. The minimum
immersion time for the cup-case thermometer in various petroleum products is given in Table 3-2 of FM 10-
67-1 (Figure 6-6). To avoid the long immersion time required for measuring the temperature of heavy fuel
oils, it may be practical to leave thermometers suspended in the tanks at all times.
Figure 6-5. Cup-case thermometer.
6-5
QM 5097
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