Three temperatures taken at the middle of the upper, middle, and lower thirds are required for: Tanks with more than a 6m (20 feet) depth of liquid. When temperature differentials greater than 1 ° C (2 ° F) are found, additional temperatures should be taken. The number of temperatures will vary with the temperature differential. However, they must always be equally spaced and averaged accordingly. Very large temperature differentials should be reported to your supervisor; this is indicative of nonhomogeneous material. It is a good work practice to estimate the anticipated temperature of a tank that has received product. This should be based upon the temperature of the material in the tank prior to transfer and the temperature of the material being put into it. A good Inspector always has an approximate idea of the anticipated temperature. If the observed reading differs significantly from the anticipated reading, then the reasons for this difference should be investigated.
4.6 Conclusion Temperatures Make sure your thermometer is field checked and calibrated. Take the appropriate number of temperatures for the amount of material in the tank. Always allow the thermometer to reach equilibrium by raising and lowering it at least one foot. Always, always, always ground your "thermoprobe" prior to opening the tank gauge hatch.
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