Varec, Inc. 49
Chapter 3
Operation
Initial Operation
Caution Initial filling of the tank must be a reduced rate of flow, until the float travel and
sight indicator operation are verified. This checks that the installation was correctly made
and prevents possible damage to the gauge system. On floating roof tanks this is particu-
larly important because the tape/cable travel has not been checked during the installation.
1. Station an observer at the gaugeboard.
2. Begin filling the tank to raise the float several feet (about three feet or one meter) from
the bottom.
3. Continue filling the tank to the desired level.
4. Hand gauge the product and compare the measurement with the gaugeboard indication.
If they do not coincide, adjust the cable at the indicator or connector plate. Use the spare
cable crimp, if necessary.
Normal Operation
When the tank is full, the indicator is at the bottom of the gaugeboard. As the liquid is removed
from the tank, the float falls and the indicator rises.
Calibration and Volume Measurement
Tank gauging measurements provide appropriate inventory checks and a valuable method of
checking marine receipts and metered custody transfers. Accuracy of measurements requires
that a number of factors be considered:
• Density and specific gravity of product as determined from representative samples
• Sediment in the tank
• Water content in the product
• Gross volume
• Temperature of the product
• Tank-bottom deformation
It is the user's responsibility to appropriately consider these and other factors in his
application. For example, oil tank capacity tables are calculated for product at 60° F. A higher
temperature will cause the tank to expand and the actual volume will be greater than the
volume at the standard temperature.
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