ADM003GVAE1005 241
strapping table will also affect the accuracy of the volume calculation. Errors in the
strapping table could appear as leaks.
Some factors have more influence than others, depending upon the application. In
large tanks (over 50,000 gallons), the resolution of the level measurement is the
limiting factor. For example, for a 1,000,000-gallon cylindrical tank, 40 feet in
height, a sixteenth of an inch (1/16”) equates to almost 150 gallons. This means
that a long time period is needed to effectively detect a leak. Another limiting
factor is the resolution and stability of the temperature sensor. Changes in both
the product and the tank shell temperature will affect the volume of the product in
the tank.
Currently, Leak Detection is approved with three different level probes for
volumetric leak detection:
Mass Analysis
Mass based leak detection is based upon measuring the pressure of the product
and applying the conservation of mass principle. In bulk storage tanks, the Total
Observed Volume will fluctuate with changes in the temperature of the product.
The mass of the product in the tank is a constant, so changes in the temperature
of the product have no effect on the total mass in the tank.
Currently, Leak Detection is approved with one probe for mass-based leak
detection:
Manufacturer
& Model
Volume Leak Rate/Test Time
MTS DDA 0-75,000 gallons .2 gal/hr; 24 hour test
L&J 8100 0-75,000 gallons .2 gal/hr; 24 hour test
Barton
Instruments
0-75,000 gallons .2 gal/hr, 24 hour test
Manufacturer Volume Leak Rate/Test Time
Barton Instruments 0-3,000,000 gallons 3.0 gal/hr; 48 hour test
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