signals the user when volume data is invalid. For example, loss of temperature data or
gauge input data that exceeds allowable limits for API table entries would cause invalid
volume data. Additional information on error messages and the use of the keypad to dis-
play different types of volumetric data can be found in the PROGRAMMING section of
this manual.
Volume Calculations
1. GOVP = TOTVOL - INTVOL (two float system)
GOVP = TOTVOL (one float system)
GOVI = INTVOL (two float system)
GOVT = GOVP + GOVI (two float system)
GOVT = GOVP (one float system)
GOVU = WORKING CAPACITY - GOVT (one or two float system)
The gross observed volume of the product (GOVP) is equal to the total volume of the
tank (TOTVOL) minus the interface volume (INTVOL). The TOTVOL is measured by the
product float (the float closest to the flange of the gauge) and the INTVOL is measured
by the interface float (the float closest to the tip of the gauge). The level information
from the gauge is used along with the tank gauging table or tank equations to calculate
the corresponding gross observed volumes.
2. NSVP = GOVP x VCF
The net standard volume of the product (NSVP) is equal to the gross observed volume of
the product (GOVP) multiplied by the volume correction factor (VCF). The VCF is calcu-
lated from thermal expansion properties of the product (programmed by the user) and
the temperature information from the gauge. See item #4 below.
3. MASS = NSVP x DENSITY
The mass of the product (MASS) is equal to the net standard volume of the product
(NSVP) multiplied by the density of the product (DENSITY) programmed by the user.
4. VOLUME CORRECTION FACTOR
VCF = EXP {- A(T) x (t-T) x [ 1 + (0.8 x A(T) x (t-T)) ]}
Where:
t = any temperature*
T = base temperature (60 degrees F)
A(T) = coefficient of thermal expansion at base temperature T
Where:
EXP is the exponential function (e
x
).
The coefficient of thermal expansion at the base temperature T is related to the density of
the product at the base temperature T by:
A (T) = [ K0 + K1 x DEN (T) ] / [ DEN (T) x DEN (T) ]
Where:
Density is defined in units of KG/M
3
K0 and K1 are constants related to each product.
* API 2540 states that temperature data is rounded to the nearest tenth (0.1) degree.
5
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