Max Machinery 121 INDICATOR - Manual (Page 41)

121-000-350 © 2001 Max Machinery, Inc. Pg 41
7.4 Calculating the Expansion Factor
Calculating
Expansion Factor
Two temperature-specific gravity pairs will be required to compute the temperature coefficient.
The reference temperature is simply chosen by the user. Common reference temperatures are 60 F or 15 C.
The reference temperature should be chosen so that it is in the application temperature range. (ex. application
temperature range -10 to 120 F, reference temperature of 60 F chosen.)
Enter the reference temperature you have chosen at this point.
The reference specific gravity corresponds to the fluid SPECIFIC GRAVITY at the reference temperature
chosen.
You may convert the fluid density information to specific gravity if it is in units other than specific gravity. Use
EQ1.
CAUTION: Since the expansion factor is based on a per degree change in temperature, the temperatures used in
the following equations must match (Fahrenheit or Centigrade) the units used on the indicator display program-
ming.
Expansion Factor
Equations
EQ1.
Spec.Grav. = Density of Fluid / Density of Water
Given the reference temperature, reference specific gravity, a second temp. and a second
Spec.Grav., the Expansion Factor (C Factor) can be computed as follows:
EQ2. Used for Liquid Mass and Corrected Volume Equations
C = 1 -
√
(Spec.Grav.2 / Ref.Spec.Grav.) x 1,000,000
Temp.2 - Ref.Temp
Given the reference temperature, reference density, a second temp. and a second density,
the Expansion Factor (C Factor) can be computed as follows:
Example: Diesel fuel (0.845@20˚C, 0.830@42˚)
C = 1 -
√
0.83/0.845 x 1,000,000 = 405.25
(42-20)
EQ3. Used for Liquid Mass and Corrected Volume Equations
C = 1 -
√
(Dens.2 / Ref.Dens.) x 1,000,000
Temp.2 - Ref.Temp