Calculation Inch:

Tank span = (Lmax x SG)

Tank Span: 108in X 0.75 = 81inH2O

4mA = Lmin x SG + (Hd x Sg) + (Ld x Sg)

= (0 x 0.75) + (60 in. x 0.934) + (180 in. x 0.934) = -112.08 inH2O

20mA = Lmax x SG + (Hd X 0.934) + (Ld X 0.934)

= (108 in. x 0.75) + (-112.08) = -31.08 inH2O

SPAN = 81 inH2O (-112.08 to -31.08 inH2O)

Note: Pressure (Ld) is applied to Low sensor side and will register as a negative digital pressure. Pressure (Hd) is pulling down on the high sensor side therefore would also register as a negative digital pressure therefore these values are additive.

Abbreviations:

Lmin = the minimum level of process and typically the 4mA lower range value

Lmax = the maximum level of process and typically the 20mA upper range value

Atm = Atmospheric pressure (vented tank)

SG = Specific gravity of the process

Sg = Specific gravity of the remote fill fluid

Hd = Capillary vertical distance from process to high side sensor

Ld= Capillary vertical distance going to low side sensor

Transmitter installed above Hd tapping point