28
Fluid Temperature Correction
For certain applications, it may be advantageous to normalize the refractive index output to stan-
dard temperature (60°F).
During the development of FuelCheck, a series of flow loop measurements was made at various
fluid temperatures. From the experimental data, the following conclusion can be made:
V
60
=
V+(0.01374(60-T))
In most instances, a signal conditioner is employed to convert the bipolar photoelectric voltage
into a standard voltage or current. In this case, the following scaling corrections can be made:
S
60
= (S(V
max
-V
min
)+(0.22(60-T)))/(V
max
-V
min
)
where:
V
FOI
output,
V
V
60
FOI output corrected to 60°F, V
S
60
signal conditioner output corrected to 60°F, mA
S
signal conditioner output, mA
V
max
photoelectric output at maximum signal conditioner output, V
V
min
photoelectric output at minimum signal conditioner output, V
T
fluid temperature, °F
As an example, let us assume that a signal conditioner is being used to convert the photoelectric
output voltage to a 4-20 mA current, and that it is calibrated so that a -1.03 to -4.22 photoelectric
voltage range is translated to a 4-20 mA signal. Presently, the signal conditioner output is 11.3
mA, and the fluid temperature is 104°F.
S 11.3
mA
V
max
-4.22
V
V
min
-1.03
V
T 104°F
S
60
=(11.3*(-4.22--1.03)+(0.22*(60-104)))/(-4.22--1.03)
S
60
= 14.3 mA
Chapter
6
Summary of Contents for FuelCheck
Page 1: ...F FU UE EL LC CH HE EC CK K...
Page 24: ...23 19 5 11 5 6 0 2 25 2 5 Figure 33 FuelCheck Controller mounting dimensions...
Page 34: ...33...
Page 35: ...34 APPENDICES...
