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4.2 Corrections for Temperature Changes
The vibrating wire sensor itself is insensitive to temperature changes within the normal
operating range. The system, however, is not entirely unaffected by changes in water
temperature which influence the density and therefore, the buoyancy of the fluid. The
influence is relatively minor and can be accounted for to some degree by measuring
the water temperature and making density corrections. Alternatively, two sensors can
be used, one of which is completely submerged at all times and whose output can be
used to make corrections for the other sensor. This technique is not fool proof either
since the water may have temperature gradients which the submerged sensor may or
may not intersect. A temperature/density curve for water is shown in Figure 1. As can
be seen from the data the density of the water changes very little in the normal
operating range of the sensor. The following equation is used to correct for
temperature/density changes:
∆
H = (R0 ) G /(1- 0.0002T0 ) - (R1) G /(1- 0.0002T1)
Where T is the water temperature in
°
C.
