Page 320 - Introduction to Marine Engineering

294 Instrumentation and control

Pressure tapping
led to differential
pressure gauge
/ \ Constant speed
gear pump

t /
•*- . / Gear pump
suction
Z
Outlet
Damping Measuring Oilflow
capillary capillary

(a) Inlet

Thermometer

(b)
Figure 15.20 Viscosity sensor, (a) diagrammatic; (b) actual

reduce its viscosity, and vice-versa. As a result of the varying properties
of marine fuels, often within one tank, actual viscosity must be
continuously measured and then corrected by temperature adjustment.
The sensing device is shown in Figure 15.20. A small constant speed
gear pump forces a fixed quantity of oil through a capillary (narrow