🔍 Key Concepts

• Location and purpose of the viscosimeter in a fuel oil system (see symbol "V" after the final heaters and filters). • How viscosity is commonly measured in flowing systems (think resistance to flow through a restriction or capillary). • Difference between measuring a single pressure and measuring a pressure differential across a device.

💭 Think About

• From the piping diagram, what is the viscosimeter actually connected across, and does that suggest it cares about one point in the line or two points? • If you needed an electrical signal that changed as viscosity changed, would it be more useful to sense only inlet pressure, only outlet pressure, or how much pressure is lost while the oil flows through the measuring element? • Which answer choice best matches the idea of measuring how hard it is for the fuel to flow through a restriction at a given flow rate?.

✅ Before You Answer

• Verify which side(s) of the viscosimeter the sensing lines attach to in the drawing—one side only or both inlet and outlet. • Confirm that a viscosity measuring device in automatic control must provide a signal that varies with a change in flow resistance, not just static pressure. • Eliminate any options that mention variables the viscosimeter is not physically connected to in the diagram (such as upstream heaters or unrelated temperatures).