AME Unit 9 Q8

Thermocouple-Based System

A common method for measuring and remotely indicating temperature on superyachts involves the use of thermocouples.

How it works:

1. Thermocouple Placement: Thermocouples are strategically placed in various locations throughout the yacht, such as engine compartments, cargo holds, refrigeration units, and living areas.
2. Signal Conditioning: The low-voltage output from the thermocouples is amplified and conditioned to match the input requirements of the data acquisition system.
3. Data Acquisition: A data acquisition unit (DAU) collects temperature data from multiple thermocouples.
4. Data Transmission: The DAU transmits the temperature data to a central control or monitoring station using wired or wireless communication protocols.
5. Display and Control: The temperature data is displayed on a central control panel or remote monitoring system.

Key components:

• Thermocouples
• Signal conditioning electronics
• Data acquisition unit
• Communication system
• Display or control interface

Advantages:

• Wide temperature range
• Relatively inexpensive
• Robust and reliable

Disadvantages:

• Low-level output signal requiring amplification
• Potential for noise and interference

By using thermocouples and a suitable data acquisition system, superyacht operators can effectively monitor critical temperatures throughout the vessel.

While thermocouples are widely used, other temperature sensors offer advantages in specific applications.

Resistance Temperature Detectors (RTDs)

• Principle: Based on the change in electrical resistance of a metal, typically platinum, with temperature.   1. What is an RTD | Understanding RTD Sensors – TE Connectivity www.te.com
• Advantages: Higher accuracy, better stability, and wider temperature range compared to thermocouples.
• Applications: Precise temperature control, scientific research, and industrial processes.

Thermistors

• Principle: Based on the change in resistance of a semiconductor material with temperature.   1. Resistance thermometers and thermistors – IET Digital Library digital-library.theiet.org
• Advantages: High sensitivity, fast response time, and compact size.
• Applications: Temperature control, automotive sensors, medical equipment.

Infrared Thermometers

• Principle: Measures temperature by detecting infrared radiation emitted by an object.   1. A Comprehensive Guide to Infrared Thermometers – RS Components uk.rs-online.com
• Advantages: Non-contact measurement, fast response time, suitable for moving objects.
• Limitations: Accuracy can be affected by emissivity of the target surface.

Other Sensors

• Thermocouples: While mentioned earlier, other types of thermocouples (e.g., J, K, T, E, S, B, R) offer different temperature ranges and sensitivities.
• Bimetallic Thermometers: Simple and inexpensive but less accurate than electronic sensors.

The choice of temperature sensor depends on factors such as required accuracy, response time, temperature range, cost, and environmental conditions.

Flow rate measurement is crucial for various systems on a superyacht, including fuel, water, and waste systems. Here are common methods:

1. Differential Pressure Flow Meters

• Principle: Measures the pressure difference across a flow restriction (orifice plate, venturi tube) to determine flow rate.
• Advantages: Reliable, accurate, and widely used.
• Disadvantages: Can cause pressure loss in the system.

2. Electromagnetic Flow Meters

• Principle: Induces a voltage across a conductive fluid moving through a pipe. The induced voltage is proportional to the flow rate.
• Advantages: Accurate, no pressure loss, suitable for various fluids.
• Disadvantages: Requires conductive fluids.

3. Ultrasonic Flow Meters

• Principle: Measures the transit time of ultrasonic pulses traveling through a fluid.
• Advantages: Non-invasive, accurate, suitable for various fluids.
• Disadvantages: Can be affected by fluid properties and installation conditions.

4. Turbine Flow Meters

• Principle: A turbine rotates at a speed proportional to the flow rate.
• Advantages: Simple, reliable, and accurate for liquids.
• Disadvantages: Pressure loss and potential wear of the turbine.

5. Vortex Flow Meters

• Principle: Generates vortices behind a bluff body in the flow, which are measured electronically.
• Advantages: High accuracy, wide flow range, low pressure loss.
• Disadvantages: Can be sensitive to fluid conditions.

6. Coriolis Flow Meters

• Principle: Measures the Coriolis force exerted on a vibrating tube as fluid flows through it.
• Advantages: High accuracy, mass flow measurement, wide flow range.
• Disadvantages: Higher cost compared to other methods.

The choice of flow meter depends on factors such as:

Cost considerations

Fluid type (water, fuel, waste)

Flow rate range

Accuracy requirements

Pressure drop limitations

The placement of flow meters on a superyacht depends on the specific system being monitored and the desired level of control. Here are some common locations:

Engine Room

• Fuel flow meters: Installed in the main fuel lines to monitor fuel consumption and engine performance.
• Cooling water flow meters: Placed in the engine cooling water supply and return lines.
• Lubricating oil flow meters: Installed in the oil supply and return lines to monitor oil flow and pump performance.
• Hydraulic system flow meters: Located in the hydraulic system supply and return lines to monitor fluid flow.

Water Systems

• Freshwater flow meters: Installed on the water supply lines to monitor water consumption and prevent leaks.
• Seawater flow meters: Located in the seawater intake and discharge lines for various systems (e.g., cooling, sanitation).
• Wastewater flow meters: Installed on the wastewater discharge lines for monitoring and treatment purposes.

Other Systems

• Bilge pump flow meters: To monitor the amount of water pumped out.
• Firefighting system flow meters: To measure water flow during fire suppression.

It’s important to note that the specific location of flow meters can vary depending on the yacht’s design, equipment layout, and monitoring requirements.