(a) Describe, with the aid of a sketch, how a Bourdon Tube can be utilised to measure temperature.(8)
(b) State a typical application and location for this type of device.(2)
Bourdon Tube: A Pressure Measurement Device
A Bourdon tube is a hollow, curved metal tube used to measure pressure. It’s a common component in pressure gauges.
1. History of the Bourdon Tube and Schaffer Diaphragm Pressure Gauges
How it Works:
- Tube Shape: The tube is typically oval in cross-section and curved into a C or helical shape. 1. Bourdon tube pressure gauge – WIKA www.wika.com
- Pressure Application: When pressure is applied to the inside of the tube, it tends to straighten out due to the oval shape. 1. Bourdon gauge – Oxford Reference www.oxfordreference.com
- Movement: The movement of the tube’s free end is proportional to the applied pressure. 1. Bourdon tube pressure gauge – WIKA www.wika.com
- Mechanical Linkage: This movement is typically connected to a gear mechanism that drives a pointer on a dial, indicating the pressure. 1. Bourdon Tube Pressure Gauge – How It Works | Tameson.com tameson.com
Key Points:
Relatively inexpensive compared to other pressure measurement technologies.
Simple and reliable design.
Suitable for measuring a wide range of pressures. 1. Bourdon Tube Pressure Gauge – How It Works | Tameson.com tameson.com
Can be used for both liquid and gas pressures. 1. Bourdon tube pressure gauge – WIKA www.wika.com
Using a Bourdon Tube for Temperature Measurement
While Bourdon tubes are primarily used for pressure measurement, they can indirectly be used for temperature measurement through a coupled device.
Principle:
- Pressure-Temperature Relationship: Certain systems, like those involving gases, have a direct relationship between pressure and temperature. For example, in a closed container, increasing the temperature will increase the pressure of a gas.
- Bourdon Tube as Pressure Sensor: A Bourdon tube can measure this increased pressure caused by the temperature rise.
- Calibration: By calibrating the Bourdon tube to the specific gas and container, the pressure reading can be converted into a temperature reading.
Limitations:
- Indirect Measurement: This method relies on the accurate relationship between pressure and temperature for the specific gas and system.
- Accuracy: The accuracy of the temperature measurement depends on the accuracy of the pressure measurement and the precision of the calibration.
- Response Time: The response time of the system can be slower compared to dedicated temperature sensors.
While it is possible to use a Bourdon tube for temperature measurement in this indirect manner, it’s generally not as accurate or efficient as using dedicated temperature sensors like thermocouples or RTDs.
Bourdon Tubes on Superyachts
Bourdon tubes are commonly found on superyachts for monitoring various pressures within the vessel’s systems. Here are some typical applications:
- Engine Room:
- Measuring water pressure in the cooling system
- Monitoring oil pressure in engines and hydraulic systems
- Indicating fuel pump discharge pressure
- Measuring air compressor discharge pressure
- Hull and Systems:
- Monitoring bilge pump pressure
- Indicating water pressure for showers, sinks, and other water systems
- Measuring hydraulic system pressures for stabilizers, winches, and other equipment
- Monitoring fire suppression system pressure
- Other Applications:
- Pressure gauges for air conditioning systems
- Pressure indicators for pneumatic systems
While modern electronic pressure sensors are becoming increasingly common, Bourdon tube gauges still offer a reliable and often more affordable option for many applications on superyachts.
A typical use of a Bourdon tube on a superyacht is in the engine room.
One of the most common applications is for monitoring engine oil pressure. The Bourdon tube gauge connected to the engine’s oil system provides a visual indication of the oil pressure, crucial for ensuring the engine’s health and preventing damage.
Other common uses include:
- Monitoring water pressure in the cooling system
- Indicating fuel pump discharge pressure
- Measuring air compressor discharge pressure
By providing real-time pressure readings, Bourdon tube gauges help in maintaining optimal engine performance and preventing potential issues.
Another Typical Use of a Bourdon Tube on Superyachts
Monitoring water pressure is another common application of Bourdon tubes on superyachts.
- Freshwater Systems: Bourdon tube gauges are used to indicate water pressure in the vessel’s freshwater system, including sinks, showers, and galley equipment.
- Seawater Systems: These gauges can monitor the pressure in seawater systems, such as those used for cooling engines or operating hydraulic systems.
By providing real-time water pressure readings, Bourdon tube gauges help ensure proper system operation and identify potential issues.
Typical Location of Bourdon Tube Sensors on Superyachts
Engine Room
- Engine oil pressure: Located at the engine block or oil pump outlet.
- Cooling water pressure: Mounted on the water pump discharge or cooling system manifold.
- Fuel pump discharge pressure: Installed at the fuel pump outlet.
- Turbocharger boost pressure: Located at the turbocharger outlet.
Hull and Systems
- Bilge pump pressure: Positioned at the bilge pump outlet.
- Freshwater system pressure: Installed at the water pump discharge or near the main water distribution manifold.
- Seawater system pressure: Located at the seawater pump outlet or on the intake side of seawater systems.
- Hydraulic system pressure: Mounted on the hydraulic pump outlet or at critical points in the system.
By strategically placing Bourdon tube gauges in these locations, yacht operators can effectively monitor various pressure points, ensuring optimal system performance and preventing potential issues.