Monitoring consumable and waste fluid levels on a classic 120ft long sailing yacht presents a unique set of challenges, especially when dealing with multiple tanks of non-uniform geometry. A robust and reliable instrumentation solution is required to provide the crew with accurate data for managing fuel, water, and waste during regattas and extended voyages. The hydrostatic measurement principle offers a straightforward and effective method for this application.
- Application: Continuous level monitoring in 8 separate water and fuel tanks on a classic yacht.
- Challenge: Angled and irregularly shaped tanks require level-to-volume conversion for accurate volume readings.
- Solution: 18.605 G series submersible level transmitters with a 4-20mA output.
- Benefit: Provides precise, real-time level data for input into a display or PLC capable of multipoint linearization, ensuring accurate management of all onboard fluids.
Maintaining and operating a classic 120 feet long sailing yacht, renowned for its participation in regattas and leisure charters, requires the seamless integration of modern technology to ensure reliability and safety. A key operational challenge on such a vessel is the accurate monitoring of various onboard liquids. The yacht is equipped with eight separate tanks for potable water, grey water, black water, and diesel fuel, all essential for extended sailing. The primary difficulty stemmed from the unique construction of the tanks; due to the yacht’s hull design, the tanks are not simple cubes but feature angled tops and bottoms. This irregular geometry means that the liquid level does not change linearly with the volume, posing a significant problem for accurate gauging.
The project required a level monitoring solution for all eight tanks, with heights ranging from 625 mm to 1200 mm. The system needed to be compatible with different liquid media, including fresh water (SG 1.0), waste water (SG 1.0), and diesel fuel (SG ~0.85). Furthermore, the output signal had to be a robust, industry-standard 4-20mA signal powered by a 24VDC supply, allowing for integration with the vessel’s central monitoring system. The core issue was not just measuring the level, but providing a basis for calculating the actual volume in litres within these non-uniform tanks, a critical piece of information for the crew when planning voyages.
The proposed solution was the 18.605 G series submersible hydrostatic level transmitter. These sensors are specifically designed for applications like this, offering a combination of features perfectly suited to the demanding marine environment and the specific technical requirements of the yacht. A sensor with a measurement range of 1.2 mH₂O was selected to accommodate the tallest tank, with other ranges tailored to the remaining tanks.
The 4-20mA output from the sensor provides a precise, continuous, and linear measurement of the liquid’s height (hydrostatic pressure). While this signal directly indicates the level, its key advantage in this application is serving as a high-quality input for a programmable display or control system. Such a system can be configured with a multi-point linearisation table or “strapping chart.” This allows the system to accurately convert the level reading from the sensor into a true volumetric reading (e.g., in litres). For example, the interface can be programmed to understand that a sensor output of 12mA (representing 50% of the maximum measurable height) in an angled tank might correspond to only 40% of the total volume, ensuring the crew has an accurate understanding of the resources available.
The construction of the 18.605 G series is ideal for this use case. The sensor’s housing is made from 304 stainless steel, while the sensing diaphragm, which is in direct contact with the liquid, is made from the more corrosion-resistant 316L stainless steel. Combined with FKM seals, these materials ensure compatibility with fresh water, waste water, and diesel fuel, guaranteeing a long operational life and preventing sensor failure due to corrosion.
For installation, the sensor’s IP68-rated submersible design means it can simply be lowered to the bottom of each tank. The integrated, specially designed cable contains a vent tube that runs its entire length. This vent ensures the sensor is always referenced to the local atmospheric pressure, so it only measures the pressure exerted by the column of liquid. This vented gauge design is critical in a marine environment as it negates the effect of barometric pressure fluctuations, ensuring the level readings remain accurate regardless of changing weather conditions.
18.605 G Submersible Diesel Fuel/Water Level Transmitter
- SKU ID: s1-18605g-0023
- Part No: 18.605G-1200-M-1-8-1-006-300-1-000
- Measuring Range: 1.2 mH2O (3.94 ftH2O)
- Reference Type: Gauge / Vented (atm to +P)
- Output Signal: 4-20mA, 2 wire
- Accuracy: 1% FSO
- Electrical Connection: IP68 submersible cable
- Cable Type: PVC (70degC max)
- Cable Length: 6 metres (19.69 feet)
- Housing Material: Stainless Steel 304
- Diaphragm Material: Stainless Steel 316L
- Media Exposed Seals: FKM
- Mechanical Connection: G1/4 male