A project manager for a yacht services company was tasked with upgrading the fuel tank level monitoring systems on a large sailing vessel. The existing float-type sensors were providing unreliable and inaccurate readings, a critical issue for fuel management and voyage planning. The goal was to replace these legacy sensors with modern transducers to obtain true, continuous level readings across all three of the vessel’s diesel tanks. A key challenge was the nature of the tanks themselves, which were shallow and offered only limited access for installation.
- Application: Continuous diesel fuel tank level measurement.
- Place of Installation: A large sailing vessel.
- Challenge: To replace inaccurate and unreliable float-type sensors to gain “true readings” in shallow, limited-access tanks.
- Key Requirement: A robust, submersible sensor with high material compatibility for diesel fuel and flexible installation options.
To ensure accurate fuel gauging on a large sailing vessel, a reliable and robust level sensing solution was required to replace an outdated system of float switches. The existing mechanical floats were proving inadequate, leading to imprecise fuel inventory data which is unsuitable for a vessel undertaking long passages. The primary requirement was for a hydrostatic level sensor capable of measuring a relatively shallow depth of 1,200 mm of diesel fuel. The sensor needed to provide a continuous 4-20mA output signal for integration into the vessel’s monitoring system.
The installation environment presented several technical constraints. The diesel tanks were shallow with restricted access, making the installation process complex. The project manager required a solution that was adaptable, proposing that a sensor could either be lowered into the tank and secured to a pipe or, alternatively, fitted to a new 1” or 1-1/4” BSP threaded socket that could be welded onto the tank. This highlighted the need for a product with versatile mounting capabilities. Crucially, all wetted parts of the sensor had to be fully compatible with diesel fuel to ensure a long service life and prevent sensor failure or fuel contamination.
The proposed solution was the 18.605 G series submersible pressure transmitter. This sensor was identified as an ideal fit due to its unique combination of features that directly addressed the specific challenges of the application. Its primary advantage is its dual-purpose design. The sensor is fully submersible with an IP68 ingress protection rating and an oil-resistant PVC cable, allowing it to be lowered directly into the tank as the customer initially suggested. Simultaneously, it features an integrated G1/4″ male threaded process connection, providing the option for a secure, fixed mounting to the bottom of the tank.
Material compatibility, a critical factor for any fuel-related application, was assured by the 18.605 G series’s construction. The sensor features a stainless steel 1.4435 (316L) diaphragm and FKM (Viton) internal seals, both of which offer excellent long-term resistance to diesel fuel. The piezoresistive sensing technology provides a significant accuracy improvement over the previous float switches, meeting the customer’s core requirement for “true readings” with a standard accuracy of 0.5% full scale. Furthermore, its robust design is rated for high levels of vibration (10 g) and shock (100 g), making it perfectly suited for the demanding marine environment of a sailing yacht.
18.605 G Submersible Diesel Fuel 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