A public authority responsible for a harbour swimming facility was experiencing repeated failures of their underwater temperature sensors. The constant immersion in a saltwater environment led to rapid corrosion and data loss, requiring frequent and costly replacements. They needed a robust, long-term solution that could provide reliable and continuous temperature readings to their remote monitoring system.
- Application: Continuous water temperature monitoring in a saltwater harbour.
- Challenge: Repeated sensor failure due to corrosion from permanent seawater immersion.
- Solution: A fully submersible temperature probe featuring a marine bronze housing and a specialized TPE-U cable.
A public authority managing a coastal swimming facility faced a persistent challenge with their environmental monitoring equipment. The organization was responsible for providing continuous water temperature data for a saltwater harbour swimming area, but they experienced a recurring cycle of equipment failure. The sensors they deployed to measure the water temperature would invariably fail after a short period due to the harsh, corrosive nature of the saltwater. Having lost several units, they sought a genuinely robust and long-lasting temperature measurement solution that could end the costly cycle of frequent replacements.
The core requirement was for a temperature probe that could withstand permanent immersion in a saline environment without succumbing to corrosion. The desired measurement range was between -1°C and 30°C, typical for coastal ocean temperatures in their region. A secondary consideration was the data interface; the sensor needed to connect to a LoRaWAN transmitter for remote data acquisition, making a standard industrial signal output ideal. The physical installation required a cable length of at least two metres to position the data transmitter conveniently. While the customer had initially considered factors like UV resistance, their primary focus became material survivability, as previous probes had never lasted long enough for other environmental factors to become the point of failure.
The proposed solution was the STT-26 series submersible temperature probe, configured specifically to address the challenges of permanent saltwater immersion. The key feature of the selected instrument was its CA104 marine bronze housing. Unlike standard stainless steel, which can be susceptible to pitting and crevice corrosion in high-chloride environments like seawater, marine bronze is an alloy specifically designed to resist the corrosive effects of salt and prevent biofouling, making it the ideal material for this application. To ensure the integrity of the entire assembly, the probe was specified with a TPE-U (thermoplastic polyurethane elastomer) cable. This cable material is engineered for durability and chemical resistance, making it suitable for permanent submersion in seawater without degrading over time. This combination of a marine bronze body and a specialized submersible cable provides a complete package designed for long-term reliability.
The sensor provides a stable, 2-wire, 4-20mA analogue output, which is a robust industry standard, easily integrated with the customer’s intended LoRaWAN transmitter. The unit was supplied with a calibrated temperature range of -10 to +60°C, comfortably encompassing the required measurement window. An important accessory is the ability to rescale this range using an optional USB configuration kit. This allows an operator to narrow the sensor’s output span to their precise temperature range of interest, thereby maximizing the resolution of the data being transmitted. With an IP68 rating and a construction tested for submersion up to 50 metres, the transmitter is perfectly suited for long-term deployment in a harbour environment.
STT-26 Submersible Saltwater Temperature Probe
- Part No: STT-26-MT-005-C-00
- Sensor Type: PT100, Class A, 3 wire
- Output: 4 – 20mA / 2-wire
- Temperature Range: -10 to +60°C
- Probe Diameter: 25mm
- Probe Length: 80mm
- Housing Material: CA104 Marine Bronze
- Electrical Connection: 5m TPE-U cable
- Special Options: None
- Approvals: None
- IP Rating: 68, fully submersible to 100m depth
- Accessories: USB configuration kit