An operator of a sustainable microgrid required a robust and certified solution for monitoring its potable water storage tanks. The key challenge was to find a single instrument capable of continuously and accurately measuring both the water level up to 40 feet and the water temperature. Crucially, any instrument submerged in the tanks had to possess the necessary certifications to ensure it was safe for use in drinking water.
- Simultaneous measurement of tank level and water temperature.
- Required a measurement range of 0 to 40 feet of water column (ftHâ‚‚O).
- Mandatory certification for use in potable water applications.
- Standard analogue outputs for integration into an existing control system.
Managing essential resources is a primary function for operators of self-sufficient microgrids, particularly when it comes to the storage and distribution of potable water. For one such facility located in the Bahamas, maintaining a clear and constant view of their water tank reserves was critical for operational continuity. The application demanded a reliable method for measuring water levels in tanks up to 40 feet deep. In addition to volume monitoring, tracking the water temperature was also a requirement to monitor water quality and environmental conditions within the tanks.
A significant challenge in this application was the nature of the media itself, which was drinking water. Any instrumentation destined for long-term submersion must be constructed from materials that will not contaminate the water. This necessitates specific certifications that guarantee the materials are safe for human consumption. The solution, therefore, needed to go beyond standard industrial sensor specifications and meet stringent international standards for potable water contact.
The proposed solution was the LMP307T series submersible level and temperature sensor. This instrument is specifically engineered for dual-parameter measurement in applications like drinking water systems. It neatly addresses the core requirements by incorporating both a pressure sensor for level detection and a temperature sensor within a single, submersible 316L stainless steel housing.
A key advantage of this solution is its certified construction. The sensor is available with a drinking water certificate according to DVGW W 270 and UBA KTW standards. This certification is achieved through the use of specific wetted materials, including EPDM seals and a special TPE-U cable sheath, ensuring no harmful substances can leach into the water supply. For a potable water application, this feature is non-negotiable and provides the necessary assurance of safety and compliance.
The sensor provides two separate and independent 4-20mA analogue output signals, one for level and one for temperature, from a single device. This 2-in-1 design reduces complexity and cost by minimizing wiring and requiring only one installation point per tank. For accurate hydrostatic level measurement in a vented tank, the sensor’s cable includes an integrated ventilation tube. This feature ensures that the sensor is always referenced to the local atmospheric pressure, automatically compensating for barometric pressure fluctuations and preventing them from causing errors in the level reading. This results in a true and reliable measurement of the water column height, which is essential for accurate inventory management.
LMP307T DVGW/KTW Certified Submersible Level and Temperature Sensor
- Sensor Type: Level and Temperature
- Level Sensing Range: 0-40 ftH2O
- Reference Type: Gauge / Vented (atm to +P)
- Temperature Sensing Range: 0-30C / 32-86F
- Output Signal: 4-20mA, 2 wire
- Accuracy: 0.35%FS above, 0.5% FS below 4mH2O (11-12bit res)
- Installation Type: Submersible probe with flush diaphragm and detachable nose cone
- Housing Material: Stainless Steel 316L
- Diaphragm Material: Stainless Steel 316L
- Media Exposed Seals: DVGW/KTW EPDM
- Cable Type: DVGW/KTW TPE-U (70degC max)
- Cable Length: 50
- Cable Length Units: Feet (ft)
- Optional Extras: Drinking water certificate (DVGW W 270 / UBA KTW)