A manufacturer needed a level sensing solution for a miniature, high-temperature sewage tank where external measurement was not possible. The key was to find a submersible sensor that could withstand the harsh process conditions while providing accurate, continuous level data for the shallow 25 cm tank height. The LMK 382 series hydrostatic level transmitter, with its specialized features, provided an ideal solution.
- Application: Continuous level measurement in a small, 25 cm high, metallic sewage tank.
- Challenge: The process medium reaches 90°C, and the sensor must be fully submerged in the aggressive wastewater.
- Solution: An LMK 382 series submersible hydrostatic level transmitter with a ceramic diaphragm and a high-temperature TPE cable.
- Benefit: The sensor provides a precise 4-20mA output corresponding to the 0-40 cm level, with robust materials ensuring long-term reliability in the demanding high-temperature, corrosive environment.
A manufacturer of compact sanitation systems required a reliable method for monitoring the fluid level within a small sewage tank. The application presented several technical challenges. The tank, measuring only 25 cm in height, was constructed from thick metal, which precluded the use of any external, non-contact level sensing technologies. Therefore, a fully submersible sensor was necessary. The primary challenge was the process medium itself: wastewater at temperatures reaching up to 90°C. The sensor had to not only withstand these high temperatures but also resist the corrosive and potentially fouling nature of the sewage, all while providing a continuous and accurate output to determine if the tank was empty or full.
The proposed solution was the LMK 382 series submersible level transmitter. This sensor operates on the principle of hydrostatic pressure, where the probe is positioned at the bottom of the tank to measure the pressure exerted by the column of liquid directly above it. This pressure reading is then converted into a linear 4-20mA electrical signal corresponding to the liquid level. For this specific application, the sensor was calibrated to its lowest range of 0 to 40 cm of water column (cmH2O). This calibration ensures that a 4mA output corresponds to an empty tank and a 14mA output to a full tank, with a high degree of precision across the entire measurement span.
The LMK 382 series is particularly well-suited for this demanding environment due to its specialized design features. Its robust construction, featuring a 316L stainless steel housing and a capacitive ceramic diaphragm, is engineered specifically for use in sewage and other viscous, aggressive media. The ceramic sensing element is not only highly resistant to chemical attack but also to abrasion, ensuring long-term stability and reliability. Furthermore, the selection of a TPE cable provides the necessary high-temperature tolerance, with a maximum rating of 125°C, offering a significant safety margin above the application’s 90°C requirement. The low measurement range capability of the sensor is a key advantage, allowing for high-resolution monitoring of the very shallow 25 cm tank height, a task where many standard level sensors would lack the required precision.
LMK 382 Submersible Sewage Level Transmitter
- SKU ID: s1-lmk382-0004
- Part No: 566-0400-1-2-1-1-4-3-005-000
- Pressure Range: 0 to 40 cmH2O
- Reference Type: Gauge / Vented (atm to +P)
- Output Signal: 4-20mA, 2 wire
- Accuracy: 0.35% FS
- Installation Type: Probe version with flush diaphragm
- Housing Material: Stainless Steel 316L
- Diaphragm Material: Ceramic Al2O3 96%
- Media Exposed Seals: FKM
- Cable Type: TPE (125degC max)
- Cable Length: 5
- Cable Length Units: Metres (m)