Continuous level measurement is a critical requirement in wastewater treatment, sewage systems, recycling processes, dumpsites and aggressive chemical media. In these applications, the measuring instrument must withstand contamination, chemical exposure and demanding operating conditions while still delivering stable and accurate level data.
The BD|SENSORS LMK 807 is a plastic submersible probe designed specifically for continuous level measurement in highly polluted and aggressive media. With its compact 35 mm diameter, ceramic sensor technology, IP68 protection and strong media compatibility, LMK 807 offers a practical solution for harsh level measurement applications.
What Is LMK 807?
LMK 807 is a plastic submersible level probe used for hydrostatic level measurement. It is designed to be immersed directly into the medium and to measure the liquid level according to the pressure generated by the liquid column above the sensor.
The probe is especially suitable for applications where the medium is polluted, chemically aggressive or difficult for standard metallic sensors. Its plastic housing and ceramic diaphragm help provide reliable operation in challenging environments.
Designed for Aggressive Media
One of the main advantages of LMK 807 is its suitability for aggressive liquids. The device can be used for level measurement in many acids and lyes, depending on material compatibility.
The media-wetted housing is made of PP-HT, while the diaphragm is made of Al₂O₃ 96% ceramic. Seal material options include FKM, EPDM and FFKM, allowing the probe to be adapted to different chemical environments.
Different cable materials are also available, including PVC, PUR and FEP, helping users select the most suitable configuration for the process medium.
Ideal for Sewage and Wastewater Applications
LMK 807 is also designed for sewage and wastewater environments. Typical applications include wastewater treatment plants, water recycling systems and dumpsite applications.
In these processes, the medium may contain solid particles, deposits or contamination. The flush-mounted ceramic sensor helps simplify cleaning when solids from the medium accumulate on the sensor surface. This design supports easier maintenance and more reliable long-term operation.
Hydrostatic Level Measurement Principle
The LMK 807 works according to the hydrostatic pressure principle. As the liquid level rises, the pressure acting on the submerged sensor increases. The probe converts this pressure into an electrical signal proportional to the liquid level.
This measurement method is widely used in tanks, basins, wells and open vessels because it provides continuous level data with simple installation. The LMK 807 transmits this information via a 4–20 mA two-wire output, which can be connected to control systems, indicators, PLCs or monitoring devices.
Measurement Ranges
The LMK 807 covers nominal pressure ranges from 0–4 mH₂O up to 0–100 mH₂O. Equivalent pressure ranges include 0.4 bar to 10 bar.
This allows the probe to be used in different tank depths and level measurement applications. Available level ranges include 4, 6, 10, 16, 25, 40, 60 and 100 mH₂O.
The maximum ambient pressure at the housing is 20 bar, supporting reliable operation in submerged environments within the specified limits.
Accuracy and Long-Term Stability
The LMK 807 offers an accuracy of ≤ ±0.5% FSO according to IEC 61298-2. Long-term stability is specified as ≤ ±0.1% FSO per year at reference conditions.
This stable measurement performance makes LMK 807 suitable for applications where continuous and dependable level data is required over long operating periods.
The response time is ≤10 ms, enabling fast signal response for monitoring and automation systems.
Temperature and Environmental Conditions
The permissible temperature range for medium, electronics, environment and storage is 0 °C to +60 °C. The probe has IP68 ingress protection, making it suitable for permanent submersible use.
Electrical protection features include permanent short-circuit protection and reverse polarity protection. Electromagnetic compatibility is specified according to EN 61326.
For additional protection, an external overvoltage protection unit in terminal boxes KL 1 or KL 2 with atmospheric pressure reference is available on request.
Cable and Electrical Connection Options
LMK 807 uses a shielded cable with integrated ventilation tube for atmospheric pressure reference. Cable sheath options include PVC, PUR and FEP, each with different temperature and chemical resistance characteristics.
The standard cable diameter is 7.4 mm. Cable capacitance is specified as 160 pF/m, and cable inductance is 1 µH/m. The static bending radius is ten times the cable diameter, while dynamic applications require twenty times the cable diameter.
The electrical connection follows a two-wire current system. According to the cable color configuration, supply positive is white, supply negative is brown and shield is green-yellow.
SIL 2 Option for Safety-Related Applications
LMK 807 is available with an optional SIL 2 version according to IEC 61508 / IEC 61511. This makes it suitable for safety-related level monitoring applications where functional safety requirements must be considered.
For plants that require documented safety performance in monitoring or control loops, the SIL 2 option provides additional configuration flexibility.
Compact and Easy to Handle
The probe has a diameter of 35 mm and weighs approximately 200 g without cable. Its compact form supports easy handling, installation and maintenance.
The removable protection cap shown in the datasheet helps protect the sensor area while still allowing access when cleaning is required. This is particularly useful in applications where medium deposits may accumulate on the sensor.
Terminal Clamp Accessory
A terminal clamp accessory is available for probe installation. It is suitable for probes with cable diameters from 5.5 mm to 10.5 mm.
The terminal clamp housing is available in zinc-plated steel as standard or optional stainless steel 1.4301 / 304. The clamping jaws and positioning clips are made of fibre-glass reinforced PA. This accessory supports practical installation and secure cable positioning in field applications.
Why Choose LMK 807?
LMK 807 is a strong choice for level measurement applications where aggressive or polluted media make conventional sensor materials unsuitable.
Its ceramic diaphragm, plastic housing, selectable elastomers, multiple cable options, flush-mounted sensor design and IP68 protection provide a robust configuration for wastewater and chemical applications.
The 4–20 mA output makes integration into industrial automation systems simple and reliable, while the optional SIL 2 version supports safety-related applications.
Conclusion
The BD|SENSORS LMK 807 Plastic Submersible Probe is a reliable solution for continuous level measurement in aggressive and highly polluted media. With its PP-HT housing, ceramic Al₂O₃ diaphragm, selectable seal and cable materials, IP68 protection and 4–20 mA output, it is well suited for sewage, wastewater treatment, water recycling, dumpsites and chemical level measurement applications.
For facilities that need a compact, easy-to-handle and chemically compatible submersible probe, LMK 807 provides stable and practical level measurement performance in demanding environments.