Level measurement gets difficult fast when the media is aggressive, contaminated, viscous, or pasty. Fouling, chemical attack, and poor sensor placement can all lead to unstable readings and maintenance headaches. A screw-in level transmitter tackles many of these issues by measuring hydrostatic pressure directly from a robust installation point, and the LMK 351 Screw-in Level Transmitter is purpose-built for exactly these kinds of environments.
Positioned within Stork Solutions’ range of Screw-in level transmitter options, the LMK 351 combines a flush-mounted capacitive ceramic sensor with process connection choices designed to cope with challenging media.
1) A practical measurement principle for difficult liquids: hydrostatic level via screw-in installation
Screw-in level transmitters are often chosen when you do not want a submersible probe and would prefer a robust threaded installation into the bottom or side of a tank or pipework. This approach measures the hydrostatic pressure created by the liquid above the sensor, which can then be converted into a level reading.
We summarise the principle clearly on our Screw-in level transmitter page, including a useful rule of thumb: approximately 1 mWG is around 100 mbar. For operators and engineers, this straightforward relationship can simplify specification, commissioning, and troubleshooting.
2) Better performance in viscous and pasty media: flush-mounted diaphragm helps prevent clogging
Where paste-like or polluted media is involved, sensor faces can become a trap for build-up, leading to drift and slow response. The LMK 351 is designed with a flush-mounted diaphragm, which is specifically beneficial for viscous and pasty media because it helps reduce the likelihood of clogging and makes cleaning simpler.
This is one of the core reasons it is a strong fit for level measurement in applications involving thick or sticky fluids.
3) Materials and process connections that match aggressive environments
Aggressive media is not just about measurement accuracy, it is about whether the sensor survives. The LMK 351 offers process connection options aimed at the media challenge:
- A PVDF pressure port option for aggressive media
- A G 1 1/2″ pressure port version for pasty and polluted media
- A 99.9% Al2O3 (alumina) diaphragm option
This flexibility allows you to align the wetted materials with the chemical and mechanical demands of the process, rather than forcing a one-size-fits-all configuration.
4) High precision from a capacitive ceramic sensor element
The LMK 351 uses a capacitive ceramic sensor, which is highlighted as a key reason for its accuracy and reliability. In level measurement, especially at lower ranges, sensor stability and repeatability are just as important as headline accuracy. Ceramic sensing elements are commonly selected for tough duties where long-term performance is required.
5) Output options that suit both simple loops and integrated control systems
The LMK 351 supports common industrial output configurations:
- 2-wire 4–20 mA
- 3-wire 0–20 mA or 0–10 V (with other options on request)
This makes it easier to match the transmitter to existing plant infrastructure, whether you are working with classic current loops or interfacing into a PLC or data acquisition system.
6) Wide pressure range means one platform can cover many level applications
With nominal pressure ranges from 0–40 mbar up to 0–20 bar, the LMK 351 can serve a wide variety of tank heights and process pressures. That range supports standardisation across sites, where similar measurement technology is preferred even as vessel sizes vary.
7) Safety and compliance readiness: intrinsically safe (Ex ia) option
For hazardous areas where gases or dust are present, the LMK 351 is available in an intrinsically safe version (Ex ia). If you are designing or upgrading systems in regulated environments, being able to select an IS variant without changing the core measurement approach can simplify engineering and reduce project risk.
8) Application fit: from plant engineering to environmental and oil and fuel duties
Stork Solutions positions the LMK 351 for a broad range of practical applications, including:
- Plant and machine engineering
- Environmental engineering (water, sewage, recycling)
- Fuel and oil
- Viscous and pasty media duties (where flush mounting matters)
If your use case sits within these categories and the media is aggressive or hard to measure reliably, the LMK 351 is designed to address the typical failure points that cause level sensors to underperform.
Bottom line
A screw-in level transmitter improves level measurement in aggressive and pasty media by combining a robust installation method with a sensing face and materials designed to resist fouling and chemical attack. The LMK 351 Screw-in Level Transmitter brings that together with a flush-mounted capacitive ceramic sensor, PVDF and alternative process connection options, and the choice of 4–20
