Process engineers are compelled to pursue more precise and reliable level measurement systems, driven by the demands of advanced automated processing systems, the necessity for increasingly rigorous process control, and a regulatory landscape that grows ever more stringent. Enhanced accuracy in level measurement enables the reduction of variability in chemical processes, which in turn leads to improved product quality, lower costs, and minimized waste. Regulatory standards—particularly those overseeing electronic records—impose strict mandates on accuracy, reliability, and electronic reporting capabilities. The latest level measurement technologies are well-suited to fulfill these requirements.
Undoubtedly, the simplest and oldest industrial device for liquid level monitoring is the sight glass. As a manual measurement method, sight glasses have long been plagued by several limitations. The transparent material they employ is susceptible to catastrophic failure, which can result in environmental damage, hazardous situations for workers, and even fires or explosions. Their seals are prone to leaking, and any buildup present can obscure the visible level. It can be said without hesitation that conventional sight glasses represent the weakest component in any installation. Consequently, they are being quickly replaced by more advanced technologies.
Other level-detection devices include those that rely on specific gravity—the physical property most frequently used to detect the level surface. A basic float with a specific gravity between that of the process fluid and the vapor in the headspace will float on the surface, precisely tracking its rises and falls. Hydrostatic head measurements have also been widely utilized to deduce level.
Arguably, the most notable distinction between earlier continuous liquid-level measurement technologies and the ones now growing in popularity lies in the adoption of time-of-flight (TOF) measurements to convert liquid level into a standard output signal. These devices generally function by calculating the distance between the liquid level and a reference point located at a sensor or transmitter near the top of the vessel. Typically, the system emits a pulse wave from this reference point; this wave travels through either the vapor space above the liquid or a conductive medium, reflects off the liquid’s surface, and then returns to a receiver at the reference point. An electronic timing circuit records the total duration of this round trip. By dividing the total travel time by twice the speed of the wave, the distance to the fluid’s surface is determined. The primary difference between these technologies lies in the type of pulse used for the measurement. Ultrasound, microwaves (radar), and light have all demonstrated their effectiveness in this application.
Guided wave radar level transmitters
LWT310 LWT320 MT5000
For high-accuracy, reliable measurements even in harsh conditions.
Using radar frequencies, guided in a probe going into the monitored vessel, guided-wave radar level measurement provides continuous, reliable measurements with high accuracy. The radar wave being guided by the probe, the wave energy remains high which allows measurement even in harsh conditions.
The new LWT series of guided-wave radar builds on the legacy of the MT5000 series. Now with more powerful LevelExpertTM algorithm to efficiently track the level through the clutter, you do not need to be a radar expert to use this device: The expert is now inside the device!
Customer benefits:
Microwaves are unaffected by temperature, pressure, specific gravity and vapors
Easy to install
No moving parts
Ignores light continuous coatings
Good for vacuum service
More direct energy return – more consistent signal
Built-in waveform screen (Scope Trace)
Industries served:
Oil and gas production
Refining
Pharmaceutical and biotech
Power generation
Pulp and paper
Iron and steel
Chemicals
Food and beverage
Marine
