Level measurement on lubricant storage and process tanks

Application Note | Oil & Gas

  • Horizontal and vertical tanks of various dimensions and shapes
  • Level monitoring for improved process and stock inventory management
  • Automated data transmission to a control room


Mineral lube oils, refined from naturally occurring petroleum or crude oil, are used to reduce friction between moving surfaces. One of their largest applications, in the form of motor oil, is the protection of internal combustion engines of motor vehicles and powered equipment.


A lubricant producer processes and stocks lubricant oil in storage and process tanks of various shapes and dimensions. The horizontal or vertical, cylindrical tanks vary in height (1 to 20 m) and width (2 to 6 m). Each lubricant type needs a separate container and for each newly developed lubricant a tank is built, which adds 10-15 tanks to this production site every year. Lubricant oil is a low reflective and fairly expensive product: the customer needs a technology to accurately and reliably track the exact content of each tank for optimised process and stock inventory. In addition, some of the tanks call for contactless measurement due to the presence of agitators. Given the large number of tanks involved, the need for automated data transmission to a control room goes without saying. The sight glasses used earlier to indicate the oil level of each tank did not meet the above requirements in terms of accuracy and automated data transmission.

KROHNE oplossing

KROHNE has gradually replaced the sight glasses by 60 OPTIFLEX 1300 C TDR guided radar level transmitters with G1 process connection and single cable Ø 4 mm probes for the bigger tanks or single rod probes for the smaller tanks. They continuously measure the level right to the bottom of the storage tanks and transmit the data to the control room.

20 OPTIWAVE 7300 C FMCW radar level transmitters with DN 80 (3”) flange and antenna are installed on the process tanks and measure the level of the agitated oil surface. 80 OPTISWITCH 5100 C vibrating switches with G1 process connections were added on each tank as additional security to avoid tank overfilling.

Voordelen voor de klant

Both technologies, TDR and FMCW radar, are unaffected by physical property variations like changing density, viscosity or conductivity. Due to their high signal dynamics they are able to measure low refl ective medium with great accuracy. The OPTIFLEX TDR guided radar devices measure down to the tank bottom enabling the company to track the exact quantity of lubricant left in each vessel. The OPTIWAVE FMCW radar level transmitters, unaffected by internal, moving objects (agitators), measure continuously and with great reliability the level in the process tanks even during the fi lling process. Commissioning of OPTIFLEX 1300 C and OPTIWAVE 7300 C is reduced to a Quick Setup operation making installation straightforward. Added to the automated data transmission, these measuring devices help saving time and money. The OPTISWITCH 5000 C is a second security to prevent from overfi lling the tanks. These devices do not require commissioning as they are simple plug and play switches. Due to the wide product range offered by KROHNE the customer can stick to one supplier which reduces the cost from purchase to service.

Toegepaste instrumentatie


Guided radar (TDR) level transmitter for heavy-duty level and interface applications

  • Continuous measurement of level, distance, volume, mass or liquid-liquid interface
  • Measuring range: 0.2…35 m / 0.7…115 ft (liquids), 0.2…35 m / 0.7…115 ft (solids)
  • -50…+300°C / -58…+572°F; -1…300 barg / -14.5…4350 psig


Vibration level switch for process applications

  • Point level detection of liquids
  • Large choice of process fittings, housings and electronics
  • Density: ≥0.5 g/cm3 / 0.018 lb/in3
  • -50…+250°C / -58…+482°F; -1…64 barg / -14.5…928 psig


Radar (FMCW) level transmitter for liquids in agitated process applications

  • Continuous, non-contact measurement of level, distance, volume, mass and reflection
  • 24 GHz radar, Horn or Drop antennas
  • 0.2…80 m / 0.7…260 ft
  • -50…+200°C / -58…+392°F; -1…100 barg / -14.5…1450 psig