BMW operates one of the advanced car building plants that incorporates perfect manufacturing practices. In the final production step, the new sedans are filled with brake fluid, hydraulic oil for the power steering, frigen for the air conditioning, gear oil and fuel.
In order to ensure the continuous supply of fuels and oils at all times, a filling station with underground tanks was built on the factory premises.
Sophisticated measurement technology controls the filling levels of the tanks and sends the current levels directly to the control system. Suppliers of the fuels and oils are informed automatically at the appropriate times when stocks are falling and when replacements will be necessary.
Each supplier is then responsible for making sure that their tank is refilled. The successful implementation of this Vendor Managed Inventory (VMI) concept is based on Endress + Hauser ’s measurement technology and Profibus PA.
For the continuous level measurements of fuels and oils in the tanks, the Micropilot M FMR240 was selected.
This non-contact, microwave based instrument is ideal for level measurement in Ex areas in small vessels since it is fitted with a small antenna, and has an accuracy of ±3mm.
To protect the filling pumps from running dry and serve as an overfilling safeguard for the tanks, the Endress + Hauser Liquiphant FTL50s were installed.
This robust maintenance free, detection switches operate reliably irrespective of the properties (conductivity, viscosity, density etc) of the liquids using the vibrating fork principle, and are NAMUR approved.
To measure the gauge pressure at the supply pumps, the Cerabar M pressure transmitter range was chosen. The measured values and recorder alerts are transmitted to the fuel and oil suppliers via the Endress + Hauser Fieldgate FXA 520.
Profibus PA is specifically approved for use in hazardous (Ex) zones and connects all the instruments via a 2-wire bus. Endress + Hauser advised BMW on the choice of measurement technology as well as implementing a Profibus strategy.
They supplied all the necessary peripheral equipment such as segment couplers (to convert Profibus DP to PA), T-boxes, bus terminators, and cabling, as well as the freely programmable controller which serves as a Profibus master class I host, and implemented all system commissioning and programming.
Following BMW’s implementation of reliable measurement technology and VMI, the timely and accurate availability of oils and fuels is ensured and their cars roll off the assembly line without delays.