Plumb bob system for the building materials industry
Fig. 1 The Nivobob 4000 is a plumb bob optimized... › It is not that easy to determine the fill level of a closed silo. Nevertheless, in many fields it is necessary to know the quantity of the material stored – as, e.g., cement for the production of building materials. Only if the actual stock is known, supplies may be ordered early enough thus avoiding any shortage in supply or production bottlenecks.
Level measurement – simple and accurate
The measuring instrument basically consists of an electromechanically driven reel, a rope and/or a tape and a sensing weight fixed at the end. The instruments are mounted on the roof of the silo. When lowering the sensing weight into the container, the tape and/or the rope are wound off the reel until the sensing weight rests on the material to be monitored. The rope tension indicates if the sensing weight is already in contact with the bulk material. When winding up again, the revolutions are counted as well. In this way, the measured value is verified and simultaneously determined whether the sensing weight is returned to its starting position.
The plumb bob technique is especially suitable for these applications because any dust inside the silo neither influences the results of the measurements nor the conductivity of the bulk material. Changing moistures of the bulk materials and adherent materials are not a problem for the measurement method either.
Features inside
The instrument is accommodated in an aluminum housing (IP66) and is suitable for ambient temperatures ranging from - 40 to + 80° C. An additional weather protection cover provides shelter against extreme climatic influences. As to avoid any contamination of the electronic equipment, the electronic and the mechanic are strictly separated from each other in the device. Alternatively a version with rope is offered, being, in particular, suitable for dry products, and a version with measuring tape for sticky products and automatic tape cleaning. The instruments are available for supply voltages of 230 V or 115 V AC as well as 24 V DC. Measuring ranges of up to 30 meters can be realized. It is possible to measure any materials from a density of 300 g/l. An optional spike on the sensing weight prevents the weight from slipping down or tilting at steep angles of repose, e.g. in case of powders. Due to the ATEX and FM certification the instrument may also be used in dust explosion-prone areas.
In the meantime, the Nivobob 4000 has proved successful in various pilot projects. The instrument has now been presented at the Powtech and is available all over the world from. As it is possible to make the measured data available on the computer, the order logistics can also be simplified.
