The Ci4 in the pharmaceutical and food industries: measurement accuracy and user-friendliness

Level measurement via differential pressure

Level measurement using differential pressure is a common method in a wide range of applications. In this process, the measured pressure readings and the specific gravity of the medium are used to determine the level. The diaphragm seal on the tank are connected to the transmitter via capillary tubes, and the diaphragms of the diaphragm seal transmit the pressure to the measuring device via a carrier fluid inside. The software uses the difference in pressure readings to determine the level with a high degree of reliability. In this case, diaphragm seal have the advantage of separating the medium from the pressure measuring device, thereby helping to meet the hygiene requirements in these industries.

LAB4Level menu navigation

The LAB4Level menu system also offers the advantage of a highly user-friendly method for recording tank data: whereas it used to be necessary to calculate the data for each tank through a time-consuming calibration process and then enter it manually, with LAB4Level the tank simply needs to be filled and emptied to obtain the table values, and the software handles the complex calculations and the creation of the table. The data from a tank that has been recorded once can also be easily transferred to tanks of the same design. This means avoiding errors in calculation and data entry and huge time savings for users: instead of one to two months, it now takes just one to two weeks to calibrate a system with 100 tanks.

Manufacturing processes in the pharmaceutical and food industries often involve fluctuating temperatures, which pose a fundamental limitation for the use of standard pressure transmitters: temperature fluctuations in the process lead to inaccuracies in the measurement result, known as temperature error. This occurs because the carrier fluid inside the pressure transmitter contracts when exposed to cooler temperatures. The result: the pressure acting on the diaphragm of the pressure transmitter is not transmitted correctly, so the tank is displayed as empty even though it is already full.

This effect occurs, for example, after a cleaning cycle: during CIP and SIP procedures, the tanks are sterilised at extremely high temperatures. Afterwards, the cooler products and liquids to be processed are filled into the tanks – and this is where the temperature error occurs.

LTC technology

The solution: Labom’s patented LTC (Low Temperature Coefficient) technology. This involves giving the diaphragm of the diaph a special profile and a slight curvature. This curvature means that the diaphragm seal has two natural resting positions – an upper and a lower one. In a special, patented manufacturing process, pressure transmitters with this diaphragm are filled in such a way that the diaphragm is positioned exactly between the two rest positions. The result: the diaphragm can be deflected in this position with virtually no force, thereby compensating even for large expansions of the carrier fluid.

Tube diaphragm seal

Another of Labom’s strengths lies in its customised process connections, designed specifically to meet the hygiene requirements of the pharmaceutical and food industries. These process connections are typically located at the bottom of the tank and are fitted using a welded adapter. The clamp connection, which is otherwise frequently used, is not ideal in this location as it results in a relatively large dead volume. Instead, Labom uses Tubus pressure transmitters (DRD Tubus Flange or Tubus Clamp), which are characterised by minimal process contact and a small dead volume. Furthermore, the diaphragm of these pressure transmitters is relatively large, which enhances the effect of LTC technology and thus improves measurement accuracy.

The Ci4, in combination with the LAB4Level level measurement software, LTC technology and a hygienic pressure transmitter system, is ideally suited for level measurement in the pharmaceutical and food industries.