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Christ Freeze Dryers Equipped with WIPOTEC Weighing Technology High Precision Weigh Cells for Process Optimization

Martin Christ is one of the leading manufacturers of freeze dryers for the pharmaceutical industry. To supply their customers with the best systems available for optimizing the drying process, Christ manufacturing plants were equipped with the globally respected Weighing Technology from WIPOTEC.

By implementing this technology, operators know the weight loss of the product during the drying process and can draw the correct conclusions concerning the proper duration of the freeze dry period (sublimation).

"WIPOTEC has contributed significantly to our global success.“

For more than 60 years, Christ has been providing its customers a wide range of laboratory, pilot and production plants for all application and process requirements.

The company is dedicated to freeze drying as an economical and stable means of achieving longterm preservation, for example, as required for vaccines, drugs, fruit, vitamins, and plant extracts in vials, capsules, or cups.

The key to determining the ideal freeze dry process is defining the speed of the sublimation and the end of the drying process. To do this, weight samples must be taken during the entire drying process.

The collaboration between Christ and WIPOTEC has led to the development of the LyoBalance, a precision Weigh Cell that provides extremely high accuracy in the typical application range of -40 to +40 °C. The LyoBalance has a resolution is 0.001 gram for a weight range of 50 grams and provides the technical basis for the high precision capture of the individual weight values. The system includes a standardized bottle feed and an integrated lifting mechanism equipped with position detection. The control and evaluation is easy and conveniently performed through the intuitively operated LPCplus software.

Because of its space saving design, the Weigh Cell can be installed anywhere in a pilot or production freeze dryer for the entire length of the process flow.

For the weighing process, the sample is lifted from the surface by a gripping arm, weighed, and returned to the surface in the time intervals established by the operator. The drying curve is easily and reliably determined by observing the sample weight loss over time. The end of the drying process has been reached when there is no longer any drop in weight.

As all Weigh Cells from technology leader WIPOTEC, this model also operates on the principle of Electro Magnetic Force Restoration (EMFR). The basic principle can be compared to a simple beam balance. As the weight force is applied to one side of the balance, the coil installed on the other side of the balance is forced out of the magnetic field.

 An optical positioning system senses the smallest displacement and reports this to a high precision control system that readjusts the compensation current and restores equilibrium to the balance. This compensation current is measured through a precision resistor and further processed by a microprocessor system for immediate output as a digital weight value. 

Space saving – integrated Weigh Cell „LyoBalance“

Martin Christ GmbH - head office

Christ dry freezer

WIPOTEC EMFR Weigh Cells provide the decisive advantage of having a very short settling time. They are extremely fast and supply highly accurate weight values. Furthermore, they provide space and cost savings and are easily integrated into existing systems. On request, Wipotec Weigh Cells can be fitted with AVC Technology (Active Vibration Compensation).

AVC provides the foundation for accurate and instantaneous weight measurements even at sites that are subject to external disturbance sources (vibrations from machinery or local conditions).

Seeking the best possible solution to the oft-repeated customer demand for an effective and economic drying system for products with no loss in quality or esthetic degradation, Christ initiated the contact to Wipotec at a trade show for pharmaceuticals in the mid-1990s. WIPOTEC quickly proved to be a competent cooperation partner.

Project Manager Andreas Vihs and Jens Dieckmann, Head of Engineering & Validation at Christ, praise the WIPOTEC weighing technology as being "equally reliable as it is important as a component in our freeze dryers."

Both agree that the versatility has contributed significantly to the worldwide success of the units. Stefan Krippendorff, Head of Technical Plant Engineering, highlights the continuity of the ongoing cooperation.

Since the start of the project in 1994, the contact to WIPOTEC has always been through the same partner. This shows just how close and trusting the business relationship between the two high tech companies over the decades has become.

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