14-Feb-2012

Simplify moisture measurement

Inline moisture sensor connected to fluid bed processor

GEA Pharma Systems, in co-operation with NDC, has developed an inline moisture sensor for pharmaceutical drying systems that simplifies moisture measurement and saves processing time, while avoiding unnecessary operator contact with toxic compounds.

The LHP-NDC 710e, which fits into a standard 2in port on the dryer, extracts the moisture content as a single piece of information and displays it simply for the operator.

Using standard techniques, samples of dried powder must be taken manually from each batch of powder and tested off line in a laboratory to establish when the correct moisture contact has been achieved. This is time consuming, requires the dryer to be stopped and to wait while the test is performed, and runs the risk of the target moisture level being overshot and ending up with a product that is too dry and difficult to handle efficiently. Validated systems are susceptible to many outside influences, such as atmospheric conditions, which means that the moisture level can vary even if the process itself is constant.

GEA Pharma Systems’ new sensor, however, shows a continuous display of the actual moisture content on a display screen as the product dries. This allows the operator to stop the drying process at exactly the right point.

In addition the standard technique only provides a snapshot of the condition of a limited amount of product (5–10g), while the LHP-NDC 710e is capable of monitoring the complete drying cycle. The total amount of analysed product during the process cycle is estimated to be more than 1,000g.

When first installing the LHP-NDC 710e it is necessary to perform a simple calibration exercise to compare the reading on the sensor to actual readings from laboratory tests. These need to be done for each product to be dried. Once the calibration line has been plotted the instrument remembers the settings and continues to show accurate moisture levels for each product. As this is a display of the actual moisture level in the powder it is unaffected by atmospheric conditions or other variables.

The Lighthouse Probe, also from GEA Pharma Systems, is particularly useful when working with wet or sticky products when it is essential to have a clear view of the product. Conventional windows can easily become fouled when processing these types of products. The Lighthouse Probe uses an in-line window wash to keep a clear view at all times.

Dr Harald Stahl, senior pharmaceutical technologist at GEA Pharma Systems said the timesavings for each product batch could be significant.

‘Every time a batch is tested manually it can take 10–15 minutes. Sometimes batches have to be tested more often. The real risk is that the final moisture content is too low. In this case it’s possible that the whole batch could be rejected. The new sensor avoids this problem and ensures that the target moisture content is achieved every time.’

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