The article has been updated for the latest version of AMARU from 2020 and then for the new shelf system from 2023.
Logically, we often come across the question "What is the capacity of the AMARU freeze dryer?". The issue of capacity is not only a question for our machine, but for all lyophilizers. Many people would say that the capacity of a freeze dryer is determined by the shelf space. In some cases this is the truth, but it is not always the case. How can a lyophilizer be "overloaded"?
Ice holidng capacity of condenser
For all freeze dryers, the capacity of the condenser, or the amount of ice the unit can hold, is the limit. When there is too much ice, more is not captured and excessive wear on the vacuum pump occurs. In this case, it does not matter that the product trays can hold the material if the result is poor. This is especially the case for freeze dryers designed for drying products with low moisture content, such as herbs, flowers, etc.
AMARU has a proven capacity of 15 kg of ice, so you do not have to worry about this limit.
Spacing between shelves
Apart from the very small, table-top ones, all freeze dryers have shelves on which to load trays with product. Logically, if the shelves are close together, you cannot place taller products on them. This limitation applies mainly to laboratory machines where the product is dried in small bottles (vials).
AMARU has a shelf spacing of 45 mm (5-shelf system) rep. 35 mm for the 7-shelf system.
Shelf area
This is actually a contradictory limit of the first point. We simply hit the capacity limit when the product no longer fits on the trays. Herbs are a good example. These contain relatively little water but take up a lot of space. In practice, it is not possible to fill AMARU with enough herbs to hit any of the above limits.
The total area of the shelves in AMARU is approximately 0,85 m2. If a 7-shelf system is used, then 1.1 m2.
So how did we figure out that our lyophilizer has a capacity of 7.5 kg? Simply, the vast majority of the loadings we tested on the prototype were at this weight, so we can tell pretty well how long they last, whether they fit on the product trays and whether they make sense from an economic point of view. Of course, it is possible to load, for example, 10 kg of yoghurt that contains 90% water into the machine. The AMARU can also dry such a load, but it is good to think that the time needed for perfect drying increases with the quantity.