Pre-freezing operation of centrifugal laboratory freeze dryer

Pre-freezing operation of centrifugal laboratory freeze dryer
A small amount of products in the laboratory freeze dryer are generally pre-frozen in the cold trap cylinder. The flask needs to be equipped with a cold bath with a freezing device to pre-freeze into a shell structure. The ampoule can be pre-frozen in the refrigerator or pre-frozen with a centrifugal attachment. The vials are generally pre-frozen in a low-box refrigerator.
The laboratory freeze dryer with centrifugal attachment pre-freezes the product by vacuum refrigeration, placing the mounted ampoule on a rotatable support and rotating at 800-1000 rpm, at the same time Vacuuming, the centrifugal force generated during rotation prevents the air dissolved in the product from emerging under vacuum. When the vacuum reaches a certain value, the product absorbs its own heat due to the rapid evaporation of moisture in the product, and the product freezes quietly. Ice and form a beveled shape.
When the vial is pre-frozen, the half-pressed bottle should be placed on the plate with the support, and the bracket and the layer should be pre-frozen in a low-temperature refrigerator. At the end of the pre-freezing, the cold trap should be cooled first. When the temperature of the cold trap reaches -40 °C, the lamellar support with the product is quickly taken out from the low-temperature refrigerator, the cold trap cover is opened, and the lamellar support with the product is transferred into the cold trap. And immediately start the vacuum pump, evacuate the cold trap, so that the product will immediately sublimate under vacuum, and absorb heat to keep the product at a low temperature. If the action is slow, the product will heat up and melt.
The product pre-frozen in the cold trap barrel is the same as the pre-freezing transfer method in the refrigerator. In fact, the product is transferred from the bottom of the cold trap to the upper part and immediately evacuated; otherwise, it is difficult to obtain heat when the product is sublimated, which will prolong the drying time. .
When the flask is lyophilized, the bell jar with multi-manifold is placed in advance, the cold trap is cooled and the vacuum is drawn. At this time, the frozen flasks are quickly connected to the valve one by one, and the valve is rotated to evacuate the flask. The valve on the multi-manifold is a special valve. The rotary handle has four positions. When the rotary handle is turned to the left and right, the closed flask interface is connected with the venting port; when the rotating handle is downward, the closed bell jar is connected with the venting port. Open the bell jar and the flask interface; when the rotary handle is up, the bell jar is closed to the flask connection, and the flask is connected to the atmosphere (the atmosphere is placed in the flask so that the flask is removed after drying).
The ampoules pre-frozen with the centrifugal attachment do not need to be converted. After the vacuum reaches a higher value, the product is already frozen. Just turn off the motor of the centrifugal rotor, as the product is already sublimating.