The Shanghai Yetuo capping freeze-drying machine can also be used as a pharmaceutical freeze-drying machine. Its main function is to dry the product after desorption drying is completed. If the product is packaged in a tray, sterile air can be added to atmospheric pressure, and the box door can be opened for product release; It should be noted that dried products are prone to absorbing moisture from the air. Therefore, when tray products are shipped out of the box, the humidity of the sterile room air should be controlled. After the products are shipped out, they should be immediately isolated from the atmosphere to avoid affecting the residual moisture content of freeze-dried products.

Due to being dried under vacuum, freeze-dried products are minimally affected by oxygen. If air is released from the box, the oxygen in the air will immediately invade the gaps of the dried product, and some active groups will quickly combine with oxygen, causing irreversible effects on the product; To avoid the above situation, some products use inert gases, such as nitrogen sealing, while others use vacuum sealing.

Early freeze dryers did not have a device that could seal all bottles inside the freeze drying box, nor did they have suitable bottles and stoppers for sealing. After the products were released from the box, they had to be sealed bottle by bottle. If the ampoule is sealed one by one, it can be vacuum sealed while vacuuming, or nitrogen filled sealed after removing air with nitrogen gas; If it is a small bottle, it is necessary to manually plug the reversible stopper one by one, then insert the needle to evacuate, and seal the needle hole with sealing wax. The quantity of small bottles in each batch of products is huge and requires a lot of manpower. Later, a device for sealing small bottles inside a box and its matching small bottles and stoppers were invented. The stopper was positioned on the bottle mouth through a "semi pressure stopper" after the small bottle was packaged, and was pre frozen and dried together in the box. The stopper had a vent hole to allow sublimated water vapor to pass through. After freeze-drying, a mechanical device was used to press the stopper completely into the bottle mouth, isolating the small bottle from the outside world. The earliest stopper pressing device was a rubber bag type, with a middle layer above the board layer, in which a rubber bag was placed. Normally, the rubber bag was flattened in the middle layer by the force of a spring, and after freeze-drying was completed, air was added to the rubber bag. The rubber bag expanded in vacuum, and the stopper was pressed into the bottle mouth, which actually utilized the force of atmospheric pressure. Later on, there were screw type plug pressing devices that utilized the power of screws for plug pressing, and modern freeze-drying machines almost all use hydraulic plug pressing. The pressure plug design force is 1kg/cm2. The pressure plug inside the box has high requirements for small bottles, such as high dimensional accuracy of bottle height, bottle mouth diameter, bottle mouth roundness, etc. The small bottle should have uniform thickness and a certain strength, otherwise it may be crushed or affect the seal. The stopper should also have high precision, suitable rubber hardness, and a tight fit with the bottle mouth. The vent on the stopper should not be too small to avoid increasing sublimation resistance. The positioning at the bottle mouth should be reliable after half pressing the stopper. Stoppers are generally made of butyl rubber with poor breathability. In order to facilitate the transmission of the stopper on the semi pressure stopper machine and reduce the pressure stopper resistance, the stopper needs to be siliconized with a pharmaceutical silicone oil with a viscosity of about 350 cubic centimeters.