The sublimation pressure on the freezee dryer, you need to know it

If you are learning about pressure on the freeze dryer, the content or information will be different from what is analyzed in this content, because sublimation pressure is the value that creates the pressure threshold for the dryer to provide heat for the product on the drying tray, thereby determining the sublimation of ice in the product. In this content, Mactech will analyze more carefully to help users understand this issue.

A freeze drying machine is a product drying device that relies on the sublimation of ice in deep cold conditions with the drying chamber pressure reaching an appropriate vacuum level. All products placed in the dryer will be frozen until they reach a cold temperature of -20^oC to -30^oC, which is appropriate, next, the drying chamber will be vacuumed until it reaches the sublimation pressure level, then the dryer will start to supply heat for the product. You need to understand this basically, the temperature on the product is initially at ambient temperature, after freezing, the temperature is about -25^oC, and finally when it reaches the appropriate dryness, the product temperature will return to 25 to 35^oc. So during the drying process, the product on the tray will gradually increase in temperature.

For the pressure drying method, the vacuum pressure level in the drying chamber is required to be lower than the sublimation pressure level for the controller to supply heat to the product to promote the strong sublimation process of ice more strongly. Because, when sublimation of ice increases sharply, the drying chamber pressure will increase, If this increase is not controlled, it will damage the dried product when the vacuum pressure is not guaranteed. Therefore, this pressure threshold is very important to maintain reasonableness between parameters during the product drying process.

When you choose the pressure drying mode, you only need to set the maximum sublimation pressure and T1 temperature values on the product. Choosing this drying mode will help the drying process be more optimal, faster and simpler to install than multi-stage drying. Normally, you should set the sublimation pressure at 50-60 pa, the T1 temperature should be at 30- 40^oC, then, if the AP value (actual pressure in the drying chamber) is higher than 50pa, the machine stops providing heat to reduces the sublimation rate. If the AP is always less than 50pa, the machine provides continuous heat to promote the sublimation rate for the ice in the product. And the temperature on the product never exceeds the T1 setting.

For example, when you dry cordyceps mushrooms, the final temperature on the product can reach 40^oC, you should set T1 to 40 degrees, and when you dry probiotics, you should only set T1 to 20^oC to avoid damaging the product, high temperature can kills microorganisms in yeast after drying.

This drying method is very effective when it is necessary to dry products with soft texture to ensure they are dry and crispy while still retaining their original shape, preserving color and preserving nutrition… such as drying vegetables to make vegetable powder, drying crispy fruits, drying medicinal herbs, drying mushrooms to keep their shape, drying powder solutions to obtain the loose, completely dry powder… Many products can use this drying method to get good results. If you need to dry fruits, dry them to make fruit tea, dry common things such as dried fish, dried meat, potatoes, dried bamboo shoots, dried fruits… then you should use hot air drying and cold drying will be suitable.

So with the above basic analytical information, Readers have a better understanding of what the sublimation pressure level is set when drying the product. Customers need detailed advice on drying products, please contact Mactech Việt Nam to be provided with appropriate information. Thank you for understanding the shared content.