1、 Preparation before device startup
1. Environment and Installation
The equipment should be placed in a ventilated area for easy heat dissipation and exhaust, with an ambient temperature of ≤ 32 ℃ and humidity of ≤ 80%.
Installed by a professional electrician, ensure that the vacuum pump rotates in the same direction as the calibration direction.
Grounding protection: The equipment must be reliably grounded to prevent static electricity from damaging components or causing electric shock.
2. Key component inspection
Vacuum pump: Check if the oil level meets the standard (up to the centerline of the sight glass), and replace if the oil is cloudy.
Sealing: Confirm that the water outlet valve is tightened, the inflation valve is closed, and there is no dirt on the contact surface between the organic glass cover and the rubber ring.
Cold trap and pipeline: Check that the condenser fan, connecting pipeline, and pressure gauge are in normal condition.
2、 Pre freezing stage operation
1. Material pretreatment
The material needs to be completely frozen (usually ≤ -50 ℃) to prevent residual liquid from vaporizing and spraying under vacuum.
The slice thickness is uniform, and it is loosely spread on the material tray. The loading amount should not exceed the standard, and the loading time should be shortened as much as possible.
2. Pre freezing process
Preheat the refrigeration unit for at least 2 hours, and only add materials when the temperature of the cold trap reaches -25 ℃ or below.
The pre freezing temperature and time are adjusted according to the characteristics of the material to ensure uniform formation of ice crystals.
3、 Drying stage operation
1. Vacuum start
After closing the compartment door, start the vacuum pump and monitor the vacuum degree to be ≤ 15Pa (normal range).
The vacuum pump should be placed below the level of the freeze dryer to prevent oil return.
2. Temperature control
One drying session: Control the temperature to about -10 ℃ to avoid temperature fluctuations affecting nutrient retention and color.
Analysis of drying: Gradually increase the temperature (≤ 30 ℃) to remove bound water, with a final moisture content of ≤ 5%.
4、 Key points of safety and maintenance
1. Operational safety
The temperature of the cold trap is about -65 ℃, and it is necessary to wear insulated gloves to prevent frostbite during operation.
Overloading operation is prohibited, with a continuous working time of ≤ 48 hours.
After a sudden shutdown, restart the refrigeration unit with an interval of at least 3 minutes.
2. Cleaning and maintenance
At the end of the batch, defrosting and drainage are required: after the cold trap is completely melted, open the water outlet valve and clean the inner wall with a dry cloth.
Regularly disinfect the interior of the equipment and check the stability of the refrigeration unit and vacuum pump performance.
5、 Prohibited items
1. Materials are prohibited from containing acids, bases, or volatile organic solvents to avoid corrosion of equipment or accidents.
2. Do not cover the heat dissipation port and avoid operating in environments with temperatures above 28 ℃.
By standardizing operating procedures and regular maintenance, it is possible to ensure freeze-drying efficiency and nutrient retention rate of pet food (such as vitamin loss rate<5%), while extending equipment lifespan.