Vacuum Control Modes for H food Freeze Dryer
General
Vacuum Control Modes
The freeze dryer provides two different vacuum control methods for different drying requirements. Users can select the suitable mode according to the product characteristics and process requirements.
1. Heating Pause Control Mode
In this mode, the system does not actively regulate the chamber vacuum pressure.
The vacuum pump operates continuously, while the freeze dryer controls the sublimation rate by adjusting the heating process.
When the chamber pressure rises above the allowable range during drying, the shelf heating will automatically stop temporarily. After the vacuum pressure returns to the normal range, heating will resume automatically.
This control method is simple, stable, and suitable for most common food freeze-drying applications.
Typical advantages:
- Simple operation
- Stable drying performance
- Reduced air introduction into the chamber
- Suitable for fruits, vegetables, meat, pet food, and general food products.
2. Auto Vacuum Regulation Mode
In this mode, the freeze dryer actively regulates the chamber vacuum pressure automatically.
When the chamber vacuum becomes lower than the target vacuum value (vacuum too high), the air inlet (bleed) valve will automatically open slightly to introduce a controlled amount of outside air into the chamber. This allows the system to maintain the chamber pressure near the preset vacuum value.
During operation, the vacuum pressure will fluctuate slightly around the target value, which is a normal operating condition.
This mode provides more precise vacuum control and can improve drying stability for sensitive products.
Typical advantages:
- More stable chamber pressure
- Better control of sublimation rate
- Suitable for products sensitive to collapse or foaming
- Improved consistency for some high-sugar or high-moisture food products
Notes
- Slight vacuum fluctuations during automatic regulation are normal.
- Excessive air leakage may affect vacuum control performance.
- For most standard food freeze-drying applications, Heating Pause Control Mode is sufficient.
- Auto Vacuum Regulation Mode is recommended for products requiring more stable process conditions.