The most frequently asked questions pre-sales and after sales
What is a freeze dryer (lyophilizer)?
A freeze dryer removes water from frozen materials via sublimation (solid ice → vapor, no liquid) under vacuum, preserving products color, structure, biological activity, flavor, and nutrients.
What is the core parameter of a freeze dryer?
The most crucial technical parameter of a freeze dryer is its shelf area (㎡), which effectively reflects the size and processing capacity of the machine. Shelf area vs. processing capacity: The international standard is: 1㎡ = 10kg
What is the working principle of freeze drying?
Freeze drying (lyophilization) works on the core principle of sublimation - turning ice directly into water vapor without melting into liquid water.
How long does freeze-drying take?
The time required varies depending on the manufacturer and the machine's performance. Even within the same manufacturer, different types of machines have varying performance. The time required also differs depending on the product being processed. Furthermore, the time required varies depending on the size of the same product. Setting different heating temperatures also affects the production time. Here are some examples for reference only: 1. Candy: 2-4 hours 2. Indian rice: 8-12 hours 3. Sliced fruit: 18-24 hours 4. Probiotics: 48-72 hours
What temperature range is required?
Product cooling: Below the eutectic point temperature, typically -20°C to -40°C. Cold trap cooling: Below the product temperature by 10°C, typically -30°C to -50°C.
In addition, -70°C option is available.
What vacuum level is required?
Standard vacuum levels for freeze drying • Food: 20–100 Pa (faster) • Pharma/Bio: 1–20 Pa (ultra‑low) • General working range: 20–80 Pa (most common)
What is the CIP?
CIP stands for Clean In Place. It's a function that automatically cleans the shelves of a freeze dryer without requiring an external movable water hose.
What is the SIP?
SIP means Sterilization in Place. It is a function of sterilization by high temperature and high pressure steam inside the freeze dryer chamber; It is used for freeze drying viruses and bacteria. Steam SIP is not available for option.
What is cold trap/vapor condenser?
Cold trap: called vapor condenser, one component, two names; it's one of the core components inside the freeze dryer chamber. It is used to condense vapor sublimated from frozen products and protect vacuum pump.
What's the difference between 'in-situ' and 'IQF' freezing?
In-situ: Called freeze in place; freeze + dry in the same chamber.
IQF: Freeze in a cold room, and dry in a vacuum chamber.
What is the difference between food and pharma freeze dryers?
Food freeze dryer: Large capacity, fast production, 304 stainless steel, high efficiency, low energy consumption. Pharma freeze dryer: SIP sterilization, precise control, CIP, GMP, FDA, 316L steel, data logs, high energy consumption.
Why silicone oil is used in some freeze dryers?
Silicone oil is only used in freeze dryers with in-situ freezing function. It requires the shelf to have both freezing and heating functions. Water freezes at 0°C, no fluidity, and it cannot transfer cold energy. Silicone oil has a wide temperature range: -80°C to 150°C, and is non-corrosive to most materials.
How to choose freeze dryer capacity?
Based on fresh products feeding capacity kg per batch or shelf area (m²) . The shelf area (m²) is more accurate to describe the size of a freeze dryer.
How to choose air-cooled or water-cooled freeze dryers?
Air cooling involves using an air-cooled condenser; water cooling involves using a water-cooled cooling tower and water pump; both are used to cool the refrigerant. Air cooling is used in cold countries, such as Russia, Finland, Norway, Sweden, Denmark, and Canada etc.; water cooling is used in tropical regions, such as Singapore, Malaysia, Indonesia, Thailand and India etc.
What are the 3 core stages of freeze drying?
Pre-freezing: Cool material below its eutectic temperature (typically −20°C to −50°C) to solid status.
Primary drying (sublimation): Reduce pressure; apply heat to sublime ice → vapor (captured by cold trap).
Secondary drying (desorption): Raise temperature slightly to remove bound/unfrozen water (residual moisture <1–3%).
What is the eutectic point?
Eutectic point: Temperature where solids and liquids coexist; It must stay below this temperature to avoid incomplete freezing.
What is the Co-melting point/collapse temperature?
Co-melting point: It's co-melting temperature, as well as collapse temperature; Temperature where porous structure fails (melts/shrinks); drying temperature must stay below this.
