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27
Feb
Backup Systems for ULT Freezers: Your Reliable Safeguard
Ensuring research continuity and sample integrity in Ultra-Low Temperature environments.
Think about the valuable samples stored in your ULT freezer. Losing them due to power failure or equipment malfunction would be devastating. Without a backup system, you are relying entirely on continuous power and flawless equipment performance—neither of which is guaranteed.
Backup systems provide critical protection. Below, we explore available options, how they work, their differences, and when to consider one.
When should you consider getting a Backup System?
If your ULT freezer stores critical or irreplaceable samples, a backup system is strongly recommended. Consider one if:
- ✓ Your facility experiences frequent power outages
- ✓ You store clinical or unique biological samples
- ✓ Research continuity is essential
Important: Backup systems typically must be factory-installed when the freezer is manufactured. Retrofitting later is rarely possible, so decide at the time of purchase.
Types of Backup Systems
CO2 Back-Up Systems
CO2 systems maintain temperatures between -50°C and -70°C, suitable for non-critical ultra-low needs.
They use liquid CO2 with a siphon tube to draw liquid from the tank bottom. CO2 remains pressurized and can stay connected for months without loss if unused.
A standard 50 lb cylinder can maintain a freezer (¾ full to full) at -60°C for about 8 hours, depending on size and conditions. Tanks must be replaced every 8 hours during use, or manifolded together for longer runtime.
LN2 Back-Up Systems
LN2 systems can maintain temperatures as low as -85°C, ideal for stricter temperature requirements.
Unlike CO2, LN2 continuously boils off—even when not in use—so a connected tank will empty within 6–8 weeks.
A fresh 160L cylinder can maintain a freezer at -60°C for 45–50 hours, depending on conditions. If continuously connected, tanks typically require replacement every 3–4 weeks.
Best practice is to:
- Connect the freezer to a remote alarm system
- Have trained personnel attach and activate a fresh LN2 tank upon receiving an over-temperature alert
This minimizes LN2 waste while ensuring rapid emergency response.
Backup Compressor
A backup compressor system includes two independent cooling circuits, each capable of maintaining ultra-low temperatures.
If one compressor fails, the other continues operating, preventing total system failure. This redundancy enhances reliability and durability.
Note: It does not protect against power outages. If power is lost, both compressors stop.
The temperature curve of -90°C normal setting.
Key Differences to Consider
| Feature | LN2 Systems | CO2 Systems |
|---|---|---|
| Temp Range | -80°C to -85°C | -50°C to -70°C |
| Handling | Active Management required | Easier to store/handle |
| Cost | Typically more expensive | Lower maintenance & cost |
| Protection | Power Outages & Mechanical | Power Outages & Mechanical |
*Note: Backup compressors only protect against mechanical failure, not power outages.
Maintenance Considerations
Proper maintenance reduces strain on compressors and extends freezer life. Key tasks include:
- Cleaning filters and condensers
- Wiping and checking seals
- De-icing valves
- Defrosting
- Replacing damaged parts
Always follow manufacturer guidelines and ensure personnel are properly trained. Improved efficiency not only extends equipment lifespan but also slows warm-up time during power loss. Staff should also be properly trained in handling CO2 and LN2 systems safely.
CO2 and LN2 Precautions
⚠ WARNING: If a cylinder falls and the valve breaks, it can become a dangerous projectile. Always transport with secured carts and anchor cylinders to a fixed structure.
⚠ WARNING: Liquid CO2 and LN2 are extremely cold and can cause severe burns. Wear protective clothing and eye protection.
⚠ WARNING: Evaporated gas can displace oxygen and cause asphyxiation. Never store cylinders in enclosed or underground spaces.
Biofargo team
