SAFE® Closure Systems FAQ –
Sealing, Thread Types & Automation
SAFE® closure systems from LVL technologies are safety-critical components for 2D tubes, used in cryogenic storage, biobanking, diagnostics, and laboratory automation. This FAQ addresses key questions on sealing, internal vs. external threads, screw caps, push caps, and manual, semi-automatic, or fully automated capper/decapper systems.
Selecting the appropriate closure system significantly impacts the sealing performance, contamination control, and process stability of SAFE® 2D tubes. For applications down to −196 °C, validated screw caps with defined torque and axial TPE sealing are used. This ensures reproducible compression, stable cryogenic properties, and reliable integration into automated workflows.
In high-throughput environments, properly matched SAFE® closure systems reduce manual intervention, minimize interface risks, and contribute to reliable, digitally traceable sample management.
Thread Types & Closure Variants
Internal-thread tubes have the thread inside the tube, with the screw cap engaging internally.
External-thread tubes have the thread on the outside of the tube body.
External threads reduce the risk of sample liquid entering the thread area, minimizing carryover and thread contamination, especially during repeated opening or cryogenic applications.
External-thread 2D tubes are ideal for cryogenic storage and applications requiring high contamination control, such as biobanking or GMP-like environments.
Internal-thread tubes can be used in standardized automation environments if contamination and cryo-stability requirements are met.
Screw caps are threaded closures applied with defined torque.
Controlled torque ensures reproducible compression and consistent sealing.
The sealing performance of SAFE® systems has been validated at 7 Ncm (SBS 96) and 15 Ncm (SBS 48 and 24).
Push caps are snap-fit closures without a screw mechanism.
They allow quick manual capping and are suitable for frequent-access applications with lower cryogenic requirements.
For long-term LN₂ applications, screw caps with defined torque are recommended.
Sealing & Cryo-Stability
SAFE® closure systems use an axial TPE sealing concept.
O-rings are deliberately not used, as elastomeric seals can lose elasticity or develop compression set under cryogenic conditions.
The axial seal generates defined compression without additional sealing components.
Cryogenic temperatures cause material contraction.
A technically matched closure system ensures that defined compression is maintained at −196 °C, preventing micro-leaks.
Validation tests confirmed no nitrogen ingress after 168 hours of LN₂ vapor exposure.
External-thread systems reduce the risk of sample liquid contacting the threads.
Combined with reproducible capping and automated handling, this further minimizes carryover effects.
Capper & Decapper – Manual to Fully Automated
SAFE® capper and decapper systems are available as manual, semi-automatic, and fully automated variants.
Depending on the system, single tubes or entire SBS racks (24-, 48-, or 96-position) can be opened or closed simultaneously.
Multi-channel cappers allow parallel capping of multiple tubes.
Benefits include:
- Even compression across all positions
- Reproducible torque
- Increased process speed
This is especially important in high-throughput environments.
Fully automated systems are suitable for high-throughput applications such as biobanking or screening workflows.
They reduce manual handling, increase reproducibility, and integrate into robotic processes.
Yes. SAFE® systems are designed for SBS rack formats and enable simultaneous handling of all positions in 24-, 48-, or 96-format racks.
Automated systems provide reproducible torque and uniform compression.
Validation tests included 15 automated open/close cycles.
Results showed:
- No leaks
- No damage to sealing surfaces
- No thread abrasion
Reproducible capping reduces the risk of inconsistently closed tubes and supports stable cryogenic storage.
Application & Selection
The closure system determines whether a 2D tube can be reliably processed in automated workflows.
Only defined thread geometry and reproducible torque enable stable integration into capper, decapper, and robotic systems.
Selection depends on:
- Storage conditions (e.g., LN₂ applications)
- Automation level
- Frequency of opening
- Regulatory requirements
For long-term cryogenic applications, screw caps with defined torque are recommended.
SAFE® components are validated as a complete tube–cap–rack system.
System coordination reduces potential interface risks such as:
- Inconsistent thread tolerances
- Variable sealing forces
- Rack position instability
This is particularly important in automated high-throughput environments.
