What Is the Best Way to Beat CO₂ Freezing of Padlocks to Gain Access?

Criminals have used liquid CO₂ or compressed gas to rapidly freeze small padlocks, then smash or shatter the brittle components to remove the lock. This attack targets the weakest internal parts — typically spring-loaded snap or single-bolt locking mechanisms — which become brittle at very low temperatures. The good news: with the right specification and a few simple site measures, you can make this attack impractical.

Why Some Padlocks Fail When Frozen

Many low-cost padlocks use spring-loaded locking bars (snap or single-bolt systems). These rely on polymer or spring-steel parts that can become brittle when exposed to CO₂ temperatures.
Once brittle, a heavy blow with a hammer or crowbar often severs or deforms the locking element and the shackle can be removed.
Small brass padlocks are particularly vulnerable because their internal mechanism is often a simple snap or single-bolt, and their bodies/shackles are not hardened.

What Makes a Padlock Resistant to CO₂ Freezing Attacks

Double ball-bearing locking: Hardened steel ball bearings engage deep grooves in the shackle. Even if the shackle is cut or chilled, the bearings hold the shackle in place and prevent rotation or easy removal.
Fully hardened shackles (boron or hardened alloy) resist cutting and maintain structural integrity at low temperatures.
Closed or shrouded shackle designs reduce exposed shackle length and make direct hammer or cutter access harder.
Robust bodies (hardened steel, Granit-style cases or Abloy/Protec designs) that transfer impact without failing.
Weatherproofing and sealed cylinders to keep lubrication and mechanism working in cold/wet conditions.

Practical Recommendations

Replace small brass snap-lock padlocks with high-security models that use double ball-bearing locking (look for wording such as “double ball bearing” or BB locking).
Choose hardened shackle materials (boron alloy or hardened steel) rather than soft stainless for cut resistance — note stainless resists corrosion but is softer.
Prefer closed/shrouded shackle or discus-style locks where the shackle is largely hidden.
Fit the lock inside a recessed lockbox or protected hasp/lock enclosure where possible so an attacker cannot apply CO₂ directly to the mechanism.
Use a high-quality, weatherproof lubricant (PTFE or graphite-based) and service locks regularly; a well-lubricated mechanism is less likely to seize when exposed to cold.
Combine a strong padlock with physical deterrents: shrouded hasps, hardened chains, alarmed hasps, tamper sensors or CCTV to increase the time and risk for the attacker.

Examples of Suitable Solutions

High-security ball-bearing padlocks (Granit / Abus Rock / Abloy Protec / Squire Stronghold).
Discus-style or shrouded padlocks fitted into protected hasps or lock boxes.
When the fitting allows, use a lockbox (welded or bolted) so the attacker cannot directly spray the padlock.

Quick Site Checklist

Replace small brass snap-locks with ball-bearing locks.
Fit padlocks in recessed lockboxes or behind shrouded hasps.
Use hardened shackles (boron/alloy) and closed-shackle designs where possible.
Add an audible alarm, CCTV or tamper-evident seals for added deterrent.
Maintain lubrication and inspect locks regularly.

Summary

CO₂ freezing attacks exploit weak internal locking systems and small, cheap padlocks. The most reliable defence is to specify high-security padlocks with double ball-bearing locking and hardened components, and to combine them with physical protection (lock boxes / shrouded hasps) and detection (alarms / CCTV). In short: upgrade the lock, protect the fitting, and make the attack noisy and slow.