UL Class III, FM-200, and Biometrics: A Plain-English Guide to Vault Security

Vault operators love to list certifications and security features — but what do these terms actually mean? Here's a plain-English breakdown of the most common ones, so you can evaluate claims with confidence.

UL Class III. Underwriters Laboratories (UL) is a US safety certification body that also tests vault and safe security in globally recognised standards. Class III is one of the highest ratings — it means the vault body and door have been tested against sustained attack using tools including drilling, cutting, and impact. A vault rated UL Class III has resisted at least 30 minutes of net working time by skilled attackers with industrial tools. This is the same standard used by central banks and bullion depositories.

FM-200 (HFC-227ea). This refers to the fire suppression agent used in the vault. Unlike water-based sprinklers (which would destroy paper documents and potentially damage metal) or CO2 systems (which require evacuation), FM-200 suppresses fire by absorbing heat without damaging contents or depleting oxygen. It's the gold standard for archive and vault fire suppression.

Biometric access. This broadly means using physical characteristics — fingerprints, iris scans, or hand geometry — to verify identity before granting vault access. Biometrics eliminate the risk of stolen key cards or memorised PINs. The strongest implementations combine biometrics with a PIN and a physical token (three-factor authentication).

24/7 monitoring. This should mean live human monitoring, not just recorded CCTV. Ask specifically: is someone watching the feeds at 3am on a Sunday? Are motion alerts responded to by on-site security, or just logged?

Annual independent security audit. The most important word here is 'independent.' Internal audits are meaningful but limited. An independent audit by an accredited security assessor — who can test for vulnerabilities and report without commercial incentive to pass — is a fundamentally stronger assurance.

At Guardian, all our facilities hold UL Class III certification, use FM-200 suppression, and are monitored 24/7 with an on-site response team. We publish our independent audit summary annually — you can request the most recent report through your account manager.