# UL 555S — Which OSHA NRTL is recognized for which test standard: all 21 labs' scopes of recognition, cross-referenced

For UL 555S, laboratory is UL LLC; standard title is Leakage Rated Dampers for Use in Smoke Control Systems, verified against its source on 2026-08-10.

- **Laboratory:** UL LLC _(verified: appears in the quote below)_
- **Standard number:** UL 555S _(verified: appears in the quote below)_
- **Standard title:** Leakage Rated Dampers for Use in Smoke Control Systems _(verified: appears in the quote below)_

## What the source says

> UL 555S | Leakage Rated Dampers for Use in Smoke Control Systems |

## Source

- https://www.osha.gov/nationally-recognized-testing-laboratory-program/ul

Last verified: 2026-08-10. Review by: 2026-12-08.
Part of [Which OSHA NRTL is recognized for which test standard: all 21 labs' scopes of recognition, cross-referenced](https://referencesource.org/nrtl-recognition-scopes/).