UL 521 · FM
For UL 521, nrtl is FM; standard title is Heat Detectors for Fire Protective Signaling Systems; laboratory is FM Approvals; osha docket is OSHA-2007-0041; status is currently recognized, recorded from its source on 2026-10-01; source re-checked 2026-11-10.
- Test standard
- UL 521 verified
- Standard title
- Heat Detectors for Fire Protective Signaling Systems verified
- NRTL
- FM
- Laboratory
- FM Approvals
- OSHA docket
- OSHA-2007-0041 verified
- Status
- currently recognized our reading
Values marked our reading are our classification of what the source says — the source does not print them in those words. The quote below is the evidence for each one; judge it yourself.
What the source says
UL 521 | Heat Detectors for Fire Protective Signaling Systems |
— osha.gov, retrieved 2026-10-01
Where each value comes from
The value above is stated away from the sentence quoted with the answer, so the passage that states it is shown here too.
OSHA docket
Docket Number: OSHA-2007-0041
— all from osha.gov, retrieved 2026-10-01
Source
- osha.govhttps://www.osha.gov/nationally-recognized-testing-laboratory-program/fm