What does UEL mean?

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Tags

1. #flame
2. #flammable
3. #higher
4. #limit
5. #concentration
6. #upper
7. #capable
8. #vapor
9. #highest
10. #called
11. #producing
12. #flash
13. #source
14. #percentage
15. #concentrations
16. #presence
17. #ignition