Not all compact fire extinguishers protect against the same fire classes. Many automotive, marine and RV-size extinguishers are marked 2-B:C, 5-B:C or 10-B:C; those markings are different from a multi-class A:B:C rating. This reference explains what the letters and numbers mean and compares exact First Alert and H3R MAXOUT models available through UsedRVParts.
Understand Class A, B and C before comparing an extinguisher
Ordinary combustibles
Wood, paper, fabrics and other materials that can leave glowing embers.
Flammable liquids
Examples include gasoline and oil. The numeral before B indicates a standardized test-fire performance class.
Energized electrical equipment
The agent is suitable for electrically energized equipment. C has no numerical rating in these designations.
Compare exact fire-extinguisher numbers and ratings
| MPN | Listed UL fire rating | Agent mass | Extinguishing agent |
|---|---|---|---|
| AUTO5 | 5-B:C | 1.4 lb | Sodium bicarbonate |
| KITCHEN5 | 5-B:C | 1.4 lb | Sodium bicarbonate |
| REC5 | 5-B:C | 2 lb | Sodium bicarbonate |
| GARAGE10 | 10-B:C | 2.5 lb | Sodium bicarbonate |
| AUTOMAR10 | 10-B:C | 2.5 lb | Sodium bicarbonate |
| MX100B | 2-B:C | 1 lb | Potassium bicarbonate |
| MX100R | 2-B:C | 1 lb | Potassium bicarbonate |
First Alert AUTO5, KITCHEN5 and REC5 have catalogued 5-B:C ratings. The larger GARAGE10 and AUTOMAR10 are catalogued at 10-B:C. H3R MAXOUT MX100B and MX100R are smaller 2-B:C units using potassium-bicarbonate dry chemical instead of the sodium-bicarbonate agent listed on the First Alert models.
A higher numeral before B represents a different tested Class B capacity; it is not the extinguisher's bottle weight or a guarantee of effectiveness in every situation. The agent type, installation environment, discharge characteristics and any required certification also matter.
Check the bracket and extinguisher condition
The product listings include mounting brackets, but a supplied bracket should not be assumed to fit the existing bracket or vehicle location. Compare the bottle diameter, retaining mechanism, attachment surface and available access. Follow the manufacturer's recommendations for securing a cylinder in a moving RV, and position required safety equipment where it is accessible.
Check the specific extinguisher label for pressure-indicator instructions, service date, physical damage, seal status and replacement requirements. A used extinguisher or a bottle with an uncertain service history should not be assumed serviceable merely because it appears intact.
Compare fire-extinguisher product photographs
These product cards link to current UsedRVParts records. Check each product for condition, availability, exact labeling and included bracket. Viewing and pickup, where offered, are by appointment in Kelowna.
Manufacturer and rating reference
For exact product ratings and installation details, consult the First Alert extinguisher product literature and H3R Performance MAXOUT documentation. Compare the actual cylinder's rating label to the manufacturer's current product information and applicable fire-protection requirements.