Take an Amerex B402 and an Amerex B424 down from the same wall and you are holding two 5 lb ABC dry chemical extinguishers from the same factory, filled with the same agent, each wearing a 195 PSI gauge. Now order rebuild parts for one from the other's parts list and nothing you receive will fit. Not the gauge, not the valve stem, not the spring, not the collar O-ring, not the lever, not the downtube — not even the hose.
Amerex's dry chemical hand portables are really two parallel lines — aluminum valve models and brass valve models — that share no valve parts at all. Knowing your extinguisher's size and agent but not its valve family is the single fastest way to order the wrong Amerex part. Here is how to tell which family you have, and a two-column cross-reference of every part that differs.
The Parts Book splits on the valve, not the size
Amerex's own Portable & Wheeled Parts Book doesn't organize dry chemical parts by capacity or by agent. It organizes them by valve. The table of contents lists "DRY CHEMICAL - 5, 5½, 6, 10, 20 LB. (Hose & Horn - Aluminum Valve)" and "DRY CHEMICAL - 5, 6, 10, 20, 30 LB. (Hose & Horn - Brass Valve)" as entirely separate parts lists, with a third for "DRY CHEMICAL HIGH FLOW - 10 - 20 LB. (Hose & Horn - Brass Valve)" and a fourth for the small fixed-nozzle aluminum valve units.
The aluminum valve family: the fixed-nozzle 376, 377, B410, B416 and B417, and the hose-and-horn B402, B500, B443, B479, B456, A411 and A413. All of them run the same valve internals.
The brass valve family: the B424, B461, B441, B460, 423, 415, 692 and 693, plus the High Flow line — 720, 722, 760 and 762. Inside this family the valve interchange is total: the Parts Book assigns one "Valve Assembly - ALL MODELS" (11952) and one "Lever & Rivet - ALL MODELS" (07762) to everything from the 5 lb B424 to the 30 lb 693.
Between the families, the interchange is zero. Wherever the two valves come near each other in the Parts Book, Amerex labels each split part explicitly — "Collar O-Ring - Aluminum Valve" against "Collar O-Ring - Brass Valve" — and carries the same split through its other stored-pressure hand portables, cataloging springs as "Spring - All Aluminum Valve" and "Spring - All Brass Valve."
The trap: twin models at almost every size
What makes this genuinely easy to get wrong is that Amerex builds both families in the same capacities and agents. These are the pairs, exactly as the Parts Book describes them:
| Capacity and agent | Aluminum valve model | Brass valve model |
|---|---|---|
| 5 lb ABC | B402 (and B500) | B424 |
| 6 lb ABC | B443 | B461 |
| 10 lb ABC | B456 | B441 |
| 10 lb Purple K | — | B460 |
| 20 lb ABC | A411 | 423 |
| 20 lb Purple K | A413 | 415 |
| 30 lb ABC / Purple K | — | 692 / 693 |
The 5 lb row is the easiest place to go wrong. Search for "Amerex 5 lb ABC gauge" and both the 03103-P and the 03965-P are correct answers — for different extinguishers. The model prefix won't save you either: B402 and B424 read like neighbors in the same series, and the letters in Amerex model numbers encode other things entirely — we cover what they do mean in Decoding Amerex Model Numbers.
How to tell which family yours is
Read the model number off the nameplate. That is the definitive answer. Find it on the label, match it to the rosters above, and every part on your extinguisher is decided. This is exactly how the Parts Book itself works — each parts list opens with the models it serves, and nothing off-list applies.
Amerex's current portable extinguisher catalog draws the same line, and tells you what the two builds are for. It specs the dry chemical line under two valve types — "BRASS VALVE—Heavy Duty," with a "chrome-plated brass valve body" and "stainless steel handle & lever," and "ALUMINUM VALVE—Light to Medium Duty," with an "anodized aluminum valve body" and "anodized aluminum handle & lever."
If you want to confirm what you're looking at, be careful with color: the valve names describe the metal underneath, but the brass valve body is chrome-plated, so both valves can read as plain silver metal at arm's length. The more reliable hardware tell is the carrying handle: the Parts Book lists a single "Rivet Only for Handle" for aluminum-valve models, while the brass-valve handle takes "Rivets Only for Handle (2 Required)." Two rivets through the carrying handle is a brass valve.
What you should not do is match parts by eye. Both families wear a gauge that reads 195 PSI, both seal the collar with an O-ring, and both stems do the same job. Amerex assigns them different part numbers because they are different parts.
The cross-reference: every valve part that differs
The stakes here are spelled out on the first page of the Parts Book: "To protect the UL listing and to keep the warranty in effect Amerex replacement parts must be used" — and, in capitals, "DO NOT SUBSTITUTE." The right Amerex part for the wrong Amerex valve is still the wrong part. Here is the full split, with the Parts Book's own numbers:
| Component | Aluminum valve (376/B417/B402/B456/A411 family) |
Brass valve (B424/B441/B460/423/415/692/693 + High Flow) |
|---|---|---|
| Gauge, 195 PSI | 03103-P | 03965-P |
| Valve stem assembly | 06092-P | 06093-P |
| Valve spring | 01074-P | 00383-P |
| Collar O-ring | 05241-P | 05240-P |
| Lever & rivet | 11825 | 07762 |
| Rivet only, lever | 01060-P | 01563-P |
| Handle & rivet | 11826 (5–10 lb) / 12405 (20 lb) | 09020, all models |
| Rivet only, handle | 01064-P (5–10 lb) / 12201-P (20 lb) | 01564-P (2 required) |
| Complete valve assembly | 11823 (5–10 lb) / 11824 (20 lb) / 27334 (fixed nozzle) | 11952, all models |
| Hanger loop with screw | 14220 | 15363 (10 lb) / 16694 (5, 6, 20 lb) / 17144 (692, 693) |
Note the pattern in the collar O-rings and stems: 05240-P and 05241-P, 06092-P and 06093-P. One digit apart, easy to transpose, and the reason it pays to confirm the valve family rather than trust a number remembered from the last rebuild. If you're weighing whether a rebuild makes sense at all against replacing the unit, we've run those numbers in Recharge or Replace.
Hoses and downtubes follow the same split
The split doesn't stop at the valve. The Parts Book gives the aluminum-valve B402 a 14849-P hose and horn assembly with a .157 orifice; the brass-valve B424 takes the 03753 at .140. At 10 lb, the aluminum B456 runs the 05564-P (.191) while the brass B441 and B460 share the 06095-P (.152). Downtubes diverge the same way: 06212 serves the B402, B479 and B500, while the B424 takes its own 01696 downtube and retainer assembly, the B441 and B460 the 02609, the 415 and 423 the 01667, and the 30 lb 692 and 693 the 09583.
Aside from commodity hardware the two lists share with the rest of the catalog — the 00160-P ring pin, its 00532-P chain, the 01387-P lock wire seal, the 15747-P hose strap — there is no component behind the nameplate where the two 5 lb ABC twins meet. Every rebuild decision starts with the valve family. So does recharging: fill adapters follow the same aluminum/brass split.
One caveat: the gauge follows the model, not just the valve
Within the brass family, don't over-generalize on gauges. The standard brass models and the High Flow 720, 722, 760 and 762 all take the 03965-P 195 PSI gauge — but the high performance and Z-Series dry chemical models in the Parts Book, which are also built on the brass valve and share the 06093-P stem, 00383-P spring and 05240-P collar O-ring, run at higher operating pressure and wear the 05225-P 240 PSI gauge behind a 09102-P chrome-plated brass gauge guard, with their own 09840 lever. The same is true in miniature on the aluminum side, where the 1 lb 376 takes a 125 PSI gauge (27611-P) instead of the 03103-P.
The working rule: stem, spring and collar O-ring follow the valve family; the gauge — and, on the high performance line, the lever — follows the exact model. When a gauge is what you need, confirm the model number, not just the valve metal.
What we stock
Aluminum-valve service parts — the 03103-P gauge, 06092-P valve stem, 01074-P spring, 05241-P collar O-ring and 11825 lever and rivet.
Brass-valve service parts — the 03965-P gauge, 06093-P valve stem, 00383-P spring, 05240-P collar O-ring and 07762 lever and rivet, along with complete valve assemblies, handles, hanger loops, hoses and downtubes for both families in Valves, Gauges & Downtubes, O-Rings, Seals & Pull Pins and Handles, Levers & Carriers — part of 495 Amerex part numbers in Service Parts.
The extinguishers themselves — both 5 lb ABC twins, the B402 and the B424, with the rest of both families in ABC Dry Chemical and the brass-valve Z-Series line in High Performance ABC.
Not sure which family your unit belongs to? Send us the model number off the nameplate — or a photo of the label — and we'll come back with the exact part numbers, availability and lead time: request a quote.
Sources
Model rosters, part numbers, fitment, gauge pressures and orifice sizes above are taken from Amerex Corporation's Portable & Wheeled Parts Book (Part No. 27277 Rev. C), which Amerex publishes "as a guide to assist qualified personnel in the proper selection of parts." Valve construction, operating pressures and the Heavy Duty / Light to Medium Duty descriptions come from Amerex's Portable Fire Extinguisher Catalog. Amerex notes that it "does not service, maintain or recharge fire extinguishers," and neither do we — parts should be installed by qualified fire extinguisher service personnel. Before ordering, confirm the model number against your extinguisher's own nameplate and Amerex's current documentation, and direct maintenance questions to a qualified fire protection professional and your authority having jurisdiction.
ShopAmerex.com is owned and operated by Centurion Holdings Group LLC, an independent authorized distributor of Amerex Corporation products. We sell equipment and factory OEM service parts — we do not perform inspection, service, hydrostatic testing or recharging.