ShopAmerex.com · Amerex 04938 datasheet · https://shopamerex.com/products/amerex-04938-downtube-assembly-stored-pressure-wheeled-unit · Figures as published by Amerex · Verified Sep 2, 2026
Genuine Amerex service part·Part no. 04938
Amerex 04938 Downtube Assembly, Stored Pressure Wheeled Unit
Amerex 04938 is the Downtube/Retainer Assembly used inside the agent cylinder of the Amerex 488 and 490 125 lb stored-pressure wheeled dry chemical extinguishers (Parts Book p.16, item 2), and is listed again for the Z-Series 690 and 759 (p.20, item 2) and the 150 lb Halon 1211 model 600 (p.22, item 28). Full overview ↓
- Part no.
- 04938
- Pack
- 1 (sold individually)
- Fits
- 488, 490, 759
- Parts Book
- Page 18
- Free shipping (orders over $100)
- Returns per our refund policy.
Genuine Amerex part from an authorized Amerex distributor. Not a generic substitute.
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Quotes for part lists, PO and tax-exempt orders, and parts not yet listed.
Which models does the Amerex 04938 fit?
Per the Amerex Parts Book · page 18| Fits | Extinguisher | UL rating | Capacity | Price | Link |
|---|---|---|---|---|---|
| Model 488 |  10488 Amerex 488 125 lb Wheeled ABC Fire Extinguisher (CG)Parts Book p.16 |
30A:240B:C | 125 lb (56.7 kg) | $5,737.00 | View |
| Model 490 |  10490 Amerex 490 125 lb Wheeled Purple K Fire ExtinguisherParts Book p.16 |
320B:C | 125 lb (56.7 kg) | $6,549.00 | View |
| Model 759 |  27065 Amerex 759 125 lb Wheeled Purple K Fire ExtinguisherParts Book p.20 |
120B:C | 125 lb (56.7 kg) | $12,112.00 | View |
Parts list for 125/150 lb. dry chemical stored pressure wheeled models
Fitment per the Amerex Parts Book. Check the part number against your unit’s nameplate before ordering.
What is the Amerex 04938?
Amerex 04938 is the Downtube/Retainer Assembly used inside the agent cylinder of the Amerex 488 and 490 125 lb stored-pressure wheeled dry chemical extinguishers (Parts Book p.16, item 2), and is listed again for the Z-Series 690 and 759 (p.20, item 2) and the 150 lb Halon 1211 model 600 (p.22, item 28). Amerex's 488/490 owner's manual identifies the downtube as the path that allows proper aeration of the dry chemical when the extinguisher is pressurized through the operating valve, which is why the manual forbids pressurizing through the bleeder valve. It is sold individually. Amerex's Parts Book notice states that Amerex replacement parts must be used to protect the UL listing and keep the warranty in effect.
Amerex 04938 specifications
| Part number | 04938 |
|---|---|
| Description | Downtube/Retainer Assembly |
| Parts Book page | 16 (PDF p. 18) |
| Diagram item | 2 |
| Pack quantity | 1 (sold individually) |
| Models | 488, 490, 690, 759, 600 |
|---|
| Amerex item number | 04938 |
|---|
Part data as published by Amerex. Confirm against the current Parts Book revision before ordering for a unit in service.
Amerex 04938 documents
Official Amerex publications · PDF- Parts Book p. 18 Downtube/Retainer Assembly — parts list for 125/150 lb stored-pressure wheeled models 488, 490 (printed p.16)
- Parts Book p. 22 Listed as "Downtube/Retainer Assembly - 690, 759" (item 2) on the Z-Series parts list (printed p.20)
- Owner's Manual (488/490)
- Owner's Manual (Z-Series 756/758/759)
- Tech Tip Why genuine Amerex parts
- Warranty
Current Amerex publications, hosted on ShopAmerex so links do not break when Amerex reorganizes its site.
Other parts on Parts Book page 18
Parts list for 125/150 lb. dry chemical stored pressure wheeled models · All 22 parts| Part no. | Part | Pack | Price | Quantity and add to cart |
|---|---|---|---|---|
| 03501 | 1 (sold individually) | $600.00 | ||
| 03556-P006 | 6 per pack | $14.99 | ||
| 03562-P001 | 1 (sold individually) | $11.99 | ||
| 03678-P001 | 1 (sold individually) | $505.00 | ||
| 05067-P001 | 1 (sold individually) | $17.99 | ||
| 05197 | 1 (sold individually) | $671.00 | ||
| 05239-P012 | 12 per pack | $53.99 | ||
| 06059 | 1 (sold individually) | $132.00 |
Item numbers refer to the exploded view on the Parts Book page. Model-specific items are marked in the Amerex parts list; confirm before ordering.
Amerex 04938 questions
What does the Amerex 04938 downtube assembly fit?
It fits the Amerex 488 and 490 125 lb wheeled dry chemical extinguishers (Parts Book p.16) and the Z-Series 690 and 759 125 lb units, which the Parts Book lists for the same downtube (p.20, item 2).
What does a downtube do inside a stored-pressure extinguisher?
Amerex's owner's manual states that pressurizing the extinguisher through the operating valve allows proper aeration of the chemical through the downtube, and cautions against using the bleeder valve to pressurize the unit.
Is the Amerex 04938 a genuine Amerex part?
Yes. It is the factory Parts Book item; Amerex's parts notice states that genuine parts are required to protect the UL listing, and substitute parts void the warranty.
Does it come as a kit with the valve?
Amerex's Complete Valve Assembly (item 1 on the same page) already includes a downtube/retainer assembly; 04938 is the standalone replacement for servicing an existing valve.
Where is the 04938 listed in the Amerex Parts Book?
Printed page 16, item 2 of the 488/490 parts list (PDF page 18); it also appears on printed page 20, item 2, for the Z-Series 690 and 759, and on printed page 22, item 28, for the Halon 1211 model 600.
Does replacing the downtube require depressurizing the extinguisher?
Yes. Amerex's owner's manual warns that valve removal and valve part replacement shall be made only after completing the depressurizing procedures in the Complete Maintenance section.