The Heater,water,gas, cataloged under National Stock Number 4520-00-552-3717, is classified within Federal Supply Class 4520 (Space and Water Heating Equipment) of the Plumbing, Heating, and Waste Disposal group. The manufacturer of record is Smith a O Water Products Co Div of a O Smith Corp. Government technical data includes 14 specifications, cited from the U.S. Government catalog. The record lists 1 manufacturer part number for this item, enabling identification through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. 1 item shares a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4520-00-552-3717 |
| Primary Part Number | FSG-40 |
| Item Name | Heater,water,gas |
| FSC / FSG | 4520 / 45 — Space and Water Heating Equipment |
| Manufacturer | Smith a O Water Products Co Div of a O Smith Corp |
| Status | ACTIVE |
| Water Outlet Connection Quantity | 2 |
| Overall Diameter | 18.250 INCHES NOMINAL IN |
| Capacity | 40.0 GALLONS TANK |
| Mounting Position | VERTICAL |
| Heating Capacity Per Hour | 37.7 GALLONS |
| Water Inlet Connection Quantity | 1 |
| Insulated Feature | INCLUDED |
| Operating Control Method | AUTOMATIC |
| Gas for Which Designed | NATURAL GAS |
| Temp Rise Per Hour | 90.0 FAHRENHEIT DEGF |
| Gas Connection Quantity | 1 |
| Surface Treatment | GLASS FIBER INSIDE |
| Surface Treatment | PAINT OUTSIDE |
| Material | STEEL |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Part Number | Manufacturer |
|---|---|
| FSG-40 PRIMARY | Smith a O Water Products Co Div of a O Smith Corp (USA) |
| Reference | Meaning |
|---|---|
| KGA40800 | 5/9 Secondary reference Smith a O Water Products Co Div of a O Smith Corp |
NSN 4520-00-552-3717 is a Heater,water,gas, manufactured by Smith a O Water Products Co Div of a O Smith Corp, classified under FSC 4520, Space and Water Heating Equipment. Status: active.
NSN 4520-00-552-3717 has 1 manufacturer part number on file: FSG-40 (Smith a O Water Products Co Div of a O Smith Corp).
1 possible match (shared part number, not a government interchangeability claim): 5330-01-314-4813. Verify interchangeability with system specifications before substitution.
Key specifications for FSG-40: Overall Height: 57.625 INCHES NOMINAL IN; Water Outlet Connection Quantity: 2; Overall Diameter: 18.250 INCHES NOMINAL IN; Capacity: 40.0 GALLONS TANK. 14 specifications are documented in the U.S. Government catalog.
No hazard code in the DLA record (HMIC N). Hazard information on this page is shown exactly as it appears in the DLA record.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-16.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.