The Heater,duct Type,stationary, cataloged under National Stock Number 4520-01-191-3973, is classified within Federal Supply Class 4520 (Space and Water Heating Equipment) of the Plumbing, Heating, and Waste Disposal group. Government technical data includes 14 specifications, cited from the U.S. Government catalog. 8 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 3 items share a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Cancelled.
| Parameter | Value |
|---|---|
| NSN | 4520-01-191-3973 |
| Item Name | Heater,duct Type,stationary |
| FSC / FSG | 4520 / 45 — Space and Water Heating Equipment |
| Status | CANCELLED |
| Heat Delivery Rate | 10236.0 BRITISH THERMAL UNIT |
| Phase | THREE |
| Frequency in Hertz | 60.0 |
| Current Type | AC |
| Heat Medium Type | AIR |
| Inclosure Material | STEEL CORROSION RESISTING |
| Voltage in Volts | 440.0 |
| Nondefinitive Spec/std Data | 23EH SIZE AND M TYPE |
| Height | 6.250 INCHES NOMINAL IN |
| Depth | 6.000 INCHES NOMINAL IN |
| Width | 20.000 INCHES NOMINAL IN |
| Mounting Type | VENTILATION DUCT |
| Heating Element Type | ELECTRIC NONIMMERSION |
| Current Rating in Amps | 6.8 |
| Acquisition Status | CANCELLED |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Reference | Meaning |
|---|---|
| M22594-23M | 2/2 Government specification standardization U.S. Government activity |
| EH23M | 5/1 Secondary reference Valad Electric Heating Corp. |
| 106-056816-000 | D/9 Drawing number reference only Chromalox Inc Dba Chromalox Precision Heat and Control, Inc |
| 106-056816-011 | 5/1 Secondary reference Chromalox Inc Dba Chromalox Precision Heat and Control, Inc |
| MIL-H-22594 | 5/9 Secondary reference U.S. Government activity |
| 83-0808 | 5/1 Secondary reference Valad Electric Heating Corp. |
| TFZ-23M | 5/1 Secondary reference Indeeco Llc Dba Indeeco |
| MIL-PRF-22594 | 4/1 Identification reference U.S. Government activity |
NSN 4520-01-191-3973 is a Heater,duct Type,stationary, classified under FSC 4520, Space and Water Heating Equipment. Status: cancelled.
3 possible matches (shared part number, not a government interchangeability claim): 4520-01-192-1442, 4520-01-195-4315, 4520-01-200-0680. Verify interchangeability with system specifications before substitution.
Key specifications for 4520-01-191-3973: Heat Delivery Rate: 10236.0 BRITISH THERMAL UNIT; Phase: THREE; Frequency in Hertz: 60.0; Current Type: AC. 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.
NSN 4520-01-191-3973 is currently cancelled. Check with the Defense Logistics Agency for current availability and authorized substitutes.
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.