The Terminal,ventilation Duct, cataloged under National Stock Number 4520-00-396-1691, is classified within Federal Supply Class 4520 (Space and Water Heating Equipment) of the Plumbing, Heating, and Waste Disposal group. Government technical data includes 4 specifications, cited from the U.S. Government catalog. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 3 items share a part number with this NSN in the catalog (possible match — not a government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: Active.
| Parameter | Value |
|---|---|
| NSN | 4520-00-396-1691 |
| Item Name | Terminal,ventilation Duct |
| FSC / FSG | 4520 / 45 — Space and Water Heating Equipment |
| Status | ACTIVE |
| Overall Diameter | 13.500 INCHES NOMINAL IN |
| Style Designator | STRAIGHT |
| Damper | INCLUDED |
| Material | ALUMINUM |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Reference | Meaning |
|---|---|
| S3801-690702SIZE6 | 3/2 Design control — primary reference U.S. Government activity |
| S3801-690702 | D/9 Drawing number reference only U.S. Government activity |
| MIL-T-22576 | 5/9 Secondary reference U.S. Government activity |
NSN 4520-00-396-1691 is a Terminal,ventilation Duct, classified under FSC 4520, Space and Water Heating Equipment. Status: active.
3 possible matches (shared part number, not a government interchangeability claim): 4520-00-396-1693, 4520-00-396-1695, 4520-00-396-1696. Verify interchangeability with system specifications before substitution.
Key specifications for 4520-00-396-1691: Overall Diameter: 13.500 INCHES NOMINAL IN; Style Designator: STRAIGHT; Overall Length: 7.125 INCHES NOMINAL IN; Damper: INCLUDED. 4 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.