NSN 4820-01-491-9278 — this item is cataloged by the U.S. Government under National Stock Number 4820-01-491-9278. Manufacturer of record part number: 566-6985426-41.
The Valve,vent, cataloged under National Stock Number 4820-01-491-9278, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Naval Sea Systems Command. The record lists 1 manufacturer part number for this item, enabling identification through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 5 items share a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
Technical Specifications
Parameter
Value
NSN
4820-01-491-9278
Primary Part Number
566-6985426-41
Item Name
Valve,vent
FSC / FSG
4820 / 48 — Valves, Nonpowered
Manufacturer
Naval Sea Systems Command
Status
ACTIVE
Lifecycle & Compliance
Acquisition Status
ACTIVE
DEMIL Code
DEMIL A — No Demilitarization Required
Hazard
No hazard code in the DLA record (HMIC N)
Criticality Code
X
⇄Related Items5
Each row states its source: a government interchangeability/replacement code, or a possible match on a shared part number.
3120-01-492-418627RD00998112-016POSSIBLE MATCH
BUSHING,SLEEVE
Possible match (shared part number)Greene Tweed & Co Inc
3040-01-492-5513566-6985426-75POSSIBLE MATCH
RING,ROD,PISTON
Possible match (shared part number)Naval Sea Systems Command
5306-01-654-8009H621-0102-20POSSIBLE MATCH
BOLT,MACHINE
Possible match (shared part number)Electric Boat Corporation Div General Dynamics Electric Boat
5340-01-671-4938566-6985426 PC 12 BLANKPOSSIBLE MATCH
PLATE,MOUNTING
Possible match (shared part number)Naval Sea Systems Command
5310-01-673-7434566-6985426-11POSSIBLE MATCH
NUT,PLAIN,EXTENDED WASHER,HEXAGO
Possible match (shared part number)Naval Sea Systems Command
NSN 4820-01-491-9278 is a Valve,vent, manufactured by Naval Sea Systems Command, classified under FSC 4820, Valves, Nonpowered. Status: active.
What part numbers are listed for NSN 4820-01-491-9278?
NSN 4820-01-491-9278 has 1 manufacturer part number on file: 566-6985426-41 (Naval Sea Systems Command).
What NSN replaces 4820-01-491-9278?
5 possible matches (shared part number, not a government interchangeability claim): 3120-01-492-4186, 3040-01-492-5513, 5306-01-654-8009. Verify interchangeability with system specifications before substitution.
What are the specifications of 566-6985426-41?
Key specifications for 566-6985426-41: Special Features: NHA DESURGER ASSY, LENGTH 2.000 INCHES IN; End Item Identification: LOS ANGELES CLASS SSN (688). 0 specifications are documented in the U.S. Government catalog.
Is NSN 4820-01-491-9278 hazardous material?
No hazard code in the DLA record (HMIC N). Hazard information on this page is shown exactly as it appears in the DLA record.
Sources
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.
✓ Data cited from the U.S. Government catalog; commercial cross-references from OEM and certified industry sources.