PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

51558Valve,exhalation,respirator

Aearo Company · NSN 4240-01-251-3283 · FSC 4240 · No Item Name Available
Verified by PartsTable
NSN 4240-01-251-3283 — this item is cataloged by the U.S. Government under National Stock Number 4240-01-251-3283. Primary manufacturer part number: 51558.
Features
  • Valve,exhalation,respirator — FSC 4240
  • Criticality Code Justification: TEXT
  • General Characteristics Item Description: SOLE SOURCE REQUIRED BY STATUTE 6.302
  • 1 verified cross-reference
  • Primary manufacturer: Aearo Company
Applications
  • Flow control in piping systems
  • Pressure regulation
  • Steam and fluid isolation
General Description

The Valve,exhalation,respirator, cataloged under National Stock Number 4240-01-251-3283, is classified within Federal Supply Class 4240 (No Item Name Available) of the Fire Fighting, Rescue, and Safety Equipment group. The primary manufacturer of record is Aearo Company. Government technical data includes 2 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 1 commercial cross-reference from 1 manufacturer, enabling identification through both NSN and commercial part number lookups. 7 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4240-01-251-3283
Primary Part Number51558
Item NameValve,exhalation,respirator
FSC / FSG4240 / 42 — No Item Name Available
ManufacturerAearo Company
StatusACTIVE
Criticality Code JustificationTEXT
General Characteristics Item DescriptionSOLE SOURCE REQUIRED BY STATUTE 6.302
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 7
4320-00-132-4648 INTERCHANGEABLE
Ring,wearing
3040-00-356-3500SC-C-70650 INTERCHANGEABLE
Detent Plate
Us Army Communications & Electronics Materiel Readiness Command Logistics Engineering Dir
1680-00-511-544951558 INTERCHANGEABLE
Adapter,flexible Sh
Safran Electronics & Defense, Avionics Usa, Llc Dba Use CAGE Code 879b2 for Cataloging
5310-00-576-0900NAS620-3L INTERCHANGEABLE
Washer,flat
National Aerospace Standards Committee Aerospace Industries Association of America Inc Not for Rfq or Solicitation Use
4140-01-115-5976 INTERCHANGEABLE
Impeller,fan,axial
5998-01-135-1530 INTERCHANGEABLE
Printed Wiring Board
8345-01-590-1729 INTERCHANGEABLE
Flag,us Army Meddac
Cross-Reference Index
Part NumberManufacturer
51558 Aearo Company (USA)
Related Parts
4320-00-132-4648INTERCHANGEABLE
RING,WEARING
3040-00-356-3500INTERCHANGEABLE
DETENT PLATE
SC-C-70650
1680-00-511-5449INTERCHANGEABLE
ADAPTER,FLEXIBLE SH
51558
5310-00-576-0900INTERCHANGEABLE
WASHER,FLAT
NAS620-3L
4140-01-115-5976INTERCHANGEABLE
IMPELLER,FAN,AXIAL
5998-01-135-1530INTERCHANGEABLE
PRINTED WIRING BOARD
8345-01-590-1729INTERCHANGEABLE
FLAG,US ARMY MEDDAC

Frequently Asked Questions

What is NSN 4240-01-251-3283?

NSN 4240-01-251-3283 is a Valve,exhalation,respirator, manufactured by Aearo Company, classified under FSC 4240 (No Item Name Available). Status: active.

What are the part numbers for NSN 4240-01-251-3283?

NSN 4240-01-251-3283 has 1 cross-referenced part number: 51558 (Aearo Company).

What NSN replaces 4240-01-251-3283?

There are 7 known substitutes for 4240-01-251-3283: 4320-00-132-4648, 3040-00-356-3500, 1680-00-511-5449 and 4 more. Verify interchangeability with system specifications before substitution.

What are the specifications of 51558?

Key specifications for 51558: End Item Identification: AMERICAN OPTICAL MODEL 7 STAR SERIES 7700 AND 7800 RESPIRAOTR; Criticality Code Justification: TEXT; General Characteristics Item Description: SOLE SOURCE REQUIRED BY STATUTE 6.302. 3 total characteristics are documented in the Federal Logistics Information System.

Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
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