PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

203355Seat,valve

Valcor Engineering Corporation · NSN 4820-00-303-6450 · FSC 4820 · No Item Name Available
Verified by PartsTable
NSN 4820-00-303-6450 — this item is cataloged by the U.S. Government under National Stock Number 4820-00-303-6450. Primary manufacturer part number: 203355.
Features
  • Seat,valve — FSC 4820
  • Under Flange Height: 0.187 INCHES NOMINAL IN
  • Flange Seat to Disk End Height: 0.125 INCHES NOMINAL IN
  • Seating Surface Shape: FLAT
  • Material Document and Classification: MIL-P-17091,TYPE F-10001 MIL SPEC SINGLE MATERIAL RESPONSE OVERALL
  • Style Designator: PLAIN FLANGED
  • Material: PLASTIC OVERALL
  • Flange Diameter: 0.500 INCHES NOMINAL IN
Applications
  • Flow control in piping systems
  • Pressure regulation
  • Steam and fluid isolation
  • Applications requiring Plastic Overall construction
General Description

The Seat,valve, cataloged under National Stock Number 4820-00-303-6450, is classified within Federal Supply Class 4820 (No Item Name Available) of the Valves group. The primary manufacturer of record is Valcor Engineering Corporation. Government technical data includes 8 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 2 commercial cross-references from 2 manufacturers, enabling identification through both NSN and commercial part number lookups. 4 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4820-00-303-6450
Primary Part Number203355
Item NameSeat,valve
FSC / FSG4820 / 48 — No Item Name Available
ManufacturerValcor Engineering Corporation
StatusACTIVE
Under Flange Height0.187 INCHES NOMINAL IN
Flange Seat to Disk End Height0.125 INCHES NOMINAL IN
Seating Surface ShapeFLAT
Material Document and ClassificationMIL-P-17091,TYPE F-10001 MIL SPEC SINGLE MATERIAL RESPONSE OVERALL
Style DesignatorPLAIN FLANGED
MaterialPLASTIC OVERALL
Flange Diameter0.500 INCHES NOMINAL IN
Body Inside Diameter0.250 INCHES NOMINAL IN
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 4
2520-00-164-4067203355 INTERCHANGEABLE
Countershaft,transm
Clark Material Handling Company
4920-00-801-8729203355 INTERCHANGEABLE
Fixture,aircraft Maintenance
Eaton Corp Dba Eaton Aerospace Jackson
5340-01-212-8311203355 INTERCHANGEABLE
Plunger,detent
Cummins Inc.
6145-01-531-6753 INTERCHANGEABLE
Cable,special Purpose,electrical
Cross-Reference Index
Part NumberManufacturer
203355 PRIMARY Valcor Engineering Corporation (USA)
203355 Kidde-Fenwal, Llc (USA)
Related Parts
2520-00-164-4067INTERCHANGEABLE
COUNTERSHAFT,TRANSM
203355
4920-00-801-8729INTERCHANGEABLE
FIXTURE,AIRCRAFT MAINTENANCE
203355
5340-01-212-8311INTERCHANGEABLE
PLUNGER,DETENT
203355
6145-01-531-6753INTERCHANGEABLE
CABLE,SPECIAL PURPOSE,ELECTRICAL

Frequently Asked Questions

What is NSN 4820-00-303-6450?

NSN 4820-00-303-6450 is a Seat,valve, manufactured by Valcor Engineering Corporation, classified under FSC 4820 (No Item Name Available). Status: active.

What are the part numbers for NSN 4820-00-303-6450?

NSN 4820-00-303-6450 has 2 cross-referenced part numbers: 203355 (Valcor Engineering Corporation), 203355 (Kidde-Fenwal, Llc).

What NSN replaces 4820-00-303-6450?

There are 4 known substitutes for 4820-00-303-6450: 2520-00-164-4067, 4920-00-801-8729, 5340-01-212-8311 and 1 more. Verify interchangeability with system specifications before substitution.

What are the specifications of 203355?

Key specifications for 203355: Under Flange Height: 0.187 INCHES NOMINAL IN; Flange Seat to Disk End Height: 0.125 INCHES NOMINAL IN; Seating Surface Shape: FLAT; Material Document and Classification: MIL-P-17091,TYPE F-10001 MIL SPEC SINGLE MATERIAL RESPONSE OVERALL. 8 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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