PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

31721-FSOB-4Restrictor,fluid Flow

Howell Laboratories Inc Dba Howell Laboratories Inc · NSN 4730-01-387-7243 · FSC 4730 · No Item Name Available
Verified by PartsTable
NSN 4730-01-387-7243 — this item is cataloged by the U.S. Government under National Stock Number 4730-01-387-7243. Primary manufacturer part number: 31721-FSOB-4.
Features
  • Restrictor,fluid Flow — FSC 4730
  • Thread Series: UNF LOCATION NOT OTHERWISE SPECIFIED
  • Thread Size Designator: 7/16-20 LOCATION NOT OTHERWISE SPECIFIED
  • Design Type: TUBULAR
  • Thread Class: 2A LOCATION NOT OTHERWISE SPECIFIED A
  • Thread Provision: THREADED LOCATION NOT OTHERWISE SPECIFIED
  • Thread Direction: RIGHT-HAND LOCATION NOT OTHERWISE SPECIFIED
  • Length: 0.625 INCHES NOMINAL IN
Applications
  • Applications requiring Copper Alloy construction
General Description

The Restrictor,fluid Flow, cataloged under National Stock Number 4730-01-387-7243, is classified within Federal Supply Class 4730 (No Item Name Available) of the Pipe, Tubing, Hose, and Fittings group. The primary manufacturer of record is Howell Laboratories Inc Dba Howell Laboratories Inc. Government technical data includes 10 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 3 commercial cross-references from 1 manufacturer, enabling identification through both NSN and commercial part number lookups. 8 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4730-01-387-7243
Primary Part Number31721-FSOB-4
Item NameRestrictor,fluid Flow
FSC / FSG4730 / 47 — No Item Name Available
ManufacturerHowell Laboratories Inc Dba Howell Laboratories Inc
StatusACTIVE
Thread SeriesUNF LOCATION NOT OTHERWISE SPECIFIED
Thread Size Designator7/16-20 LOCATION NOT OTHERWISE SPECIFIED
Design TypeTUBULAR
Thread Class2A LOCATION NOT OTHERWISE SPECIFIED A
Thread ProvisionTHREADED LOCATION NOT OTHERWISE SPECIFIED
Thread DirectionRIGHT-HAND LOCATION NOT OTHERWISE SPECIFIED
Length0.625 INCHES NOMINAL IN
Orifice Diameter0.101 INCHES NOMINAL IN
Outside Diameter0.250 INCHES NOMINAL IN
MaterialCOPPER ALLOY
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 8
4310-00-061-50675849 INTERCHANGEABLE
Ring,piston
Quincy Compressor Division of Coltec Industries Inc Dba Quincy Compressor Div Quincy Compressor
4930-00-141-825812Z8012-1 INTERCHANGEABLE
Adapter,grease Gun Coupling
Navair and Navsea Managed Original Design Activity Dwg Not Material/parts Supplier
5999-00-166-9771953 INTERCHANGEABLE
Contact Assembly,electrical
Anderson Airmotive Inc
3120-00-350-6461 INTERCHANGEABLE
Bushing
5950-00-538-2780 INTERCHANGEABLE
Transformer,power
5365-00-562-7114K 670 INTERCHANGEABLE
Ring,flinger
Waterous Company
5305-00-802-4689NAS584-9 INTERCHANGEABLE
Screw,close Tolerance
National Aerospace Standards Committee Aerospace Industries Association of America Inc Not for Rfq or Solicitation Use
6105-01-369-2418E9510 INTERCHANGEABLE
Motor,alternating Current
General Electric Co Motor Business Group
Cross-Reference Index
Part NumberManufacturer
5995 ITEM 4 Howell Laboratories Inc Dba Howell Laboratories Inc (USA)
5849 Howell Laboratories Inc Dba Howell Laboratories Inc (USA)
31721-FSOB-4 PRIMARY Howell Laboratories Inc Dba Howell Laboratories Inc (USA)
Related Parts
4310-00-061-5067INTERCHANGEABLE
RING,PISTON
5849
4930-00-141-8258INTERCHANGEABLE
ADAPTER,GREASE GUN COUPLING
12Z8012-1
5999-00-166-9771INTERCHANGEABLE
CONTACT ASSEMBLY,ELECTRICAL
953
3120-00-350-6461INTERCHANGEABLE
BUSHING
5950-00-538-2780INTERCHANGEABLE
TRANSFORMER,POWER
5365-00-562-7114INTERCHANGEABLE
RING,FLINGER
K 670
5305-00-802-4689INTERCHANGEABLE
SCREW,CLOSE TOLERANCE
NAS584-9
6105-01-369-2418INTERCHANGEABLE
MOTOR,ALTERNATING CURRENT
E9510

Frequently Asked Questions

What is NSN 4730-01-387-7243?

NSN 4730-01-387-7243 is a Restrictor,fluid Flow, manufactured by Howell Laboratories Inc Dba Howell Laboratories Inc, classified under FSC 4730 (No Item Name Available). Status: active.

What are the part numbers for NSN 4730-01-387-7243?

NSN 4730-01-387-7243 has 3 cross-referenced part numbers: 5995 ITEM 4 (Howell Laboratories Inc Dba Howell Laboratories Inc), 5849 (Howell Laboratories Inc Dba Howell Laboratories Inc), 31721-FSOB-4 (Howell Laboratories Inc Dba Howell Laboratories Inc).

What NSN replaces 4730-01-387-7243?

There are 8 known substitutes for 4730-01-387-7243: 4310-00-061-5067, 4930-00-141-8258, 5999-00-166-9771 and 5 more. Verify interchangeability with system specifications before substitution.

What are the specifications of 31721-FSOB-4?

Key specifications for 31721-FSOB-4: Thread Series: UNF LOCATION NOT OTHERWISE SPECIFIED; Thread Size Designator: 7/16-20 LOCATION NOT OTHERWISE SPECIFIED; Design Type: TUBULAR; Thread Class: 2A LOCATION NOT OTHERWISE SPECIFIED A. 12 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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