PartsTable
Technical Data Sheet
PartsTable / COMPONENT / 31721-FSOB-4
31721-FSOB-4 ✓ Verified by PartsTable
— · HOSE FITTING
WHAT YOU NEED TO KNOW
PTFE tape on tapered threads (NPT/BSPT) JIC/AN flare connections seal metal-to-metal — no tape
NPT != BSPT — look identical, NOT interchangeable
PRODUCT OVERVIEW

The RESTRICTOR,FLUID FLOW is a the manufacturer industrial component. Key specifications include length: 0.625 INCHES NOMINAL IN, material: COPPER ALLOY, design_type: TUBULAR, thread_class: 2A LOCATION NOT OTHERWISE SPECIFIED A, thread_series: UNF LOCATION NOT OTHERWISE SPECIFIED, orifice_diameter: 0.101 INCHES NOMINAL IN. This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 4730-01-387-7243, indicating validated use in U.S. government and defense logistics supply chains. Available through authorized enterprise resellers and TPM (Third Party Maintenance) channels.

Verify compatibility with your specific system configuration before ordering.

WHERE IT FITS
31721-FSOB-4
NSN: 4730-01-387-7243
FSC: 4730
CAGE: 22501 — HOWELL LABORATORIES INC DBA HOWELL LABORATORIES INC (USA)
SPECIFICATIONS
length0.625 INCHES NOMINAL IN
materialCOPPER ALLOY
design_typeTUBULAR
thread_class2A LOCATION NOT OTHERWISE SPECIFIED A
thread_seriesUNF LOCATION NOT OTHERWISE SPECIFIED
orifice_diameter0.101 INCHES NOMINAL IN
outside_diameter0.250 INCHES NOMINAL IN
special_featuresPURGE ORIFICE
thread_directionRIGHT-HAND LOCATION NOT OTHERWISE SPECIFIED
thread_provisionTHREADED LOCATION NOT OTHERWISE SPECIFIED
thread_size_designator7/16-20 LOCATION NOT OTHERWISE SPECIFIED
end_item_identificationDEHYDRATOR UNIT
NSN4730-01-387-7243
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: 31721-FSOB-4 · OEM ⚠ VERIFY BEFORE ORDERING NPT ≠ BSPT — tapered threads look identical but are NOT interchangeable. Wrong thread = leak. JIC (37°) ≠ AN (37°) ≠ SAE 45° — flare angles must match exactly. Measure thread pitch with gauge — visual identification is unreliable ✓ BROKER TIP Always use thread sealant (PTFE tape or pipe compound) on tapered threads (NPT/BSPT). JIC/AN flare fittings seal metal-to-metal — never use tape on flare connections PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
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
•
ORIFICE DIAMETER: 0.101 INCHES NOMINAL IN
TECHNICAL CHARACTERISTICS (FLIS)
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
END ITEM IDENTIFICATIONDEHYDRATOR UNIT
OUTSIDE DIAMETER0.250 INCHES NOMINAL IN
VERIFIED SUBSTITUTES & CROSS-REFERENCES 15
B5849Interchangeable
interchangeable cross-reference
interchangeable
5849Interchangeable
interchangeable cross-reference
interchangeable
6278Interchangeable
interchangeable cross-reference
interchangeable
5160240-00Interchangeable
interchangeable cross-reference
interchangeable
953Interchangeable
interchangeable cross-reference
interchangeable
395400Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
Ready to buy 31721-FSOB-4?
Compare prices from verified sellers on eBay
Buy on eBay →
As an eBay Partner, PartsTable may earn a commission. Your price is not affected.
FREQUENTLY ASKED QUESTIONS
What is 31721-FSOB-4?
31721-FSOB-4 is a RESTRICTOR,FLUID FLOW.
What parts can replace 31721-FSOB-4?
There are 15 known substitutes for 31721-FSOB-4: B5849, 5849, 6278 and 12 more. Substitute compatibility should be verified for your specific system.
What is the NSN for 31721-FSOB-4?
31721-FSOB-4 is cataloged in the Federal Logistics Information System (FLIS) under NSN 4730-01-387-7243. This indicates validated use in U.S. government and defense supply chains.
Community Feedback
Comments (0)
No comments yet. Be the first to share what you know.
Leave a Comment
Comments are reviewed before appearing. You will receive an email to verify before your comment appears.

Request a Quote — 31721-FSOB-4

✓ Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com
Last verified: July 2026