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PartsTable / COMPONENT / MS21937-4HC
MS21937-4HC ✓ 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 INJECTOR ASSEMBLY,FUEL is a the manufacturer industrial component. Key specifications include material: ALUMINUM ALLOY 2014, thread_size: 7/16IN-20 IN, thread_class: 3B, thread_length: 0.344 INCHES NOMINAL IN, overall_length: 0.500 INCHES NOMINAL IN, style_designator: HEXAGON, INTERNAL THREAD, SHOULDERED. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 4730-00-684-0564, 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
MS21937-4HC
NSN: 4730-00-684-0564
FSC: 4730
CAGE: 96906 — MILITARY STANDARDS PROMULGATED BY MILITARY DEPARTMENTS UNDER AUTHORITY OF DEFENSE STANDARDIZATION MANUAL 4120 3-M
SPECIFICATIONS
materialALUMINUM ALLOY 2014
thread_size7/16IN-20 IN
thread_class3B
thread_length0.344 INCHES NOMINAL IN
overall_length0.500 INCHES NOMINAL IN
style_designatorHEXAGON, INTERNAL THREAD, SHOULDERED
thread_directionRIGHT-HAND
surface_treatmentANODIZE
length_to_shoulder0.344 INCHES NOMINAL IN
width_across_flats1.000 INCHES NOMINAL IN
screw_thread_locationINTERNAL
casehardening_indicatorNOT CASEHARDENED
NSN4730-00-684-0564
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: MS21937-4HC · 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 SIZE: 7/16IN-20 IN
•
LARGEST INSIDE DIAMETER: 0.875 INCHES NOMINAL IN
•
SCREW THREAD SERIES DESIGNATOR: UNIFIED NATIONAL JOINT FINE (UNJF)
•
SCREW THREAD LOCATION: INTERNAL
•
MAJOR UNTHREADED OUTSIDE DIAMETER: 1.000 INCHES NOMINAL IN
•
WIDTH ACROSS FLATS: 1.000 INCHES NOMINAL IN
•
LENGTH TO SHOULDER: 0.344 INCHES NOMINAL IN
TECHNICAL CHARACTERISTICS (FLIS)
THREAD SIZE7/16IN-20 IN
OVERALL LENGTH0.500 INCHES NOMINAL IN
LARGEST INSIDE DIAMETER0.875 INCHES NOMINAL IN
SCREW THREAD SERIES DESIGNATORUNIFIED NATIONAL JOINT FINE (UNJF)
SCREW THREAD LOCATIONINTERNAL
MAJOR UNTHREADED OUTSIDE DIAMETER1.000 INCHES NOMINAL IN
WIDTH ACROSS FLATS1.000 INCHES NOMINAL IN
LENGTH TO SHOULDER0.344 INCHES NOMINAL IN
MATERIALALUMINUM ALLOY 2014
SURFACE TREATMENTANODIZE
VERIFIED SUBSTITUTES & CROSS-REFERENCES 12
133591Interchangeable
interchangeable cross-reference
interchangeable
B39A39Interchangeable
interchangeable cross-reference
interchangeable
AN818-4Interchangeable
interchangeable cross-reference
interchangeable
MS21937-5HInterchangeable
interchangeable cross-reference
interchangeable
AS18280Interchangeable
interchangeable cross-reference
interchangeable
105-01488Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusCANCELLED
Availability—
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is MS21937-4HC?
MS21937-4HC is a INJECTOR ASSEMBLY,FUEL.
What parts can replace MS21937-4HC?
There are 12 known substitutes for MS21937-4HC: 133591, B39A39, AN818-4 and 9 more. Substitute compatibility should be verified for your specific system.
Is MS21937-4HC still available?
MS21937-4HC is currently cancelled.
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✓ Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com
Last verified: July 2026