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MS21937-4L — Technical Data Sheet

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— · 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 7075, thread_size: 7/16IN-20 IN, thread_class: 3B, thread_length: 0.250 INCHES NOMINAL IN, overall_length: 0.406 INCHES NOMINAL IN, style_designator: HEXAGON, INTERNAL THREAD, SHOULDERED. This part is cataloged in the Federal Logistics Information System under NSN 4730-00-821-0189, 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
MS21937-4L
NSN: 4730-00-821-0189
FSC: 4730
CAGE: 17439 — CHICAGO PNEUMATIC TOOL CO (USA)
SPECIFICATIONS
materialALUMINUM ALLOY 7075
thread_size7/16IN-20 IN
thread_class3B
thread_length0.250 INCHES NOMINAL IN
overall_length0.406 INCHES NOMINAL IN
style_designatorHEXAGON, INTERNAL THREAD, SHOULDERED
thread_directionRIGHT-HAND
length_to_shoulder0.344 INCHES NOMINAL IN
width_across_flats1.000 INCHES NOMINAL IN
screw_thread_locationINTERNAL
casehardening_indicatorNOT CASEHARDENED
largest_inside_diameter0.562 INCHES NOMINAL IN
NSN4730-00-821-0189
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: MS21937-4L · 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 DIRECTION: RIGHT-HAND
•
SCREW THREAD LOCATION: INTERNAL
•
SPECIFICATION/STANDARD DATA: 81343-SAE AS21937 MANUFACTURERS STANDARD
•
WIDTH ACROSS FLATS: 1.000 INCHES NOMINAL IN
•
MAJOR UNTHREADED OUTSIDE DIAMETER: 0.687 INCHES NOMINAL IN
•
STYLE DESIGNATOR: HEXAGON, INTERNAL THREAD, SHOULDERED
•
LENGTH TO SHOULDER: 0.344 INCHES NOMINAL IN
•
MATERIAL: ALUMINUM ALLOY 7075
TECHNICAL CHARACTERISTICS
THREAD DIRECTIONRIGHT-HAND
SCREW THREAD LOCATIONINTERNAL
SPECIFICATION/STANDARD DATA81343-SAE AS21937 MANUFACTURERS STANDARD
WIDTH ACROSS FLATS1.000 INCHES NOMINAL IN
MAJOR UNTHREADED OUTSIDE DIAMETER0.687 INCHES NOMINAL IN
STYLE DESIGNATORHEXAGON, INTERNAL THREAD, SHOULDERED
LENGTH TO SHOULDER0.344 INCHES NOMINAL IN
MATERIALALUMINUM ALLOY 7075
THREAD LENGTH0.250 INCHES NOMINAL IN
SCREW THREAD SERIES DESIGNATORUNF
VERIFIED SUBSTITUTES & CROSS-REFERENCES 8
MS21937-5HInterchangeableGOVERNMENT REGISTRY
interchangeable cross-reference
interchangeable
AS18280InterchangeableGOVERNMENT REGISTRY
interchangeable cross-reference
interchangeable
105-01488InterchangeableGOVERNMENT REGISTRY
interchangeable cross-reference
interchangeable
MS21937W8HInterchangeableGOVERNMENT REGISTRY
interchangeable cross-reference
interchangeable
MS21937-4HInterchangeableGOVERNMENT REGISTRY
interchangeable cross-reference
interchangeable
MS21937-4HCInterchangeableGOVERNMENT REGISTRY
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusCANCELLEDGOVERNMENT REGISTRY
Availability—
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is MS21937-4L?
MS21937-4L is a INJECTOR ASSEMBLY,FUEL.
What parts can replace MS21937-4L?
There are 8 known substitutes for MS21937-4L: MS21937-5H, AS18280, 105-01488 and 5 more. Substitute compatibility should be verified for your specific system.
Is MS21937-4L still available?
MS21937-4L 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: October 2026