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20521 ✓ Verified by PartsTable
Legrand · 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 RELAY,ELECTROMAGNETIC is a Legrand industrial component. Key specifications include width: 4.000 INCHES NOMINAL IN, height: 4.000 INCHES NOMINAL IN, length: 1.000 INCHES NOMINAL IN, material: ALUMINUM ALLOY, body_type: SOLID, duty_type: CONTINUOUS. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 4730-00-277-5309, 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
20521
NSN: 4730-00-277-5309
FSC: 4730
CAGE: 72759 — UNITED CATALYSTS INC (USA)
SPECIFICATIONS
width4.000 INCHES NOMINAL IN
height4.000 INCHES NOMINAL IN
length1.000 INCHES NOMINAL IN
materialALUMINUM ALLOY
body_typeSOLID
duty_typeCONTINUOUS
head_typeSOLID
time_delay30.00 SECONDS NOMINAL FIXED OPERATE TIME
design_typeSOLID
constructionSEAMLESS
end_diameter1.7150 INCHES NOMINAL IN
bore_diameter1.6250 INCHES NOMINAL IN
NSN4730-00-277-5309
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: 20521 · Legrand ⚠ 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
•
BODY TYPE: SOLID
•
DRIVE END STYLE: RAISED SQUARE
•
THREAD SERIES DESIGNATOR: NPT EXTERNAL
•
NOMINAL PIPE SIZE FOR WHICH DESIGNED: 0.125 INCHES IN
•
THREAD DIRECTION: RIGHT-HAND EXTERNAL
•
MATERIAL: STEEL CORROSION RESISTING OVERALL
•
NOMINAL THREAD SIZE: 0.125 INCHES EXTERNAL IN
•
CONNECTION STYLE: PLAIN
TECHNICAL CHARACTERISTICS (FLIS)
BODY TYPESOLID
DRIVE END STYLERAISED SQUARE
THREAD SERIES DESIGNATORNPT EXTERNAL
NOMINAL PIPE SIZE FOR WHICH DESIGNED0.125 INCHES IN
THREAD DIRECTIONRIGHT-HAND EXTERNAL
MATERIALSTEEL CORROSION RESISTING OVERALL
NOMINAL THREAD SIZE0.125 INCHES EXTERNAL IN
CONNECTION STYLEPLAIN
HEAD TYPESOLID
VERIFIED SUBSTITUTES & CROSS-REFERENCES 11
20521Interchangeable
interchangeable cross-reference
interchangeable
C3234-020-16Interchangeable
interchangeable cross-reference
interchangeable
13217E4066-1Interchangeable
interchangeable cross-reference
interchangeable
20714Interchangeable
interchangeable cross-reference
interchangeable
06-08906Interchangeable
Same NIIN cross-reference
interchangeable
272-1050P1Interchangeable
Same NIIN cross-reference
interchangeable
LIFECYCLE
StatusCANCELLED
Availability—
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is 20521?
20521 is a RELAY,ELECTROMAGNETIC manufactured by Legrand.
What parts can replace 20521?
There are 11 known substitutes for 20521: 20521, C3234-020-16, 13217E4066-1 and 8 more. Substitute compatibility should be verified for your specific system.
Is 20521 still available?
20521 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