PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

1771Valve,safety Relief

Lunkenheimer Co · NSN 4820-00-956-6181 · FSC 4820 · No Item Name Available
Verified by PartsTable
NSN 4820-00-956-6181 — this item is cataloged by the U.S. Government under National Stock Number 4820-00-956-6181. Primary manufacturer part number: 1771.
Features
  • Valve,safety Relief — FSC 4820
  • Bonnet Attachment Method: INTEGRAL
  • Nominal Pipe Size Accommodated: 1.500 INCHES SECOND END IN
  • Connection Style: PLAIN,OPTIONAL END(PIPE) FIRST END
  • Connection Type: THREADED INTERNAL PIPE FIRST END
  • Thread Series Designator: NPT FIRST END
  • Nominal Pipe Size Accommodated: 2.000 INCHES FIRST END IN
  • Thread Quantity Per Inch: 11-1/2 SECOND END
Applications
  • Flow control in piping systems
  • Pressure regulation
  • Steam and fluid isolation
  • Applications requiring Copper Alloy Overall construction
General Description

The Valve,safety Relief, cataloged under National Stock Number 4820-00-956-6181, is classified within Federal Supply Class 4820 (No Item Name Available) of the Valves group. The primary manufacturer of record is Lunkenheimer Co. Government technical data includes 23 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 1 commercial cross-reference from 1 manufacturer, enabling identification through both NSN and commercial part number lookups. 10 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4820-00-956-6181
Primary Part Number1771
Item NameValve,safety Relief
FSC / FSG4820 / 48 — No Item Name Available
ManufacturerLunkenheimer Co
StatusACTIVE
Bonnet Attachment MethodINTEGRAL
Nominal Pipe Size Accommodated1.500 INCHES SECOND END IN
Connection StylePLAIN,OPTIONAL END(PIPE) FIRST END
Connection TypeTHREADED INTERNAL PIPE FIRST END
Thread Series DesignatorNPT FIRST END
Nominal Pipe Size Accommodated2.000 INCHES FIRST END IN
Thread Quantity Per Inch11-1/2 SECOND END
Thread DirectionRIGHT-HAND SECOND END
Disk Loading MethodSPRING
Connection TypeTHREADED INTERNAL PIPE SECOND END
Thread Quantity Per Inch11-1/2 FIRST END
Nominal Thread Size1.500 INCHES SECOND END IN
Bonnet TypeINSIDE SPRING
Features ProvidedBONNET PACKING AND PRESSURE TIGHT OUTLET SIDE
Thread Series DesignatorNPT SECOND END
Thread DirectionRIGHT-HAND FIRST END
Flow Control DeviceDISK
Connection StylePLAIN,OPTIONAL END(PIPE) SECOND END
Opening Pressure Setting750.0 POUNDS PER SQUARE INCH LBS
Operating Pressure1300.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS
MaterialCOPPER ALLOY OVERALL
Nominal Thread Size2.000 INCHES FIRST END IN
Style DesignatorANGLE
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 10
5905-00-045-9389217063P69 INTERCHANGEABLE
Resistor,fixed,wire Wound
Bae Systems Information and Electronic Systems Integration Inc. Dba Bae Systems
4410-00-192-08751771 INTERCHANGEABLE
Nozzle Assembly
Hago Products Co
4730-00-273-949731168-006-14000 INTERCHANGEABLE
Packing Nut
The Gorman-Rupp Company Div Gorman-Rupp
2530-00-353-0408220353 INTERCHANGEABLE
Valve,relay,air Pressure
Crane Co Div Valve Div
8040-00-522-4312 INTERCHANGEABLE
Adhesive
4820-00-684-98331771 INTERCHANGEABLE
Valve,safety Relief
Eastern Co the Ccl Security Products
6625-00-708-99084000C14 INTERCHANGEABLE
Ammeter
Faria Beede Instruments, Inc. Dba Faria Beede Instruments Inc
4010-00-958-0637 INTERCHANGEABLE
Chain,weldless
5360-01-234-43691771 INTERCHANGEABLE
Spring,helical,compression
Matthew Warren, Inc. Dba Century Spring Corp. Div Century Spring Corp.
4820-01-416-16441771 INTERCHANGEABLE
Ball,check
Droitcour Co
Cross-Reference Index
Part NumberManufacturer
1771 Lunkenheimer Co (USA)
Related Parts
5905-00-045-9389INTERCHANGEABLE
RESISTOR,FIXED,WIRE WOUND
217063P69
4410-00-192-0875INTERCHANGEABLE
NOZZLE ASSEMBLY
1771
4730-00-273-9497INTERCHANGEABLE
PACKING NUT
31168-006-14000
2530-00-353-0408INTERCHANGEABLE
VALVE,RELAY,AIR PRESSURE
220353
8040-00-522-4312INTERCHANGEABLE
ADHESIVE
4820-00-684-9833INTERCHANGEABLE
VALVE,SAFETY RELIEF
1771
6625-00-708-9908INTERCHANGEABLE
AMMETER
4000C14
4010-00-958-0637INTERCHANGEABLE
CHAIN,WELDLESS
5360-01-234-4369INTERCHANGEABLE
SPRING,HELICAL,COMPRESSION
1771
4820-01-416-1644INTERCHANGEABLE
BALL,CHECK
1771

Frequently Asked Questions

What is NSN 4820-00-956-6181?

NSN 4820-00-956-6181 is a Valve,safety Relief, manufactured by Lunkenheimer Co, classified under FSC 4820 (No Item Name Available). Status: active.

What are the part numbers for NSN 4820-00-956-6181?

NSN 4820-00-956-6181 has 1 cross-referenced part number: 1771 (Lunkenheimer Co).

What NSN replaces 4820-00-956-6181?

There are 10 known substitutes for 4820-00-956-6181: 5905-00-045-9389, 4410-00-192-0875, 4730-00-273-9497 and 7 more. Verify interchangeability with system specifications before substitution.

What are the specifications of 1771?

Key specifications for 1771: Bonnet Attachment Method: INTEGRAL; Nominal Pipe Size Accommodated: 1.500 INCHES SECOND END IN; Connection Style: PLAIN,OPTIONAL END(PIPE) FIRST END; Connection Type: THREADED INTERNAL PIPE FIRST END. 23 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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