PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

NMP611 OP A, DISC AY, FW SERVICEValve,safety Relief

Emerson Automation Solutions Final Control Us Lp Div Navy Product Team · NSN 4820-01-538-2850 · FSC 4820 · No Item Name Available
Verified by PartsTable
NSN 4820-01-538-2850 — this item is cataloged by the U.S. Government under National Stock Number 4820-01-538-2850. Primary manufacturer part number: NMP611 OP A, DISC AY, FW SERVICE.
Features
  • Valve,safety Relief — FSC 4820
  • Connection Type: FLANGE ALL ENDS
  • Style Designator: ANGLE FLANGED ENDS
  • Second Connection Face to Centerline Distance: 5.500 INCHES IN
  • Bolt Circle Nominal Diameter: 6.062 INCHES ALL ENDS IN
  • Material: COPPER ALLOY STEM
  • Specification/standard Data: 81349 - MIL-V-20065C GOVERNMENT SPECIFICATION
  • Departure From Cited Document: RELIEF VALVE
Applications
  • Flow control in piping systems
  • Pressure regulation
  • Steam and fluid isolation
  • Applications requiring Copper Alloy Stem construction
General Description

The Valve,safety Relief, cataloged under National Stock Number 4820-01-538-2850, is classified within Federal Supply Class 4820 (No Item Name Available) of the Valves group. The primary manufacturer of record is Emerson Automation Solutions Final Control Us Lp Div Navy Product Team. Government technical data includes 28 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 4 commercial cross-references from 2 manufacturers, enabling identification through both NSN and commercial part number lookups. 2 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4820-01-538-2850
Primary Part NumberNMP611 OP A, DISC AY, FW SERVICE
Item NameValve,safety Relief
FSC / FSG4820 / 48 — No Item Name Available
ManufacturerEmerson Automation Solutions Final Control Us Lp Div Navy Product Team
StatusACTIVE
Connection TypeFLANGE ALL ENDS
Style DesignatorANGLE FLANGED ENDS
Second Connection Face to Centerline Distance5.500 INCHES IN
Bolt Circle Nominal Diameter6.062 INCHES ALL ENDS IN
MaterialCOPPER ALLOY STEM
Specification/standard Data81349 - MIL-V-20065C GOVERNMENT SPECIFICATION
Departure From Cited DocumentRELIEF VALVE
Flange Face DesignPLAIN ALL ENDS
Test Data DocumentMIL-S-901C SPECIFICATION (INCLUDES ENGINEERING TYPE BULLETINS, BROCHURES,ETC., THAT REFLECT SPECIFICATION TYPE DATA IN SPECIFICATION FORMAT; EXCLUDES COMMERCIAL CATALOGS, INDUSTRY DIRECTORIES, AND SIMILAR TRADE PUBLICATIONS, REFLECTING GENERAL TYPE DATA ON CERTAIN ENVIRONMENTAL AND PERFORMANCE REQUIREMENTS AND TEST CONDITIONS THAT ARE SHOWN AS "TYPICAL", "AVERAGE", "NOMINAL", ETC.).
First Connection Face to Centerline Distance7.250 INCHES IN
Nominal Outside Diameter7.188 INCHES ALL ENDS IN
Operating Pressure100.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS
Bolt Hole Nominal Diameter0.562 INCHES ALL ENDS IN
Media for Which DesignedWATER, FRESH SINGLE RESPONSE
Nominal Thickness0.500 INCHES ALL ENDS IN
Furnished Items and Quantity1 LEVER
Material Document and ClassificationQQ-B-637 COMP I FED SPEC SINGLE MATERIAL RESPONSE STEM
Flow Control DeviceDISK
Features ProvidedMANUAL OVERRIDE
MaterialNICKEL ALLOY SEAT
Valve Size3.500 INCHES IN
Bonnet Attachment MethodBOLTED
Adjustable Pressure Range+11.0 TO 17.0 POUNDS PER SQUARE INCH LBS
Material Document and ClassificationMIL-B-16541 MIL SPEC SINGLE MATERIAL RESPONSE FLOW CONTROL DEVICE
Flange ShapeROUND WITH HOLES ALL ENDS
Material Document and Classification11-N-268 FED SPEC SINGLE MATERIAL RESPONSE SEAT
Nondefinitive Spec/std DataA-1 TYPE AND C CLASS
Material Document and ClassificationMIL-B-16541 MIL SPEC SINGLE MATERIAL RESPONSE BODY
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 2
4820-01-533-90990041040038 INTERCHANGEABLE
Stem,fluid Valve
Emerson Automation Solutions Final Control Us Lp Div Navy Product Team
4820-01-538-2868012.500.0010 INTERCHANGEABLE
Seat,valve
Emerson Automation Solutions Final Control Us Lp Div Navy Product Team
Cross-Reference Index
Part NumberManufacturer
NMP611 OP A, DISC AY, FW SERVICE PRIMARY Emerson Automation Solutions Final Control Us Lp Div Navy Product Team (USA)
NMP611 Emerson Automation Solutions Final Control Us Lp Div Navy Product Team (USA)
MIL-V-20065 Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M
L-2210-C 3.5" 11TO17PSI Emerson Automation Solutions Final Control Us Lp Div Navy Product Team (USA)
Related Parts
4820-01-533-9099INTERCHANGEABLE
STEM,FLUID VALVE
0041040038
4820-01-538-2868INTERCHANGEABLE
SEAT,VALVE
012.500.0010

Frequently Asked Questions

What is NSN 4820-01-538-2850?

NSN 4820-01-538-2850 is a Valve,safety Relief, manufactured by Emerson Automation Solutions Final Control Us Lp Div Navy Product Team, classified under FSC 4820 (No Item Name Available). Status: active.

What are the part numbers for NSN 4820-01-538-2850?

NSN 4820-01-538-2850 has 4 cross-referenced part numbers: NMP611 OP A, DISC AY, FW SERVICE (Emerson Automation Solutions Final Control Us Lp Div Navy Product Team), NMP611 (Emerson Automation Solutions Final Control Us Lp Div Navy Product Team), MIL-V-20065 (Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M), L-2210-C 3.5" 11TO17PSI (Emerson Automation Solutions Final Control Us Lp Div Navy Product Team).

What NSN replaces 4820-01-538-2850?

There are 2 known substitutes for 4820-01-538-2850: 4820-01-533-9099, 4820-01-538-2868. Verify interchangeability with system specifications before substitution.

What are the specifications of NMP611 OP A, DISC AY, FW SERVICE?

Key specifications for NMP611 OP A, DISC AY, FW SERVICE: Connection Type: FLANGE ALL ENDS; Style Designator: ANGLE FLANGED ENDS; Second Connection Face to Centerline Distance: 5.500 INCHES IN; Bolt Circle Nominal Diameter: 6.062 INCHES ALL ENDS IN. 30 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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