PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

16649-18Valve,safety Relief

Howden Fluid Systems · NSN 4820-00-342-4799 · FSC 4820 · No Item Name Available
Verified by PartsTable
NSN 4820-00-342-4799 — this item is cataloged by the U.S. Government under National Stock Number 4820-00-342-4799. Primary manufacturer part number: 16649-18.
Features
  • Valve,safety Relief — FSC 4820
  • Material: ALUMINUM ALLOY 2024 SEAT
  • Style Designator: STRAIGHT THRU
  • Maximum Operating Temp: -70.0 FAHRENHEIT FIRST RESPONSE DEGF
  • Maximum Operating Temp: 450.0 FAHRENHEIT SECOND RESPONSE DEGF
  • Connection Style: PLAIN (PIPE) FIRST END
  • Media for Which Designed: OXYGEN, GASEOUS SECOND RESPONSE
  • Nominal Thread Size: 0.125 INCHES FIRST END IN
Applications
  • Flow control in piping systems
  • Pressure regulation
  • Steam and fluid isolation
  • Applications requiring Aluminum Alloy 2024 Seat construction
General Description

The Valve,safety Relief, cataloged under National Stock Number 4820-00-342-4799, is classified within Federal Supply Class 4820 (No Item Name Available) of the Valves group. The primary manufacturer of record is Howden Fluid Systems. Government technical data includes 22 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 7 commercial cross-references from 3 manufacturers, enabling identification through both NSN and commercial part number lookups. 12 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4820-00-342-4799
Primary Part Number16649-18
Item NameValve,safety Relief
FSC / FSG4820 / 48 — No Item Name Available
ManufacturerHowden Fluid Systems
StatusACTIVE
MaterialALUMINUM ALLOY 2024 SEAT
Style DesignatorSTRAIGHT THRU
Maximum Operating Temp-70.0 FAHRENHEIT FIRST RESPONSE DEGF
Maximum Operating Temp450.0 FAHRENHEIT SECOND RESPONSE DEGF
Connection StylePLAIN (PIPE) FIRST END
Media for Which DesignedOXYGEN, GASEOUS SECOND RESPONSE
Nominal Thread Size0.125 INCHES FIRST END IN
MaterialALUMINUM ALLOY 2024 BODY
Thread Series DesignatorNPT FIRST END
Operating Pressure30.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM FIRST RESPONSE LBS
Thread DirectionRIGHT-HAND FIRST END
Disk Loading MethodSPRING
Media for Which DesignedAIR FIRST RESPONSE
Valve Discharge Flow Rate0.9 CUBIC FEET PER MINUTE
Media for Which DesignedOIL, CHLORINATED TRANSFORMER THIRD RESPONSE
Opening Pressure Setting26.0 POUNDS PER SQUARE INCH LBS
Surface TreatmentANODIZE LOCATION NOT OTHERWISE SPECIFIED
MaterialSTEEL CORROSION RESISTING AND SILICON FLOW CONTROL DEVICE
Connection TypeTHREADED EXTERNAL PIPE FIRST END
Valve Operation MethodAUTOMATIC
Flow Control DeviceDISK
MaterialALUMINUM ALLOY 2024 STEM
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 12
2910-00-030-3580 INTERCHANGEABLE
Parts Kit,carburetor
4730-00-050-4203AS15001-1 INTERCHANGEABLE
Fitting,lubrication
Sae International Dba Sae International
5310-00-139-6551 INTERCHANGEABLE
Washer,special
9540-00-175-3542 INTERCHANGEABLE
Angle,structural
1450-00-393-0023 INTERCHANGEABLE
Retainer
5330-00-423-6010 INTERCHANGEABLE
Gasket
5915-00-590-814353575 INTERCHANGEABLE
Filter,radio Frequency Interfere
Raytheon Company Dba Raytheon
5935-00-681-4757 INTERCHANGEABLE
Connector,plug,electrical
5136-00-729-5693 INTERCHANGEABLE
Tap,thread Cutting
6625-00-897-5163 INTERCHANGEABLE
Meter,audio Level
Cross-Reference Index
Part NumberManufacturer
16649-18 Howden Fluid Systems (USA)
14023 Meggitt (north Hollywood), Inc. Dba Meggitt Control Systems Div Meggitt Defense Systems, Inc. (USA)
16649 Meggitt (north Hollywood), Inc. Dba Meggitt Control Systems Div Meggitt Defense Systems, Inc. (USA)
16649 Howden Fluid Systems (USA)
16649-18 Meggitt (north Hollywood), Inc. Dba Meggitt Control Systems Div Meggitt Defense Systems, Inc. (USA)
14023 Howden Fluid Systems (USA)
7620119 Us Army Aviation and Missile Command (USA)
Related Parts
2910-00-030-3580INTERCHANGEABLE
PARTS KIT,CARBURETOR
4730-00-050-4203INTERCHANGEABLE
FITTING,LUBRICATION
AS15001-1
5310-00-139-6551INTERCHANGEABLE
WASHER,SPECIAL
9540-00-175-3542INTERCHANGEABLE
ANGLE,STRUCTURAL
1450-00-393-0023INTERCHANGEABLE
RETAINER
5330-00-423-6010INTERCHANGEABLE
GASKET
5915-00-590-8143INTERCHANGEABLE
FILTER,RADIO FREQUENCY INTERFERE
53575
5935-00-681-4757INTERCHANGEABLE
CONNECTOR,PLUG,ELECTRICAL
5136-00-729-5693INTERCHANGEABLE
TAP,THREAD CUTTING
6625-00-897-5163INTERCHANGEABLE
METER,AUDIO LEVEL
5962-01-142-7325INTERCHANGEABLE
MICROCIRCUIT,DIGITAL
6130-01-258-8742INTERCHANGEABLE
POWER SUPPLY

Frequently Asked Questions

What is NSN 4820-00-342-4799?

NSN 4820-00-342-4799 is a Valve,safety Relief, manufactured by Howden Fluid Systems, classified under FSC 4820 (No Item Name Available). Status: active.

What are the part numbers for NSN 4820-00-342-4799?

NSN 4820-00-342-4799 has 7 cross-referenced part numbers: 16649-18 (Howden Fluid Systems), 14023 (Meggitt (north Hollywood), Inc. Dba Meggitt Control Systems Div Meggitt Defense Systems, Inc.), 16649 (Meggitt (north Hollywood), Inc. Dba Meggitt Control Systems Div Meggitt Defense Systems, Inc.), 16649 (Howden Fluid Systems), 16649-18 (Meggitt (north Hollywood), Inc. Dba Meggitt Control Systems Div Meggitt Defense Systems, Inc.) and 2 more.

What NSN replaces 4820-00-342-4799?

There are 12 known substitutes for 4820-00-342-4799: 2910-00-030-3580, 4730-00-050-4203, 5310-00-139-6551 and 9 more. Verify interchangeability with system specifications before substitution.

What are the specifications of 16649-18?

Key specifications for 16649-18: Material: ALUMINUM ALLOY 2024 SEAT; Style Designator: STRAIGHT THRU; Maximum Operating Temp: -70.0 FAHRENHEIT FIRST RESPONSE DEGF; Maximum Operating Temp: 450.0 FAHRENHEIT SECOND RESPONSE DEGF. 22 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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