PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

203921BThermostat,flow Control

Brinkley Technology Group Llc Dba Hercules Manufacturing · NSN 6685-00-527-6545 · FSC 6685 · No Item Name Available
Verified by PartsTable
NSN 6685-00-527-6545 — this item is cataloged by the U.S. Government under National Stock Number 6685-00-527-6545. Primary manufacturer part number: 203921B.
Features
  • Thermostat,flow Control — FSC 6685
  • Operating Temp Rating: 106.0 FAHRENHEIT NOMINAL DEGF
  • Flow Control Device: CHOKE
  • Inside Mounting Surface to Valve Seat Distance: 2.120 INCHES IN
  • Thread Size and Series/type Designator: 1-1/2-18 UNEF
  • Usage Design: COOL WATER
  • Spring Operated Pressure Relief: PROVIDED
  • Mounting Method: THREADED
Applications
  • Industrial maintenance and repair
  • Government and military logistics
  • Equipment overhaul and refurbishment
General Description

The Thermostat,flow Control, cataloged under National Stock Number 6685-00-527-6545, is classified within Federal Supply Class 6685 (No Item Name Available) of the Instruments and Laboratory Equipment group. The primary manufacturer of record is Brinkley Technology Group Llc Dba Hercules Manufacturing. Government technical data includes 15 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 5 commercial cross-references from 3 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
NSN6685-00-527-6545
Primary Part Number203921B
Item NameThermostat,flow Control
FSC / FSG6685 / 66 — No Item Name Available
ManufacturerBrinkley Technology Group Llc Dba Hercules Manufacturing
StatusACTIVE
Operating Temp Rating106.0 FAHRENHEIT NOMINAL DEGF
Flow Control DeviceCHOKE
Inside Mounting Surface to Valve Seat Distance2.120 INCHES IN
Thread Size and Series/type Designator1-1/2-18 UNEF
Usage DesignCOOL WATER
Spring Operated Pressure ReliefPROVIDED
Mounting MethodTHREADED
Accessory Components and QuantityGASKET,MTG
Closing Pressure Setting39.0 POUNDS PER SQUARE INCH NOMINAL LBS
Opening Temp Rating99.0 FAHRENHEIT NOMINAL DEGF
Distance Across Flats1.750 INCHES NOMINAL IN
Thread DirectionRIGHT-HAND
Opening Pressure SettingERR-060
Valve Travel Distance0.197 INCHES NOMINAL IN
Thermostat TypeBELLOWS
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 2
4730-00-530-72967235160 INTERCHANGEABLE
Strainer Element,sediment
Kalmar AC Inc
2815-01-297-91133910811 INTERCHANGEABLE
Rocker Arm,engine Poppet Valve
Cummins Inc.
Cross-Reference Index
Part NumberManufacturer
203921B Hercules Engine Co Inc (USA)
208135 Brinkley Technology Group Llc Dba Hercules Manufacturing (USA)
XTA25000-19 Scovill Inc (USA)
203921B PRIMARY Brinkley Technology Group Llc Dba Hercules Manufacturing (USA)
208135 Hercules Engine Co Inc (USA)
Related Parts
4730-00-530-7296INTERCHANGEABLE
STRAINER ELEMENT,SEDIMENT
7235160
2815-01-297-9113INTERCHANGEABLE
ROCKER ARM,ENGINE POPPET VALVE
3910811

Frequently Asked Questions

What is NSN 6685-00-527-6545?

NSN 6685-00-527-6545 is a Thermostat,flow Control, manufactured by Brinkley Technology Group Llc Dba Hercules Manufacturing, classified under FSC 6685 (No Item Name Available). Status: active.

What are the part numbers for NSN 6685-00-527-6545?

NSN 6685-00-527-6545 has 5 cross-referenced part numbers: 203921B (Hercules Engine Co Inc), 208135 (Brinkley Technology Group Llc Dba Hercules Manufacturing), XTA25000-19 (Scovill Inc), 203921B (Brinkley Technology Group Llc Dba Hercules Manufacturing), 208135 (Hercules Engine Co Inc).

What NSN replaces 6685-00-527-6545?

There are 2 known substitutes for 6685-00-527-6545: 4730-00-530-7296, 2815-01-297-9113. Verify interchangeability with system specifications before substitution.

What are the specifications of 203921B?

Key specifications for 203921B: Operating Temp Rating: 106.0 FAHRENHEIT NOMINAL DEGF; Flow Control Device: CHOKE; Inside Mounting Surface to Valve Seat Distance: 2.120 INCHES IN; Thread Size and Series/type Designator: 1-1/2-18 UNEF. 16 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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