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Safety Relief Valve

Model / MPN: 646B-1-1/2-2 | NSN: 4820-00-490-6714
ITAR Registered seal

A valve designed to automatically release excessive pressures. It is actuated by static pressure upstream of the valve and is used as a safety valve or relief valve, and may be set to close at a predetermined pressure. It is not designed for regulation of continuously fluctuating loads. It may be inline or cartridge (manifold) design. Excludes valve (1), relief, pressure and temperature.

Product Details
NATO Stock Number
Sold in multiples of
1 EA
Thread Direction
Right-hand 2nd end
Thread Direction
Right-hand 1st end
Flow Control Device
Disk Loading Method
Maximum Operating Temp
225.0 degrees fahrenheit single response
Connection Style
G46b plain (pipe) 2nd end
Connection Style
G9 plain, optional en (pipe) 1st end
Connection Style
Plain (pipe) 2nd end
Connection Style
Plain, optional en (pipe) 1st end
Valve Operation Method
Connection Type
Threaded external pipe 2nd end
Connection Type
Threaded internal pipe 1st end
Adjustable Pressure Range
+4.0/+15.0 pounds per square inch
Maximum Operating Pressure
3600.0 pounds per square inch single response
Thread Size
0.500 inches 1st end
Thread Size
0.500 inches 2nd end
Rubber synthetic seat
Stainless steel body
Stainless steel flow control device
Media For Which Designed
Air 1st response
Media For Which Designed
Hydraulic fluid, petroleum base 2nd response
Style Designator
Thread Series Designator
Npt 2nd end
Thread Series Designator
Npt 1st end

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646B-1-1/2-2 Cross Reference
  • 646B1 1-2 2