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Safety Relief Valve

Model / MPN: 646B-3-3/8-2 | NSN: 4820-01-516-3833
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
Disk Loading Method
Maximum Operating Temp
250.0 degrees fahrenheit single response
Minimum Operating Temp
-40.0 degrees fahrenheit
Connection Style
G46b plain (pipe) 1st end
Connection Style
G9 plain, optional en (pipe) 2nd end
Valve Operation Method
Connection Type
Threaded external pipe 1st end
Connection Type
Threaded internal pipe 2nd end
Adjustable Pressure Range
+40.0/+125.0 pounds per square inch
Thread Size
0.3750 inches 1st end
Thread Size
0.3750 inches 2nd end
Part Name Assigned By Controlling Agency
Differential area relief valve
Steel comp 303 body
Thread Series Designator
Npt 2nd end
Thread Series Designator
Npt 1st end

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646B-3-3/8-2 Cross Reference