Parker 391PSS-4-2 Compression Pipe Coupler 1/8-27 Ss

Product Description

The PARKER 391PSS-4-2 is a compression tube pipe coupler body designed to connect compression tubing to a male NPT threaded port. Constructed from 316 stainless steel, this fitting provides reliable corrosion resistance in demanding fluid and gas handling applications. It features a 1/8-27 thread size with a compression-by-MNPT end connection configuration. The fitting is rated to a maximum working pressure of 150 psi and operates across a temperature range of 0 degrees F minimum to 65 degrees C maximum. Plumbers, pipefitters, and HVAC technicians install this type of fitting where a compression tube line must terminate at a threaded port on valves, manifolds, or equipment bodies.

This coupler body is suited for residential and light commercial piping systems where stainless steel construction is required for corrosion resistance or cleanliness standards. Common applications include instrument tubing connections, refrigeration and HVAC line sets, chemical handling, and hydraulic or pneumatic control circuits. The 1/8-27 MNPT thread makes it compatible with standard NPT-tapped ports found on a wide range of valves, gauges, and fittings. The compression end accepts tubing without soldering or brazing, enabling faster field assembly.

Key Features

• 316 stainless steel construction for excellent corrosion resistance in wet or chemical environments
• Compression x MNPT end connections for tool-assisted, no-solder tube-to-pipe hookups
• 1/8-27 thread size fits standard NPT-tapped ports on valves, gauges, and equipment
• 150 psi maximum working pressure rating
• Rated down to 0 degrees F minimum operating temperature
• Compact, lightweight design at 0.05 pounds — suitable for tight-clearance installations

Compatibility

Designed as an OEM-style compression tube pipe coupler for use in standard 1/8-27 NPT-ported systems requiring a compression tubing interface.

Installation Notes

Installation is performed by licensed plumbers, pipefitters, or HVAC technicians in accordance with applicable IPC and IFGC guidelines. Shut off all system pressure and depressurize the line before removing or installing any compression fitting. Hand-tighten the MNPT end into the receiving port, then use a calibrated wrench to snug — do not overtighten stainless steel threads, as galling can occur. Apply appropriate thread sealant or PTFE tape to the NPT threads per the system fluid service requirements.