Parker 391PSS-6-4 Compression Pipe Coupler 1/4-18 Ss

Product Description

The PARKER 391PSS-6-4 is a compression tube pipe coupler body designed to connect compression tubing to a male NPT threaded pipe fitting. Machined from 316 stainless steel, this fitting provides corrosion resistance suited for demanding fluid and gas line applications. It features a compression end on one side and a male NPT (MNPT) end on the other, allowing a direct transition between compression tube and threaded pipe systems. Rated to a maximum working pressure of 150 psi, the 391PSS-6-4 is a reliable choice for plumbing, instrumentation, and process piping installations where stainless steel construction and leak-free compression connections are required.

This coupler body is suited for residential and commercial plumbing, HVAC, and light industrial applications where a compression-to-male NPT transition is needed. Common install scenarios include connecting copper or stainless tubing runs to threaded pipe manifolds, control valves, or instrumentation ports. The 1/4-18 NPT thread size is standard in many plumbing and instrumentation assemblies. Licensed plumbers, pipefitters, and HVAC technicians working with refrigerant lines, pneumatic controls, or water supply systems will encounter this fitting type regularly.

Key Features

• 316 stainless steel construction provides strong corrosion resistance in wet and chemically active environments
• Compression x MNPT end connections allow direct tube-to-threaded-pipe transitions without soldering or welding
• 1/4-18 NPT thread size fits standard plumbing and instrumentation pipe threads
• Rated to 150 psi maximum working pressure
• Compact, lightweight design at 0.06 pounds for easy handling in tight spaces

Compatibility

Designed as an OEM-style compression tube pipe coupler body for use in compression-to-male NPT fitting applications across plumbing, HVAC, and instrumentation piping systems.

Installation Notes

Installation should be performed by a licensed plumber, pipefitter, or qualified HVAC technician. Shut off and depressurize the supply line before making any connections. Hand-tighten the compression nut first, then use an appropriate wrench to achieve a snug, leak-free seat without over-torquing the fitting body. Apply thread sealant or PTFE tape to the MNPT threads in accordance with local plumbing codes and the International Plumbing Code (IPC) where applicable.