Parker 398PSS-4-4 Shutoff Pipe Coupler 1/4 in Compression X Mnpt

Product Description

The PARKER 398PSS-4-4 is a single end shutoff pipe coupler designed for use in compressed gas and fluid line applications where a quick, positive shutoff is required at the tube end. Constructed from 316 stainless steel, this fitting connects a 1/4 inch outside diameter compression tube to a 1/4-18 male NPT threaded port. It is rated for a maximum working pressure of 150 psi. The compression end provides a leak-resistant, tool-assisted seal on the tube, while the MNPT end threads directly into a valve body, manifold, or instrument port. Plumbers, HVAC technicians, and instrumentation mechanics typically install this fitting in process lines, refrigeration ancillary circuits, and instrument tubing runs.

This coupler is suited for residential and light commercial applications involving compressed air, water, oil, or compatible instrumentation fluids. The single end shutoff configuration allows the line to be isolated at the fitting point, making it useful in service scenarios where a section of tubing must be capped or disconnected without draining an entire system. Its stainless steel construction makes it appropriate for corrosive or wet environments where brass or carbon steel fittings would degrade over time.

Key Features

• 316 stainless steel construction resists corrosion in wet and chemically aggressive environments
• Single end shutoff design allows line isolation at the fitting point
• Compression x MNPT end connections suit both tube and pipe installations
• Rated to 150 psi maximum working pressure
• 1/4 inch tube outside diameter and 1/4-18 NPT thread size for standard instrument and service line work
• Compact, lightweight at 0.12 pounds

Compatibility

Designed as an OEM-style replacement or direct-install fitting for systems using 1/4 inch outside diameter compression tubing terminated to 1/4-18 male NPT ports in plumbing, HVAC, or instrumentation applications.

Installation Notes

Installation should be performed by a licensed plumber, HVAC technician, or qualified instrumentation mechanic. Depressurize and isolate the line completely before disassembling any existing fittings or threading this coupler into a port. Hand-tighten the MNPT end first, then apply wrench turns per standard pipe fitting practice without over-tightening, which can crack fittings or distort threads. Apply appropriate thread sealant or tape to the NPT threads in compliance with applicable IPC or IFGC guidelines for the fluid or gas being conveyed.