Bushing, MPT x FPT (Flush Style) PVC Schedule 80 1/2" x 3/8 (839-073)

This 1/2" × 3/8" Schedule 80 PVC Flush Bushing provides a compact, all-threaded one-step size reduction from a 1/2" female-threaded port down to a 3/8" female NPT threaded outlet in a small-bore Schedule 80 PVC pressure system. The 1/2" MPT exterior threads directly into any compatible 1/2" FPT port — on a tee branch, cross outlet, valve body, instrument manifold, equipment nozzle, or threaded coupling — while the 3/8" FPT interior receives any compatible 3/8" male-threaded fitting, nipple, valve, or instrument component on the reduced side.

The one-step reduction from 1/2" to 3/8" spans two of the most prevalent small-bore NPT sizes in commercial and industrial piping. At the inlet, 1/2" NPT is one of the most common pipe sizes in small-bore Schedule 80 systems — appearing across branch supply lines, instrument supply mains, chemical dosing headers, small equipment connections, and control system piping throughout industrial and commercial facilities. At the outlet, 3/8" NPT serves an intermediate instrument and control system role — appearing at instrument isolation valve ports, select instrument body inlets, fine-bore chemical injection branch connections, and small-bore manifold ports where the system or equipment manufacturer specifies a 3/8" NPT connection rather than the more common 1/4" gauge-port standard.

The 1/2" inlet distinguishes the 839-073 from its small-bore sibling the 839-052 (3/8" × 1/4") in both application breadth and governing pressure rating. Where the 839-052 operates within the narrower context of instrument manifold piping and gauge isolation valve assemblies where 3/8" inlet ports are the norm, the 839-073 serves the broader population of 1/2" FPT ports across general small-bore Schedule 80 systems — a more prevalent port size that appears at a wider range of fitting types, valve bodies, and equipment connections throughout a typical industrial or commercial installation. When a 1/2" FPT port must interface with a downstream component presenting a 3/8" male-threaded inlet, the 839-073 accomplishes the full transition at the port face in a single fitting.

As with all 839-series fittings, the all-threaded MPT × FPT configuration is the defining feature distinguishing this bushing from the 838-series spigot × FPT flush bushings. The 839 MPT end threads into female-threaded ports; the 838 spigot end cements into slip socket ports. When the 1/2" port to be reduced is female-threaded, the 839-073 is the correct selection. No solvent cement, primer, or curing time is required at either end; the complete assembly — installation into the 1/2" FPT port and connection of the 3/8" downstream component — is accomplished with PTFE tape and thread sealant in a fully threaded assembly.

The flush style eliminates the protruding hex shoulder of a standard hex bushing, producing a low-profile assembly that installs cleanly inside the receiving 1/2" FPT port without adding axial projection beyond the port face. In small-bore instrument and control system piping — where fittings are often closely spaced at manifold ports, valve body outlets, and panel entry points — the absence of a hex shoulder preserves clearance between adjacent connections and keeps the assembly compact within the limited space available at each port position.

Manufactured in dark gray Schedule 80 PVC, this bushing delivers the wall thickness and mechanical strength required in industrial, chemical, and commercial pressure piping where Schedule 40 ratings are insufficient. PVC's broad chemical resistance covers acids, bases, salts, chlorine, and most common process and instrument fluids, providing long service life in corrosive environments where metal bushings would degrade, pit, or introduce metallic contamination into instrument lines and chemical handling systems. NSF/ANSI 61 listing confirms suitability for potable water contact.

Rated to 850 psi at 73°F (governed by the 1/2" MPT end), this bushing handles the full range of pressures encountered in commercial and industrial small-bore Schedule 80 PVC systems. At small NPT thread sizes, over-torquing is a primary cause of fitting failure — apply two to three wraps of PTFE tape to the 1/2" MPT exterior before threading into the receiving port, then hand-tighten plus one to two turns using a small open-end or adjustable wrench on the bushing body. Apply PTFE tape to all male threads engaging the 3/8" FPT outlet before installing downstream components; 3/8" NPT connections should be hand-tight plus one to two turns — do not apply pipe wrench torque at this small thread size. Apply published pressure derating factors for service temperatures above 73°F.

Specifications:

Industries & Applications:

• Instrument Supply & Control System Piping — Reduces a 1/2" FPT port on a Schedule 80 PVC tee branch, instrument manifold outlet, or small-bore valve body to a 3/8" NPT connection for instrument isolation valves, analyzer inlets, and small-bore control system components specified at 3/8" NPT in industrial and commercial PVC pressure systems — the defining application for the 1/2" × 3/8" size combination
• Industrial Process Piping — Provides a compact all-threaded one-step size reduction at 1/2" FPT branch positions on Schedule 80 PVC process headers, chemical distribution lines, pump manifold outlets, and equipment supply connections in chemical processing, water treatment, and manufacturing facilities where downstream components present 3/8" male-threaded inlets
• Chemical Dosing & Injection Systems — Installs at 1/2" FPT ports on chemical dosing manifolds, injection assemblies, and reagent distribution headers where 3/8" NPT back-pressure regulators, fine-bore flow control valves, or small-bore chemical metering components must be connected in systems handling acids, caustics, and aggressive process fluids
• Water & Wastewater Treatment — Reduces 1/2" FPT instrument and branch connection ports to 3/8" NPT fittings and valves on Schedule 80 PVC process headers, chemical feed manifolds, pump station piping, and filter vessel instrument connections in municipal and industrial water treatment and distribution facilities
• Commercial Plumbing & Mechanical Systems — Provides a one-step all-threaded size reduction at 1/2" FPT branch outlets on Schedule 80 PVC manifolds, threaded tees, and valve body ports where 3/8" NPT downstream components — small-bore shutoff valves, instrument connections, or fine-bore branch fittings — must be connected in building mechanical room and utility system piping
• Irrigation & Agricultural Systems — Reduces 1/2" FPT branch ports on threaded tees and zone manifold assemblies to 3/8" NPT connections for fine-bore control valves, chemical injection components, and small-bore instrument connections in commercial irrigation headers, greenhouse distribution systems, and agricultural water supply networks
• HVAC & Mechanical Systems — Installed at 1/2" FPT ports on Schedule 80 PVC cooling tower chemical feed lines, treated water monitoring headers, and glycol system branch connections where 3/8" NPT valves, meters, or instrument components must be connected at small-bore branch positions in commercial mechanical system piping