Bushing, Spigot x FPT (Flush Style) PVC Schedule 80 4" x 2-1/2" (838-421)

The 4" x 2-1/2" PVC Schedule 80 Flush Bushing (838-421) transitions a 4" solvent-welded socket connection down to a 2-1/2" female-threaded outlet in a single compact fitting — with a flush-style profile that seats recessed within the mating 4" socket rather than projecting outward from its face. The spigot end solvent-welds permanently into any standard 4" Schedule 80 slip socket upstream, while the 2-1/2" FPT outlet accepts any standard 2-1/2" male-threaded fitting, valve, nipple, or equipment connection downstream.

Positioned between the 838-420 (4" x 2") and the 838-422 (4" x 3") in the 838-series 4" inlet lineup, the 838-421 occupies the middle step-down in this segment of the series — suited to systems where the downstream threaded connection carries moderate flow that a 2" outlet cannot adequately support but where the full capacity of a 3" connection is not required or specified. The 2-1/2" FPT outlet is a less common pipe size than 2" or 3", and buyers sourcing the 838-421 are almost always working from an engineering document or equipment specification where 2-1/2" is the precise thread size called out at the downstream connection — a 2-1/2" threaded pump port, a valve body with a 2-1/2" MPT inlet, a strainer or filter assembly specified at 2-1/2", or equipment inlet threading that requires this exact size at the interface point.

The mixed spigot-and-thread configuration delivers the same core design logic as all 838-series flush bushings: the solvent-welded spigot inlet creates a permanent, pressure-rated upstream joint that becomes part of the surrounding Schedule 80 assembly, while the 2-1/2" FPT outlet keeps the downstream threaded connection fully removable — allowing male-threaded valves, instruments, strainers, or equipment connections at the outlet to be serviced, replaced, or reconfigured without disturbing the permanent upstream 4" joint. This permanent-upstream / serviceable-downstream configuration is a deliberate engineering choice over both the all-slip 837-series (where both ends are permanent) and the all-threaded 839-series (where both ends are removable), and it reflects systems where the bushing transition point itself is fixed but the downstream threaded equipment interface requires ongoing access.

The flush-style profile seats fully recessed within the 4" socket — avoiding the protruding hex head that would create clearance interference in tight mechanical spaces, close-coupled valve assemblies, and equipment rooms where the additional protrusion of a hex bushing would reduce working clearance or interfere with adjacent piping and components.

Manufactured to Schedule 80 specifications and dimensionally compliant with ASTM D2467, the 838-421 delivers the elevated wall thickness and pressure rating that Schedule 80 gray PVC is specified for in chemical processing, industrial fluid handling, and demanding commercial applications. Gray PVC construction provides broad chemical compatibility with acids, alkalis, and industrial process fluids. NSF 61 certification confirms suitability for potable water contact where required.

Specifications:

Industries & Applications:

• Chemical Processing — permanent-inlet, serviceable-outlet reducing transitions at 2-1/2" valve bodies, pump ports, and equipment connections in 4" chemical feed, dosing, and process fluid systems where the upstream joint is fixed but the 2-1/2" downstream connection must remain removable for maintenance
• Industrial Process Piping — reducing transitions from 4" solvent-welded Schedule 80 headers to 2-1/2" threaded valve, pump, or equipment connections in plant utility and process fluid systems where 2-1/2" is the precise downstream thread size specified in the system design
• Water & Wastewater Treatment — reducing transitions in treatment plant process piping where a permanent 4" slip-welded inlet feeds a serviceable 2-1/2" threaded equipment or valve connection at a designated service or access point
• Commercial & Industrial Plumbing — tight-clearance reducing bushings at valve isolation points and equipment connections in high-pressure mechanical systems where a 4" slip inlet must transition to a 2-1/2" threaded service connection in a single fitting
• Aquaculture & Food Processing — corrosion-resistant reducing transitions at 2-1/2" equipment and valve connections in recirculating systems and chemical-exposure fluid handling installations where the upstream 4" joint is permanent and the downstream connection requires periodic service
• Irrigation & Agriculture — 4" solvent-welded mainline-to-2-1/2" threaded valve or pump transitions in high-pressure chemical injection and large-scale irrigation distribution systems where 2-1/2" is the specified downstream equipment connection size