Foster ST4F4-S Steel Quick Connect Plug (5 PACK) – 1/2" FNPT, FST Series Industrial Interchange

Model: ST4F4-S
Category: Pressure Washer Accessories → Quick Connect Fittings
Type: Foster ST4F4-S Steel Quick Connect Plug – 1/2" FNPT, FST Series Industrial Interchange (Pack of 5)

The Foster ST4F4-S Steel Quick Connect Plug (5 Pack) is a heavy-duty industrial coupling designed for high-flow fluid transfer and pressure washing applications. Built to the widely used FST (Straight-Thru) industrial interchange standard, this plug ensures compatibility with other fittings of the same series and size for reliable system integration.

Key Features

• Foster ST4F4-S steel quick connect plug (Pack of 5)

• 1/2" FNPT threaded connection

• FST Series straight-through design (no internal valve)

• Industrial interchange compatibility (same series/size required)

• Durable plated steel construction for heavy-duty use

• Manual sleeve operation for secure connect/disconnect

• Optional ball lock mechanism to prevent accidental disconnect

• Buna-N seals for reliable sealing performance

• Designed for maximum flow with minimal pressure drop

Technical Specifications

Product Name: Steel Quick Connect Plug
Brand: Foster (ZSi-Foster)
Model / Part Number: ST4F4-S
Series: ST / FST (Straight-Thru Industrial Interchange)

Connection Size: 1/2" FNPT
Material: Plated Steel
Seal Material: Buna-N
Operation Type: Manual Sleeve
Locking Mechanism: Ball Lock (Optional)
Flow Design: Straight-Through (No Valve)
Vacuum Rating: Up to 27" Hg

Pressure Rating: Per ANSI/B93.2-1986 (4:1 safety factor, non-shock service)
Quantity: Pack of 5
Fitting Type: Quick Connect Plug
Condition: New

Typical Applications

• Pressure washer hose and accessory connections

• Industrial fluid transfer systems

• Pneumatic and hydraulic line connections

• Steam cleaning and washdown systems

• High-flow applications requiring minimal pressure drop

• Applications requiring a 1/2" FNPT industrial interchange quick connect plug (FST Series)

⚠ Compatibility Note:
Only sockets and plugs within the same series and size will connect (e.g., matching prefix digits such as 25FS with 25MPB). Ensure proper pairing for safe and effective operation.