Plugs & Caps

Idex Plugs and Caps

IDEX Plugs & Caps provide a simple, reliable solution for sealing unused ports and tubing in chromatography and fluidic systems. Designed for both temporary storage and long-term system protection, these components help prevent contamination, solvent evaporation, and accidental leaks when a flow path is not in use.

Available in a wide range of thread sizes and configurations, IDEX plugs and caps are compatible with common port standards including 6-32, 6-40, 10-32, 1/4-28, M6, and 5/16-24. They can be used to safely seal instrument ports, fittings, valves, and tubing ends across HPLC, UHPLC, and general laboratory fluid handling applications.

Choose from multiple materials and styles to match your chemical compatibility and pressure requirements—whether you need a low-profile cap for storage, a threaded plug for instrument protection, or a reusable solution for routine maintenance.

Chrom Tech is an authorized distributor of IDEX fluidic components and stocks a broad selection of plugs and caps for fast shipment. If you need help selecting the correct thread type or material for your system, our team is ready to assist.

Part No Description Port Head Style Material
Plugs
P-123 Plug 1/4-28 Flat-Bottom 5/16" Hex ETFE Natural
P-309 Plug 1/4-28 Flat-Bottom Standard Knurl Delrin® Black
P-311 Plug 1/4-28 Flat-Bottom Standard Knurl ETFE Natural
P-314 Plug M6 Flat-Bottom Standard Knurl ETFE Black
P-316 Plug 1/4-28 Flat-Bottom Standard Knurl PFA Natural
P-321 Plug, FlushNutâ„¢ 1/4-28 Flat-Bottom FlushNut PEEK Natural
P-520 Plug 10-32 Coned 5/16" Hex Stainless Steel
P-550 Plug, Extra Long 10-32 Coned Standard Knurl PEEK Natural
P-551 Plug 10-32 Coned Standard Knurl PEEK Natural
P-555 Plug 6-32 Coned Standard Micro Knurl PEEK Natural
P-556 Plug 5/16-24 Flat-Bottom Standard Knurl PEEK Natural
P-558 Plug 6-40 Flat-Bottom Micro Headless Knurl PEEK Green
P-849 Plug 10-32 Coned Standard Knurl Delrin® Black
U-467R Plug 10-32 Coned Standard Knurl Delrin® Red
VHP-600 VHP Plug 10-32 Coned 3/8" Hex PK-SST
Caps
P-754 Cap 10-32 Coned Standard Knurl ETFE Yellow
P-755 Cap 1/4-28 Flat-Bottom Standard Knurl ETFE Black
P-756 Cap M6 Flat-Bottom Standard Knurl ETFE Blue
Key Definitions â–¸
Plugs
Threaded components used to seal unused instrument ports, valves, and fittings to prevent leaks, contamination, and solvent evaporation.
Caps
Closure fittings designed to cap off open tubing ends or external threads to protect fluidic pathways during storage or system shutdown.
Thread Size
The specific thread standard (e.g., 6-32, 10-32, 1/4-28, M6) that determines compatibility with instrument ports and fittings.
Flat-Bottom Port
A port design where the sealing surface is flat rather than coned, requiring specific plug or cap geometries for proper sealing.
Chemical Compatibility
The ability of plug or cap materials (such as PEEK, PPS, or stainless steel) to resist degradation when exposed to solvents and reagents.
Pressure Rating
The maximum operating pressure a plug or cap can safely withstand without leaking or failure.
Frequently Asked Questions â–¸
What are IDEX plugs and caps used for?
IDEX plugs and caps are used to seal unused ports, fittings, valves, and tubing ends to help prevent leaks, contamination, and solvent evaporation during storage, maintenance, or system reconfiguration.
How do I choose the correct thread size?
Match the plug or cap thread to the receiving port or fitting standard. Common options include 6-32, 6-40, 10-32, 1/4-28, M6, and 5/16-24. If you’re unsure, identify the instrument port type or reference the fitting specification for the component you’re sealing.
Are plugs and caps compatible with coned and flat-bottom ports?
Some plugs and caps are designed for coned (coned-seat) ports, while others are intended for flat-bottom ports. Always confirm the port style and select a plug or cap designed to seal properly against that geometry.
What materials are available and how do I pick one?
Material selection depends on solvent compatibility and pressure requirements. Polymers like PEEK or PPS are common for broad chemical resistance, while stainless steel is often chosen for maximum durability and higher pressure capability. When in doubt, match the plug/cap material to the rest of your wetted flow path.
Can I reuse plugs and caps?
Many plugs and caps are reusable if the threads and sealing surfaces are undamaged and the material has not been degraded by solvent exposure. Replace components that show stripped threads, deformation, cracking, or persistent leakage.
When should I use a cap versus a plug?
Use a plug to seal an internal threaded port (such as an instrument port or valve port). Use a cap to close off an external threaded fitting or to cap an open tubing end, depending on your system configuration and the component being protected.