Inline Check Valves

Idex check valves

IDEX check valves provide reliable one-direction flow control for chromatography and laboratory fluid-handling systems. Designed to prevent backflow and protect sensitive upstream components, these valves are ideal for HPLC, UHPLC, microfluidics, post-column derivatization, and sample-delivery applications where consistent flow direction is critical.

Multiple configurations are available, including standard inline check valves, biocompatible non-metallic check valves, inline cartridge check valves, and Quick-Stop luer check valves. All designs deliver low cracking pressure to maintain stable flow while minimizing pressure loss. Most IDEX check valves connect directly to 1/4-28 flat-bottom ports, eliminating the additional tubing cuts and connections required by traditional inline check valves. They accept fittings for 1/32", 1/16", 1/8", and 1.0–3.0 mm OD tubing, allowing seamless integration into existing systems.

Standard Inline 1/4-28 Check Valves offer excellent chemical resistance and spring-actuated sealing to prevent backflow without added plumbing complexity. Non-Metallic Check Valves provide biocompatible flow paths with ultra-low swept volume (as little as 7.4 µL), making them ideal for lab-on-a-chip, single-cell analysis, and micro- or nano-LC workflows. Inline Cartridge Check Valves are commonly installed on the effluent side of columns to prevent post-column reagents from flowing backward and contaminating analytical columns during pump shutdowns.

For applications requiring fast connect/disconnect convenience, the Quick-Stop Luer Inline Check Valve enables spill-free connections using standard 1/2-28 flat-bottom fittings, simplifying maintenance while reducing exposure to hazardous fluids.

Chrom Tech offers a broad selection of IDEX check valves and compatible fittings to support dependable backflow prevention, simplified installation, and optimized system performance. Many popular configurations are in stock and ready to ship.

Part No Description Threads Swept Vol Thru-Hole Max Pressure Back Pressure Cracking Pressure
STANDARD 1/4-28 INLINE CHECK VALVES
CV-3301Inlet1/4-28 FB, M to 1/4-28 FB, F20 µL0.020" (0.50 mm)2,000 PSI (138 bar)45 PSI (3.1 bar)15 PSI (1 bar)
CV-3302Outlet1/4-28 FB, M to 1/4-28 FB, F20 µL0.020" (0.50 mm)2,000 PSI (138 bar)45 PSI (3.1 bar)15 PSI (1 bar)
CV-3315Inlet1/4-28 FB, M to 1/4-28 FB, F16 µL0.020" (0.50 mm)2,000 PSI (138 bar)10 PSI (0.7 bar)3 PSI (0.2 bar)
CV-3316Outlet1/4-28 FB, M to 1/4-28 FB, F16 µL0.020" (0.50 mm)2,000 PSI (138 bar)10 PSI (0.7 bar)3 PSI (0.2 bar)
NONMETALLIC 10-32 MICRO-VOLUME INLINE CHECK VALVE
CV-3500Inlet/Outlet10-32 C, F to 10-32 C, F7.4 µL0.010" (0.25 mm)3,000 PSI (207 bar)25 PSI (1.7 bar)8 PSI (0.6 bar)
NONMETALLIC 1/4-28 & 10-32 INLINE CHECK VALVES
CV-3320Inlet1/4-28 FB, M to 1/4-28 FB, F37 µL0.020" (0.50 mm)2,000 PSI (138 bar)30 PSI (2.1 bar)1 PSI (0.07 bar)
CV-3321Outlet1/4-28 FB, M to 1/4-28 FB, F37 µL0.020" (0.50 mm)2,000 PSI (138 bar)30 PSI (2.1 bar)1 PSI (0.07 bar)
CV-3322Inlet1/4-28 FB, M to 1/4-28 FB, F49 µL0.040" (1.0 mm)2,000 PSI (138 bar)30 PSI (2.1 bar)1 PSI (0.07 bar)
CV-3323Outlet1/4-28 FB, M to 1/4-28 FB, F49 µL0.040" (1.0 mm)2,000 PSI (138 bar)30 PSI (2.1 bar)1 PSI (0.07 bar)
CV-3324Inlet1/4-28 FB, M to 1/4-28 FB, F182 µL0.060" (1.60 mm)2,000 PSI (138 bar)30 PSI (2.1 bar)1 PSI (0.07 bar)
CV-3325Outlet1/4-28 FB, M to 1/4-28 FB, F182 µL0.060" (1.60 mm)2,000 PSI (138 bar)30 PSI (2.1 bar)1 PSI (0.07 bar)
CV-3330Inlet/Outlet1/4-28 FB, F to 1/4-28 FB, F34 µL0.020" (0.50 mm)2,000 PSI (138 bar)30 PSI (2.1 bar)1 PSI (0.07 bar)
CV-3335Inlet1/4-28 FB, F to 10-32 C, M49 µL0.020" (0.50 mm)2,000 PSI (138 bar)30 PSI (2.1 bar)1 PSI (0.07 bar)
CV-3336Outlet1/4-28 FB, F to 10-32 C, M49 µL0.020" (0.50 mm)2,000 PSI (138 bar)30 PSI (2.1 bar)1 PSI (0.07 bar)
CV-3340Inlet/Outlet10-32 C, F to 10-32 C, F34 µL0.020" (0.50 mm)2,000 PSI (138 bar)30 PSI (2.1 bar)1 PSI (0.07 bar)
PART NO DESCRIPTION SWEPT VOLUME
QUICK-STOP LUER CHECK VALVES
P-696 Quick-Stop Luer Check Valve Assembly 127 µL
P-697 Quick-Stop Luer Check Valve 107 µL
P-699 Bulkhead Quick-Stop Luer Valve 107 µL
INLINE CARTRIDGE CHECK VALVES
CV-3000 Inline Check Valve Assembly for 1/16" OD tubing 96 µL
CV-3001 Inline Check Valve Cartridge for CV-3000 91 µL
CV-3010 Inline Check Valve Assembly for 1/8" OD tubing 100 µL
CV-3011 Inline Check Valve Cartridge for CV-3010 92 µL
Key Definitions â–¸
Cracking Pressure
The pressure required for a check valve to open in the direction of the arrow (forward flow direction).
Maximum Pressure
The maximum pressure the valve can experience in the reverse direction without leaking backwards (backflow).
Back Pressure Created
The amount of back pressure generated by the check valve with 50 mL/min room-temperature water flowing in the direction of the arrow.
Flow Direction Arrow
A marking on the valve body that indicates the intended forward flow direction. Check valves are designed to open with forward flow (arrow direction) and resist flow in the reverse direction.
Frequently Asked Questions â–¸
Where should I place a check valve in an HPLC solvent line?
For low-pressure solvent delivery, a check valve is commonly installed between the solvent reservoir and the pump. Using a Quick-Stop Luer Check Valve Assembly with the valve oriented toward the bottle helps prevent solvent leakage from the reservoir line and reduces the chance of spills during solvent changes. Keeping both lines full of solvent can also help reduce the need to reprime the pump.
Can a Quick-Stop Luer Check Valve be used for FIA sample injection?
Yes. The Quick-Stop Luer Check Valve provides a convenient way to introduce sample into FIA and other low-pressure systems when used with a compatible valve tee (for example, a pressure relief valve tee). A standard luer-tipped syringe can be attached for injection—the valve opens when the syringe is connected and closes when the syringe is removed, helping minimize mess and exposure.
How do check valves help in post-column derivatization setups?
For post-column derivatization, placing an inline cartridge check valve (for example, a CV-3000) on the effluent side of the column helps prevent derivatizing agents from flowing backward and potentially poisoning the column. Placement on the post-column reagent line can also help prevent mobile phase from contaminating the reagent if an auxiliary pump fails.
What check valve setup helps protect helium sparging (degassing) lines?
In sparging/degassing lines, an assembly designed for 1/8" OD tubing (such as a CV-3010 Assembly) can help prevent solvent backup if sparging gas runs out. This reduces the risk of solvent cross-contamination and helps protect the gas regulating valve from damage.
How do I orient a check valve and why does direction matter?
Install the valve so forward flow matches the arrow direction on the valve body. Check valves are engineered to open in the arrow direction and resist reverse flow. Correct orientation supports proper opening at the rated cracking pressure and improves backflow protection under reverse pressure conditions.