7725I - Syringe Loading Injector w/Position Sensor

The IDEX Rheodyne Model 7725i is a six-port manual sample injector designed for precise sample introduction in analytical HPLC systems. Based on the proven 7725 platform, the 7725i includes a built-in position sensing switch that provides valve status feedback for chromatography systems requiring injection confirmation or signal synchronization.

The injector features a front-mounted built-in needle port for direct loop loading, supporting dependable manual injections with excellent repeatability. A 20 µL sample loop is supplied as standard, making the valve well suited for routine analytical HPLC workflows where consistent injection volume and reliable handling are critical.

The 7725i uses Make-Before-Break (MBB) valve architecture, which maintains continuous mobile phase flow as the handle rotates between the LOAD and INJECT positions. This uninterrupted switching design supports smooth chromatographic operation and dependable injection performance during manual use.

Constructed with stainless steel, ceramic, and inert polymer wetted materials, the Model 7725i is engineered for durability in demanding laboratory environments. The valve is rated for 345 bar / 5000 psi and temperatures up to 80°C, making it suitable for a wide range of analytical HPLC methods requiring reliable manual sample introduction.

Key Features

• Six-port manual injector for analytical HPLC applications
• Integrated position sensing switch for valve position feedback
• Front needle port for direct loop loading
• Make-Before-Break switching for uninterrupted flow during actuation
• Maximum pressure rating of 345 bar / 5000 psi
• Maximum operating temperature of 80°C
• Supplied with a standard 20 µL sample loop

Injection Flexibility

The 7725i supports both complete loop filling and partial loop filling depending on sample availability and method requirements. Complete loop filling offers the highest injection precision because the loop defines the injected volume. Partial loop filling is useful when sample quantity is limited and the syringe determines injection volume.

This flexibility makes the valve useful for routine analysis, method development, and laboratory workflows where sample volume, throughput, and reproducibility all matter.

Position Sensing Advantage

The primary difference between the 7725 and 7725i is the built-in position sensing switch. This switch confirms whether the injector is in the LOAD or INJECT position, allowing chromatography systems or data platforms to monitor valve status during operation.

This added functionality is especially valuable in workflows where manual injection must be coordinated with data acquisition, timed events, or system-level validation.

Supplied with the Valve

The Model 7725i is supplied with the accessories needed for installation and routine operation, including fitting sets, hex keys, mounting hardware, vent tubing, needle port cleaning tools, and a 20 µL sample loop.

Maintenance and Serviceability

The injector is designed for long-term service with replaceable wear components such as the rotor seal and stator face assembly. For routine maintenance, a dedicated RheBuild™ kit is available to support ongoing valve performance and extend service life.

Typical Applications

The Model 7725i is ideal for laboratories needing a manual HPLC injector with electronic position feedback, dependable loop-based injection, and durable analytical-scale performance. It is especially useful in chromatography workflows where repeatability, operator control, and system integration are all important.