6-Port Valves

6 Port Valves can be purchased with either of two flow paths: The distribution flow path and the loop flow path.  The distribution path connects a seventh port on the back of the valve to one of the six remaining ports.  The loop flow path is commonly used for injectors in chromatography systems.

The Loop Flow Path 

The Loop geometry allows the user to select between two possible flow paths.   

Building an injector for a chromatography setup

An injector can be made using the following port assignments: port 1: pump, port 2: column, port 3: Sample loop end A, port 4: sample injector, port 5: waste, port 6: Sample loop end B.  With the valve set where the pump and column are connected, the sample loop can be filled by injecting the sample cia port 4.  The valve is then turned to the configuration where the pump is connected to Sample loop end B and the pump will push solution through the sample loop and into the column.

6-6 valve

Here is a link to the Hamilton 6-6 valve.  The November 2024 price was $190.

Holding the valve body

For the hexagonal valve body, we used a CNC router to mill a mount out of wood. We chose oak for this prototype because it was handy at the time. The mount could have been made of cast acrylic or aluminum or any other rigid material.  We feel it is important to have the mount attach to the black hexagonal part of the valve rather than the silver threaded piece because the threaded piece is able to turn in the black body.

A note on servo motors

The six port valve is larger than the 2-3 valve discussed in the introductory page to valve automation and it requires more torque to turn.  This may mean using stronger (and more expensive) motors.  Here is a link to a servo with a reported torque that is three times that of the servo linked to on the previous page.  I have not prototyped with the current generation of servo motors, so I don't really know what is going to work.  The other thing to keep in mind is the range.  The 3-2 valve will need to be able to turn 90 degrees.  The 6-6 will need to turn 60 degrees.  A distribution valve like the 6-1 will need to turn 300 degrees in order to connect to all six side ports.  Note that the servo linked to on this page is reported to have a 300 degree range.