Manual HPLC Valves, what we have and how they work13 Feb 2014
If you are looking for some manually activated valves to use with your HPLC system, we just might have what you are looking for. For each of these, the flowpath is controlled manually via knobs on their exterior. We’ll briefly discuss some commonly used valves and common applications here below.
To direct the solvent flow between one of two destinations, the Dual Stem Three-Way Valve, our catalog #26404 should work.
- To use for this application, the incoming solvent flow would be connected to the common port (in the center), which remains open continuously. To direct the flow to one side, you would turn one of the knobs counterclockwise to open the port on the same side and turn the other knob clockwise to close off the flow from the opposite side. To “switch” the valve and direct the flow out the other side, you would close the side that is open and open the one that is closed
Keeping both sides of the valve open, here is how you would configure it for other possible applications:
- To combine two separate flowpaths into one: Connect the two incoming flows to the two ports on the bottom side and then connect the output line to the single port on the opposite/top side of the valve.
- To split one flowpath into two streams: Connect the incoming flow to the single port on top of the valve. Connect the two outcoming streams to the two ports on the opposite/bottom side. This configuration works best if you are splitting the flow equally, and opening both sides of the valve all the way. If, instead, you need to split your flow into a specific ratio, please see our listing of post-column flow splitters.
We also have a Prime/Purge valve, which is catalog #26406. This is a generic part, not specific to any particular instrument, which directs the flow to bypass its normal path temporarily and is rated to handle up to 8000 psi. To either prime the pump or purge the system, the valve is opened by turning the external knob counterclockwise.
- To purge the flowpath: Connect the PTFE flanged tubing (provided with the valve) to the outlet port and direct it to a waste container. Turn the pump on and continue until all air is evacuated and/or solvent is replaced with a new supply as desired.
- To prime the pump: Connect a syringe to the outlet port (¼” -28 fitting size), which exits perpendicular to the other two ports, usually on top. Priming is done this way by pulling a vacuum with the syringe to draw out air, pulling solvent through to wet the pump’s internal surfaces. The syringe may be connected by attaching a large gauge needle and inserting tightly inside the flanged tubing.
We also have a two-way valve or what is sometimes called a “through-valve", which basically closes off a flowpath as needed.
The Angled Through-Valve, catalog # 26401
(Flow goes in one side and out the bottom, or vice versa.)
Lastly, we also have three-way valves which usually provide a vent by inserting an added path for flow or pressure to exit. In a sense, a “T” is either added or removed by turning off and on. These outwardly look the same as the two-way or through-valves, but their internal flowpaths look like this:
The Bottom-Vent Three-Way Valve, catalog # 26402
Flow is always open between A and B, flowing through from side to side. When the knob is turned counter-clockwise, C is inserted into the pathway also and vents or flows out the bottom.
The Side-Vent Three-Way Valve, catalog #26403
Flow is always open between A and B, flowing from side to bottom or vice versa. When knob is turned counter-clockwise, C is inserted into the pathway also and vents or flow out the other side as well.
Please note that the above vent valves are not used to direct flow between two streams as the Dual- Stem Three-Way Valve does. Instead, the above vent valves have all 3 ports open simultaneously when the valve is open.
I hope this has clarified a few things and increased awareness about the valves. Thank you for reading.