How to choose an Eluent Safety Cap

Usually, chromatography systems use 1/8'' (~3.2mm) O.D. capillaries for solvent extraction, but sometimes (for example, at the needle wash), you may come across a smaller O.D. tubing. Vision Eluent Safety Caps are available with standard fittings for 1/8'' tubings (VLA-A01), although our standard capillary port is uniform, you can easily replace the fitting to match the capillary. For all available fitting sizes, please see page 12.

In most cases, a 2-port safety cap works fine for solvent extraction as you use one eluent mixture with one capillary, and one port is always needed for the Air Filter. But if you would like to use an eluent for multiple pumps or washing, you need to use more ports. Safety caps are available with up to 6 positions. Nevertheless, all unused ports must be closed by a blind plug (VLA-A02).

If the HPLC pump works and extracts the eluent from the bottle, it causes a vacuum in a closed system. To avoid this, you need to use pressure compensation. For this reason, we suggest using our Vision Eluent Safety Shut-off Valve (VLV-SF1), which is a one-way valve - on the inlet side, it contains a 0.22µm PTFE membrane, on the outlet side is a silicone duckbill valve. In normal usage, the membrane can accumulate dirt, and the duckbill valve can wear out, so it is mandatory to change the Air Filter every six months. The best visible indicator that it is time to change the filter is the Timestrip sticker. After the Air Filter installation, just start the Timestrip sticker by slightly pushing the button until a straight red line is visible on the screen. After 6 months the screen will become red, then you will know to change it.