Glass Press-Fit Unions
Glass unions can be sealed with polyimide sealing resin which ensures a leak-free and solid connection. This method is recommended if glass press-fit unions are used. While the union is permanently attached to the tubing, it is easy to cut out the union and install another one.
Instructions for Using Polyimide Sealing Resin with Glass Press-fit Unions
Note: Tubing and union cleanliness are critical to obtain a leak-free and secure union seal.
1. Clean the glass press-fit union with acetone and allow to air dry.
2. Score the tubing 1-2 cm from the end using a ceramic wafer, diamond tipped pencil or sapphire scribe. Do not break the tubing at this time.
3. Hold the open end of the column upward. Rinse the outside of the tubing (in the area of the score) with acetone.
4. Place a small spot of resin on a Kimwipe. Carefully apply a thin layer of polyimide sealing resin around the tubing and over the previously made score.
5. While still holding the column in the upward position, break the column at the score.
6. Inspect the end with a 10-20X magnifier. If the cut is uneven or jagged, repeat the scoring and resin application process.
7. Place a small amount of resin on one side of tubing about 0.5 cm from the end.
8. Insert the tubing into the glass union and press firmly.
9. On the side where the drop of resin was applied to the tubing, there should be a drop of resin that fills the gap between the union and the tubing. Add a small amount of resin to this area if an air gap is present. Do not fill into the entire union. This drop of resin helps to anchor the tubing to the union and prevent vibrations from weakening the seal.
10. Carefully install the column into the GC and establish carrier gas flow.