We have tabulated answers to common questions about the Sterile Tube Fuser. Please call or email if you have a question that is not covered here.
| Question | Solution |
| Can I reuse the cutting blades? | In theory yes. We do not recommend reusing the blade because of the potential for cross-contamination and compromise of blade construction. The blade gets some tubing residue during operation and this must be cleaned thoroughly if the blade is to be reused. |
| I notice that there is a small ridge on the inside of the weld. How does this affect flow? | The weld forms a small ridge on the inside and outside surface. The inside ridge is typically about a 1mm high and poses no significant flow restriction (similar to a barbed fitting). If you think the ridge is excessive, it can be reduced, but this may compromise the tensile strength of the welded connection. |
| My weld does not appear to be strong. What's wrong? | Check that the tubing is aligned properly. If not, return for service. Make sure you are letting the tubing cool completely before pulling at the weld. It takes 4 to 5 minutes for the full weld strength to develop. |
| Can I weld silicone tubing? | No. Only thermoplastic tubing can be joined. |
| Can I use the same machine to join different types of tubing? | Yes, within the same composition family. However, some tubing types may require blade temperature and timing adjustments. The unit can be configured at the factory. These parameters can also be programmed later by the user. |
| Can I use the machine in a cold room? | Yes. It may be necessary to adjust the fan speed for the lower ambient temperature. |
| The tubing connection appears to be misaligned. What do I do? | The alignment is checked by proximity sensors. Machines do not need frequent realignment but if tubing connection misalignment is a problem the machine must be returned for service. |
| What tubing diameters can I join? | Typical tubing diameters used are: 3/4
inch OD – 1/2 inch ID nominal flowrate possible
= 10 lpm Other tubing diameter holders are available. The standard STF-IR can handle all these sizes using interchangeable tubing holders. Holders can be exchanged in a few seconds. |
| What tubing brands work well? | Pharmed, Norprene are excellent. CFlex works well. Tygon and PVC can be joined. You can also join dissimilar tubing, such as Pharmed to CFlex. If you have a thermoplastic tubing brand not listed here that you would like to join, please send us a sample for evaluation. |
| Can I validate the machine for use in GMP production? | Yes. The machine is in use for GMP operations with major companies. Please look at the Validation Guide and Sample Protocol for suggestions on how to develop a validation program. |
| Can I weld filled tubing? | Not on the standard STF-IRc model. The liquid in the tubing
will drip into the unit. However you can pump or squeeze out the liquid from
the section to be welded. Small droplets do not affect the welding process. Yes, on the new STF-IRc WW model. Liquid-filled tubing from 1/4 to 5/8" OD may be welded using a specially designed tubing holder and clamping system. |
| Can I fuse autoclaved/irradiated tubing? | Yes. The STF was designed to work with autoclaved/irradiated tubing. |
