Making a heating tube

We now have a flexible gas system but I´m not completely done with this set-up. We can control the moisture content in the gas, but since it is a short distance between the evaporation module and the chamber, there is a risk for condensation. Preheating is therefore necessary. The gas connections have a diameter of 3mm and it was difficult to find an off-the-shelf solution for this small diameter. Making the heating solution ourself turned out to be very successful.

We bought different isolation materials from Karnag AB, which were sewed together to tubes by Slipgatans Möbelverkstad. This was done in several steps. First, an inner tube of a weave was made. In this tube a resistance wire was attached. Around the weave tube, a needle loom-felt was attached for isolation and then an outer weave with an aluminum coated surface for wear resistance. The resistance wire was connected to a power supply. It is important to be very careful with this type of arrangement if you need to use a high voltage. For the low temperatures we are after (below 100 degrees) we only use low voltage (25V, 0,8A) which is harmless if you happen to come in contact with the resistance wire.

Steps in making a heating tube of isolation fabrics, resistance wire and a power cable. The parts used for attachment of the power cable and the resistance wire was found inside two-screw terminals.