INITIAL OPERATION OF NEW X-RAY TUBES

The successful installation of an x-ray insert in its housing is dependent on a number of factors. They include the setting of filament current to manufacturer’s recommendations, cleanliness of the insert and its insulating media and, appropriate “seasoning in” and warm up procedure.

Cleanliness of the tube head environment is especially important in order to ensure long and trouble free operation of the new insert. Special attention is needed to determine that the insulating oil is clean and free of contaminants; including carbon, metallic particles, and moisture. This is best accomplished with the use of an inline oil filtering system and fresh, clean insulating oil is needed. “Open” type systems are especially sensitive to oil conditions and should be thoroughly checked.
Contamination of the oil or, SF6 gas in gas insulated tubes, may lead to insert punctures which typically occur from “outside in” to the glass envelope. Moisture, dust, particles or carbon formations can cause such problems. The extra care in maintaining a clean insulating environment will pay off in reliable and extended tube life.

The initial seasoning in and warm up of the new insert is similar to the start up of an unit idle for a number of weeks and can be accomplished in one to two hours on a 320 kV tube. There are some events that occur during the seasoning in process that are important to understand.

The glass envelope of the tube is an insulator as we know, and a very good one. In fact it is too good and tube manufacturers use various methods to impart a small quantity of conductivity on the glass. LOHMANN X-Ray uses a metallization to the inside of the glass envelope. This infusion is formed and stabilized in the electrical field during the seasoning of the new tube in its housing. This formation can be easily observed as reactions of the tube, bursts, as it nears the maximum operating voltage.

The tube can be run slowly to its maximum potential with the reactions noted being both necessary and expected. The reactions are then an indicator of abnormal tube running through the metallization and stabilizing process.

After the tube has reached its maximum voltage and stabilized the  reactions will not reoccur. The tube is now ready for satisfactory service.

Your technical questions are always welcome. We will provide the information you need for the service and operation of your LOHMANN tubes.