Cathode-Ray Tubes

Electron Tubes Cathode-Ray Tubes Electron tubes are fairly rugged devices. Most of them can handle the shocks and knocks of everyday use. However, they are not indestructible. Most electron tubes contain a near vacuum enclosed by glass. Any excessive stress, like dropping the tube, may cause the glass to shatter, causing an IMPLOSION. A n implosion is the opposite of an explosion. When the glass shatters, the outside air rushes into the tube to fill the vacuum. As the air rushes into the tube, it carries the glass fragments with it, right on through the center of the tube and out the other side. If you’re in the path of these flying fragments, you could be seriously injured. So, handle ALL electron tubes with care. Some electron tubes contain radioactive material. These must be handled with EXTRA care. Radioactive material is added to some electron tubes to aid ionization. Unbroken, the radioactive tubes are as safe as other electron tubes. This is because the tube’s radioactive material emits slow-moving particles that are contained within the tube’s thick glass envelope. But breaking the tube will expose the hazardous radioactive material. To prevent injury to yourself or others, use the following safety precautions when handling either regular or radioactive tubes: 2. Immediately put any electron tube that has just been removed, whether radioactive or not, into a protective container, such as its shipping container. 3. Let your supervisor know immediately if a radioactive electron tube is broken. 4. Seal off a radioactive-contaminated area immediately so no other personnel are exposed to the radioactive material. 5. Treat all bad or damaged radioactive electron tubes as radioactive waste and dispose of them accordingly. 6. Do Not remove a radioactive tube from its shipping container until you’re ready to install it. 7. Do Not let your skin come in contact with any radioactive fragments. If it does, wash yourself thoroughly with soap and water and get medical attention. Cathode-ray tubes (CRTs) are everywhere. They’re used in televisions, desktop computers, radars, and electronic warfare systems. You’ll probably maintain electronic systems that use CRTs. So, it’s important for you to know about their hazards, and how to handle and dispose of them. CRT hazards: CRTs can be extremely hazard- ous. A CRT consists of a large glass envelope that main- tains a high vacuum inside. It also has a toxic phosphor coating on its face. CRTs are under great atmospheric pressure. For example, a 10-inch CRT is subject to nearly 2,000 pounds of force. Of that, 1,000 pounds is felt on the tube’s face alone. Therefore, if you break the glass envelope, it will cause a violent implosion. When a CRT breaks, high external pressure causes it to implode (burst inward). As a result, all the glass fragments, metal parts, and toxic phosphor are expelled violently. A CRT can also be hazardous when it’s energized. This is because it carries a very high voltage and emits X-rays. CRT handling: To protect yourself from serious injury, you must never do anything that would cause the CRT’s glass envelope to break and cause an implosion. When handling CTRs, follow these precautions: 1. Handle A L L election tubes, whether radioactive or not, with EXTREME care. 1. Always follow the manufacturer’s handling instructions. 2. Keep a new CRT in its shipping carton until you’re ready to use it. 3. When you remove a defective CRT, place it in a shipping carton immediately. 4. Wear gloves and goggles. 5. Do Not remove a CRT until the high-voltage anode has been discharged. 6. Do Not strike or scratch the surface of a CRT’s glass envelope. 7. Do Not stand in front of a CRT when you install it. If the CRT should implode, the electron gun in its neck could be propelled at a very high velocity through the face of the tube and into your body. 8. Do Not carry a CRT by its neck. 9. Do Not come in contact with phosphor coating; it is extremely toxic. If a CRT should break, 2-8