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,
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