Cathode Ray Tube (CRT) Safety



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  Cathode Ray Tube (CRT) Safety

(See also General Safety CEM 100 (87) )

The primary hazard of CRTs is flying glass as a result of an implosion. The following describe different phases of CRT safety. All phases are equally important and negligence in any area could result in possible injury to an employee or customer.

Any additional information or variation from this information will be included in CEM/Service Aids.

Storage of CRTs
  1.  Cathode ray tubes must be enclosed when received, transported, or otherwise moved from area to area.

     If they are shipped in a carton, they must be in the original carton or one of equivalent strength, and securely sealed to prevent  accidental opening. Also, original or equivalent pcking materials and forms must be placed inside the carton to give the CRT proper  support and protection. If CRTs are transported in a unit or piece of equipment, the equipment must be able to contain the glass  fragments should an implosion occur.

  2.  CRTs should be stacked as directed on the manufacturer's carton. When in doubt, stack with faceplate (viewing surface) down. Cartons should not  be stacked more than two high.
  3.  CRT storage areas must be away from the normal flow of material handling equipment and pedestrian traffic. Also, storage areas must be dry to ensure that cartons  will not absorb moisture and collapse.


Maintenance and Installation of CRTs
  1.  No one shall be permitted to install, adjust, maintain, replace, or handle high-vacuum CRTs until they have reviewed these instructions.
  2.  CRTs when received, transported, or otherwise moved from area to area should be completely enclosed in their original shipping cartons and sealed.
  3.  When handling CRTs, personel must wear safety equipment at all times. The minimum safety equipment required is:

    1.  Safety glasses - IBM part number 5715010
    2.  Long-sleeved garment.

  4.  CRTs under vacuum will not be permitted to remain out on their cartons unless they are under test or inspection.
  5.  Do not scratch or bump any part of the CRT because this may weaken the glass and cause it to implode.
  6.  Before removing any CRT, discharge all stored potential that may exist on the CRTs anode button or base socket pins and the capacitor in the high-voltage  supply. The procedures for discharging CRTs are explained in High Voltage Discharge Procedure  as part of the steps in removal and replacement.

    NOTE: Some CRTs contain a conductive coating on both the inside and outside surfaces to form a capacitor. Within some CRTs, a second capacitive charge builds  up following the original discharge. It is therefore important to discharge each CRT a second time immediately before removal.

  7.  Do not handle CTRs by the neck alone. The neck is the weakest part of the CRT and is easily broken. Always handle CRTs with two hands. If the CRT is shipped with a lifting  strap, use this strap for removing a CRT from, and placing a CRT into, the shipping container.
  8.  When CRTs are inserted or removed from equipment, they must be supported by the large end while carefully guiding the neck in or out of position. The lifting strap, if available, can  be used in this process.
  9.  Do not place the CRT on a table or bench when there is any possibility of the CRT rolling. If it is necessary to place a CRT anywhere except in its special carton, a piece of felt or other soft  material should be placed under it to prevent scratching the glass. Place larger CRTs vertically on their faces, and not on their sides, to prevent the possibility of rolling.
  10.  When a CRT is removed from equipment, it should be enclosed in its shipping container as soon as possible to reduce the chances of breaking. Cathode Ray Tubes should each be placed in their cartons with  the large face end up and the neck down. Ensure that the weight of the CRT is not resting on the neck. The container should be sealed securely with strong tape and, to prevent tipping, turned over so the  CRT is positioned face down.


Disposal of CRTs

Field personnel must not release the vacuum in CRTs. Dispose of CRTs in accordance with existing safe working procedure.


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