How to clean the ceramic insulators on a Waters instrument - WKB64189

OBJECTIVE or GOAL

Clean the ceramic insulators so that they maintain the voltage applied to the lens plate they hold.

ENVIRONMENT

• AutoSpec Premier
• GCT
• GCT Premier
• Quattro Micro GC
• Ceramic insulator

PROCEDURE

A number of procedures exist to clean ceramic insulators.

1. Using a plumbers blow torch or Bunsen burner: In a safe place away from any combustible material or gases, place the ceramics on a clean, thick-gauge, metal wire, draped between two support stands (like a necklace). The flame from a suitable torch/Bunsen burner plays across the ceramics until they change color (over 10 to 15 minutes). White ceramics go to a grey color and then return to white as they cool. Pink ceramics tend to lighten and then return to a deep pink as they cool. Degussit ceramics (AutoSpec) or any ceramic rods tend to break easily, so this procedure is not recommended for this type of insulator.
2. Place ceramics in a porcelain crucible and heat to 650 °C for >4 hours in a Muffle oven.
3. Place ceramics in various acid baths (located in a fume cupboard).
   • Set ceramics in a concentrated nitric/hydrochloric acid mixture in 1:3 volume ("aqua regia" or "Kings water") for 15 minutes.
   • Set ceramics in concentrated sulfuric acid for 15 minutes.
4. Use a suitable sand blaster to abrade ceramics with silicon oxide powder.

ADDITIONAL INFORMATION

1. In an anaerobic environment, the high temperatures and voltages that any organic compounds present will form CO₂, CO, and carbon. The carbon present will allow the voltage/current applied to a lens to pass across it and foul the insulator. Removal of this carbon contamination is necessary for the ceramic insulator to work correctly.
2. All of the the listed procedures carry health risks, and appropriate precautions must be taken.
3. In the acid bath treatment, the ceramics should be washed with copious amounts of MilliQ water. Add concentrated acid to water when disposing of the used concentrated acid.
4. All cleaning procedures weaken the insulating capacity of the ceramics and will cause them to fail over time. It is highly recommended that cleaned ceramic insulators be stored separately from new ceramic insulators.