Safety Procedure

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This document provides a description of the department's method for detecting dangerous levels of oxygen and carbon monoxide. This is accomplished by what is called Oxygen Deficiency Hazard / Carbon Monoxide (ODH / CO) detection. This document describes ODH / CO, where ODH / CO detection takes place, and how levels of ODH / CO are displayed to plant workers.

OVERVIEW:

1. A gas mixture of low temperature, low oxygen gas and high temperature, low oxygen gas is piped into the Debind Zones of the kiln.
2. The low oxygen levels in the kiln's Debind zone gases could present a hazard in the surrounding areas if leaked out of the kilns or ducts. This could cause the potential elimination of or reduction in oxygen available to breathe. This is referred to as an oxygen deficiency hazard, or ODH.
   
   OHSA considers atmospheres containing less than 19.5% oxygen deficient.
3. Nitrogen gas is also used in the kiln to control the process as well as to prevent explosions. Nitrogen gas displaces the amount of breathable oxygen in the air, and therefore can cause an oxygen deficiency hazard if nitrogen leaks from the kilns or ducts.
4. High temperature oxidation occurs in the kiln's Graphite Removal zones to remove graphite from ware.
5. One of the byproducts of oxidation is carbon monoxide (CO) gas. Carbon monoxide at high levels can displace oxygen, which could present an oxygen deficiency hazard in the surrounding areas.
   
   A carbon monoxide hazard exists when carbon monoxide levels increase to 25 parts per million (ppm).
6. There are ten ODH / CO sample points located in the kiln area. Each ODH / CO sample point takes a sample of the oxygen and carbon monoxide levels in the air at that particular location.
   

   Location of ODH / CO equipment

7. The sample is sent to the ODH Main Control Panel located on the west wall in front of the kiln entrances. The sample is read by an oxygen sensor and carbon monoxide sensor located inside the Panel.
8. The levels are then displayed on the Panelview. From the Overview screen, oxygen is represented as Sensor 1 and carbon monoxide is represented by Sensor 2.
9. Push the Sensor 1 Points 1-8 OK or Sensor 2 Points 1-8 OK buttons to display the gas level screens for oxygen or carbon monoxide.
10. The gas levels screen displays the gas level and status for the each of the first eight ODH / CO sample points. Oxygen levels are displayed as a percentage and carbon monoxide as parts per million (ppm). The status should read Normal.
    

    Location of ODH / CO equipment

11. To view the last two ODH / CO sample points, push the Same Sensor NEXT 8 points button.
12. The Sequencer on Point Number box will show which ODH / CO sample point is being read by the sensors.
13. Oxygen and carbon monoxide readings can also be monitored at the Shared Services Control Cabinet in the Kiln Control Room.
14. From the Main screen on the Shared Services Panelview, push the ODH Screen button to bring up the ODH / CO display screen.
15. All 10 ODH / CO sample points are shown along with their last sample reading.
    

    Location of ODH / CO equipment

16. The readings for each sample point is shown below, the left reading is oxygen and the right is carbon monoxide.
17. In order to provide a visual indication of oxygen and carbon monoxide levels, ODH / CO amber and blue stack lights are located on top of the Shared Services Control Cabinet.
18. On the plant floor, there are three sets of ODH / CO stack lights. These are located south of kiln 1 adjacent to zone 119, between kiln 1 and kiln 2 next to the kiln 2 gas train, and north of kiln 2 adjacent to zone 119.
    

    Location of ODH / CO equipment

19. If the blue and amber stack lights are off, all ODH / CO sample points are reporting safe conditions.
20. If either blue or amber stack light is on, then one or more of the ODH / CO sample points reporting a dangerous or potentially dangerous condition. These conditions require attention and may be cause for evacuation from the tunnel kiln area.
    

    Click for ODH / CO stack light conditions

21. There are also three pit ODH / CO sensors that detect conditions from sample points located below ground. There is one for each Vestibule pit and one for the MIS Station pit.
    

    Location of ODH / CO equipment

22. Oxygen and carbon monoxide levels are shown on the display.
23. Green and blue indicator lights provide a visual indication of conditions. When the green light is on, the atmosphere in the pit is safe for entering.
24. When the blue light is flashing, the atmosphere in the pit is not safe and the pit should not be entered or occupied.