Burnin' Ring of Fire

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Across
  1. 2. reduces build up in boiler water
  2. 4. indicates water level on a steam boiler
  3. 7. byproduct of incomplete combustion
  4. 8. double block and ________
  5. 10. steam above saturation
  6. 11. wiring of safeties
  7. 13. cycles boiler based on setpoint
Down
  1. 1. boiler rating
  2. 3. normal operating water level
  3. 5. adds water to boiler system
  4. 6. returned to steam boiler
  5. 9. perfect combustion
  6. 12. safety device to prevent explosion