“White Ghost” and PPV
Mark. A. Matthias
Sheboygan (WI) Fire Department
Sheboygan (WI) County Hazmat Team
I enjoyed Albert J. Kirk`s reply (Letters to the Editor, December 1995) to Frank C. Montagna`s article on the “White Ghost” (Training Notebook, May 1995). His reply was very detailed and informative. I have never encountered this phenomenon, and most of the veterans in my department with whom I`ve spoken have never experienced it either.
Kirk`s background on the subject seems to be quite extensive; and while his information describing the circumstances under which the “White Ghost” will appear is accurate, I would like to discuss the ventilation of the basement by firefighters in that incident. Since the event Kirk describes took place more than 10 years ago, I would have to agree with his assessment. Ventilation procedure then would have been to suck the smoke and vapors out of the basement by placing the smoke ejectors inside the building. This would have induced a negative pressure inside the basement and caused a reversal of draft in the boiler and its chimney.
The method of ventilation used for the past 10 years or so, however, has been “positive pressure.” Setting up a positive-pressure ventilation (PPV) fan from the outside and blowing air into the open basement door result in a positive pressure inside the basement. [Under the “White Ghost” circumstances described by Kirk,] the resulting positive pressure would, at the very least, not only have maintained the draft in the boiler and its chimney but more than likely would have increased it.
In addition, PPV is the ventilation method of choice for purging flammable gases and vapors from the interior of buildings. Setting up a fan to push fresh air into a structure to vent its contents is infinitely safer than requiring personnel to enter the building and its atmosphere to set up a fan to pull that atmosphere past the fan.
I`m looking forward to reading more correspondence on the “White Ghost,” and hats off to Fire Engineering for elaborating on this rare and potentially deadly occurrence.