Coffee Break Training: Access and Water Supplies: Fire Flow Formulas: Part 12: Insurance Services Office Needed Fire Flow: Exposure Factors [open pdf - 548KB]
The learning objective of this Coffee Break Training is that "the student will be able to explain the 'exposure factor' variable, Xi, in the Insurance Services Office (ISO) Needed Fire Flow (NFF) formula."
Coffee Break Training - Fire Protection Series No. FP-2013-47
United States Fire Administration: http://www.usfa.fema.gov/