A case study on b. liq. expanding vapor explosion and fireball after a railway accident with liq. PrH-BuH mixt. was given. A release of 10-12 t of the mixt. took place, the tank car contained 8-10 t of the mixt. during the explosion. The fireball duration was 15 s. The fire was extinguished after about 3 h. Two people were deadly injured during the explosion and fire. An inadequacy of common Champagne model in describing the fireball course was stated.