FLYING TIMES

Balloon Size	Flying Time	Balloons per 170 cu. ft. tank (approx.)
9" latex	5-10 hrs.	650
12" latex	10-20 hours	300
14" latex	15-25 hours	170
17" latex	30-40 hours	100

All times are approximate for indoors, putting balloons outside can reduce the flying time by 50%.  Another factor is the actual size of the balloon.  Inflating too much will cause them to burst in 5 to 10 minutes.  Inflating too little will reduce the flying time.  Other factors include temperature, humidity, sunlight and little children with sharp objects.