100days-a-year
Contributor
Heres my take from having about 300 fills done a year in a variety of Fla locations.Very few shops run banks hi enough to get a 3500 fill after it cools.A 3500 fill at the shop can often be 3100-3300 depending on how fast they fill.Most shops will fill lp tanks to 3000 without looking and they cool to 2700 to 2800 or a decent fill.Nitrox fills are often lower for some reason.I get 2900 or less in al80s a lot.Air seems to get jammed in and nitrox the take more time and are less likely to overfill.Aluminum conducts better so a 3200 hot fill often doesn't drop past 3000.The 3446 tanks sound like a good idea but like I said before a 3500 bank and a hp steel tank equal a lo fill.There are some exceptions but this is what my experience is.Having a bigger tank than you think is needed never hurt.A lot of people answer this question out of a book,real life ain't like the movies either.To properly fill a 3500 tank when your compressor cut-off is @ 3500 is just about impossible unless you top off several hours later and most shops just don't do it.BTW most compressors are rated 3000 to 3500.If it was yours and the repair bills came out of your pocket how would you fill?