As of now the special permit for the PST HP cylinders number SP9791 is due to expire on either the 31st of January or the 28th of February (depends on which government web site you're on)We had the same issue four years ago and at that time the permit was renewed. In that PST no longer exists the renewal is NOT a forgone conclusion. For those of you out there that have these cylinders it is in your best interest to research this and decide if you want to get them hydro'd now and guarantee another five years of service life or if you feel lucky and belive the permit will be renewed. The link below will take you to the government site that indicates Feb. 28th but be aware the hydro facility that I use found the January 31st date and that's the date they intend to go with
Capt. Al
SEA LION
http://www.phmsa.dot.gov/hazmat/regs/sp-a/special-permits/search