The horizontal tank in my 01 Hawk is out of date. When I realized it, I called around to the bulk propane suppliers in my area and learned the ones closest to me don't do the certification. However, they told me where I could get it done.
I did this some time ago but if memory serves, I called Amerigas and Suburban Propane locations and a couple of smaller independents in a 15 mile radius. The closest place that does certifications is a Suburban Propane about 25 miles from me.
That location told me the certification itself would be $15 but requires a purge of the tank so I'd also need a refill at $18.80.
The clerk told me the tank would have to be replaced after 5 years after that initial recertification but that's not true-- a tank can be re-certified again and again so long as it's still in good condition. The lesson there is it's best to do some research on the subject before taking the tank in.
In my case, I have a nearly-full tank in excellent condition so have chosen not to get it re-certified until the propane runs low. I've also been considering swapping out the 20# tank for two smaller ones but haven't yet done the research. (If anyone has swapped out a horizontal for two verticals, please post or PM me!)
Edited 5/10/17 for a correction. The location now says a purge of the tank is not required. See post #22.
Edited by Old Crow, 10 May 2017 - 01:12 PM.