CNG Tank Refills

Sep 17, 2012
99
Morgan 383 Fairhaven, NY
I believe my tanks had a pressure relief valve. IIRC, it releases at 2500psi. So fill working pressure was 2200psi. In the video, the tank went over 3000psi. Interesting! An auto CNG tank fills to 3500psi or more. So the potential for "excitement" exists if the PRV blows off.

I gave some thought to building an adapter as seen in the video. Ultimately, I decided that having the tanks inspected for integrity ($30) and filled by a pro was money well spent. Compared of course to a local marina who wanted $170 for a single tank exchange. If I filled 4 tanks it got down to $11 each.
 
  • Helpful
Likes: jon hansen
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
... I realize that this is for autos and trucks but its a starting point for phone calls for your fill.
Not so. I know people with CNG tanks on their boat for the cook stove, maybe the grill. I guess they don't have to fill too often during the season. Frend of mine bought a C34, THEN told me what he bought came with the CNG stove. I'da suggested he not buy that
boat.
 

TomY

Alden Forum Moderator
Jun 22, 2004
2,758
Alden 38' Challenger yawl Rockport Harbor
I believe my tanks had a pressure relief valve. IIRC, it releases at 2500psi. So fill working pressure was 2200psi. In the video, the tank went over 3000psi. Interesting! An auto CNG tank fills to 3500psi or more. So the potential for "excitement" exists if the PRV blows off.
I once had a "blow off" in a quiet anchorage.

Instant unnatural ROAR!!! I thought I'd been sent for,...then I realized by the gas smell in the air what the source was (the CNG vent fitting I was sitting next to).

Likely the sun warmed that area over the tanks and one was borderline over-filled.

2500, 3500 PSI, DIY fill up, heat up your tanks, aiyiyi. I'd hate to think I got through Covid-19 only to be blown to bits filling my CNG tanks.