CNG Tank & Refill Question

[markr]

Hi All,
A search for CNG reveals a lot of posts on the subject.
I am specifically trying to find out the following. I am in San Diego and the tank looks like a scuba tank and is fitted under the seat in the aft cabin:
1. My tank appears old and is not certified (or I do not have the paperwork for that). How do I get it certified? It is white painted with spots of rust. It looks original....
2. How do I get a new tank(s) if mine fails certification/I want another one as backup onboard?
3. What is the deal with this adaptor to fill from a gas station - would I need one and if so where would I get it?

The tank has run out for the first time and I need a workable system for CNG refills as I move forward.
(No, I do not intend to convert to propane - and yes I know personally of two people who were badly injured, one losing a leg, due to a propane explosion on a boat, and in that case a lack of propane safety procedure)

Thanks,
Mark

[Stu Jackson]

1. My tank appears old and is not certified (or I do not have the paperwork for that). How do I get it certified? It is white painted with spots of rust. It looks original....
2. How do I get a new tank(s) if mine fails certification/I want another one as backup onboard?
3. What is the deal with this adaptor to fill from a gas station - would I need one and if so where would I get it?

1.  No certification is required.  You usually swap them out for filled ones.

2.  www.safgas.com shows suppliers.  I have a spare on board, too.  Good idea.  Buy one.

3.  The adapter is on the wiki.  The idea is that you make one and then get it filled at a CNG place rather than swapping tanks.

[Jeff Kimbel]

Mark -

In order to get a CNG tank filled, it must have a current Hydrostatic test date, stamped on the top, near the neck of the cylinder.  The stamp will have a month, test station id, and year  (ex:  6 X 99) would be from June, 1999.  The hydro test is only valid for 5 years.  So, check the top of your tank (you may have multiple stamps), and see if you can find one from 2005 or later.  If not, among other places, the easiest place to get a hydro test done may be your local scuba diving shop.  You should find that they charge around $25 or $30.  Years ago, I also took a tank to a local fire department, who sent it to their source and did not charge me.

Sorry - I can't help you with a source for tanks.  As for sources of CNG, I contacted my local public utilities vehicle service center, where they have a CNG filling station for their vehicles.  They only charge me $15 to fill the tank.

Hope this helps -

Jeff

[markr]

Pearsons Fuel dock on Shelter Island, San Diego. The exchanged my CNG tank for a filled one ($34). They had a spare tank someone had given them and they sold it to me for $70, plus refill at $34. So I walked away with two filled tanks. Yippee!
Still working on someone to price me a cost for making that adaptor from the techwiki - it is beyond my meagre handyman abilities. The adaptor may be a better long term solution - i.e. filling at the gas station CNG outlet - but I assume that to do that I will have to have my current tanks checked and certified.....?

This raises another question tied in with my "blue water cruising" search for information - how prevalent is CNG outside of the States? This could be a practical issue. A conversion to propane may be a possibility, but I would rather not. If I did change to propane, I would look for another solution to a self draining gas locker as an alternative to the photos I have seen of a locker on top of the steering quadrant in the aft lazerette. This seems to block the storage potential of this locker....perhaps off to the side would be better?

I am currently installing a below decks Raymarine autopilot and as part of that we have removed the wood from the top of the steering quadrant and replaced with a longer piece that goes all the way to starboard. The starboard side would be a good place to put in a propane locker? Since I now have two CNG tanks I am thinking that this elongated shelf would may be the best placxe to store the second tank - by fitting straps onto the wood and lashing the tank down athwartships...

Just some thoughts>......

[Stu Jackson]

1.  Still working on someone to price me a cost for making that adaptor from the techwiki - it is beyond my meagre handyman abilities. The adaptor may be a better long term solution - i.e. filling at the gas station CNG outlet - but I assume that to do that I will have to have my current tanks checked and certified.....?

2.  This raises another question tied in with my "blue water cruising" search for information - how prevalent is CNG outside of the States? This could be a practical issue. A conversion to propane may be a possibility, but I would rather not.

3.  If I did change to propane, I would look for another solution to a self draining gas locker as an alternative to the photos I have seen of a locker on top of the steering quadrant in the aft lazerette. This seems to block the storage potential of this locker....perhaps off to the side would be better?

4.  I am currently installing a below decks Raymarine autopilot and as part of that we have removed the wood from the top of the steering quadrant and replaced with a longer piece that goes all the way to starboard. The starboard side would be a good place to put in a propane locker? Since I now have two CNG tanks I am thinking that this elongated shelf would may be the best placxe to store the second tank - by fitting straps onto the wood and lashing the tank down athwartships...

5.  Just some thoughts>......

1.  It's hard to price 'cuz times change and things change price.

2.  It simply isn't avialable outside the US.  Period.

3.  That's one of the reasons people change fuel. If you do some more looking around the website (this message board using searches, the wiki, Projects and FAQs), you'll find propane locker solutions either in the lazarette (under the helmsmans seat) or in the port locker.  Those are the ONLY two interior places.  A friend of mine with a Tartan 37 built an outside rack for a tank out of starboard hose clamped to his pulpit.  

4.  Our spare CNG tank is in the port sette just forward of the holding tank.  The PO drilled a large hole in the bulkhead to the area under the V berth portside drawers, that fold down door, so the pointy end of the tank with the valve fits through the hole.  Works great:  foam or some kind of insulation below, doesn't have the same kinda of wooden "rack"that the main tank has in the aft cabin.  Those tanks are very heavy and I would be hesitant to locate them in the lazarette unless there's a way to lay them down, which is the best configuration for them - laying down.

5.  I believe Ron Hill has copyrighted that phrase!  

[Ron Hill]

 5. Clarification : My copyright on that phrase only applies when used with propane tanks!!   

[markr]

Just posted details in the for sale section for someone who can build the CNG tank adaptor for you as per the tech wiki - for $119.85. If you are interested, look him up in the for sale section on my post. Made in San Diego, but he will ship it.....

[dgill]

Hi Mark,

Just to let you know, it is easy to make your own adapter for refilling the CNG tank.  Stu posted all the parts necessary to accomplish this.  It takes a bit of internet searching to find a local supplier and one trip to a machine shop, but I recall I had mine completed in a couple of weeks.

What you would need to determine is whether your state has a public CNG refill area.  Here in Maryland we do.  Many of the buses and taxi cabs and local government vehicles are run on natural gas.  The pump is accessed by using your credit card.  I made my own adapter and have been refilling my CNG tank for several seasons now.  Cost to refill an empty tank .96 cents - not the $50 to $100 charged by those that stock the refilled tanks.  This was money well spent.  Good luck.

D. Gill
#389

[Stu Jackson]

My friend's Tartan 37, I just noticed yesterday, has two of the smaller (small-ish? smallest?) propane aluminum tanks.  That makes sense because then he's not tied into one tank that can go empty at just the wrong time.  Isn't it funny how the active tank always goes out when you're cooking???

I pay $20.24 to swap a tank.  It was $16.14 for about ten years until the price went up last year.  Someone's ripping you off if it costs $100 for a swapout.

Just posted details in the for sale section for someone who can build the CNG tank adaptor for you as per the tech wiki - for $119.85. If you are interested, look him up in the for sale section on my post. Made in San Diego, but he will ship it.....

Mark, if you're going to identify a reference source, I've learned it is really helpful to provide a direct link to the post so folks can get there easily.  Thanks.

[markr]

Here is an attempt to post a link to my message in the for sale section about a source for building the adaptors:

http://c34.org/bbs/index.php/topic,5531.0.html

It may be uiseful for those who don't/won't/can't build their own, and perhaps are worried about it being correctly spec'd for the high pressures involved. Here in San Diego there are plenty of CNG filling stations for vehicles, which is where the adaptor can be used.

Personally, I am happy for now to have two CNG tanks on board. If I was planning on heading away from the US, I would probably convert to Propane and put a locker somewhere aft (self-draining of course!).

Stu, if the link thing is wrong, please let me know and I will correct it. Thanks.

[Stu Jackson]

Thanks, Mark, the link works.  What I usually do when posting a link is to post my thread and then try it out.  Sometimes I catch an incorrect copy & paste.  Thanks again, great idea.

[tom475]

I know this is an old topic, but I feel I should share with all my sucess. We are in SW Michigan and a local marina charges $69 for an exchange of CNG. We located a CNG filling station and decided to make the adaptor from the wiki. We filled our tank yesterday for the first time and the cost was $2.06. Thanks to all.  Tom

[Brent]

When I got my 1988 Catalina 34 surveyed,before purchasing,  the report said the CNG tank cannot be located in the locker in the back berth.  If I have it relocated to under the helm, does CNG have to be in a separate locker or can it be hung in the transom?  He also recommended an Auto Shut Off switch.  Where can that be purchased and where should it be mounted?  Thanks.

[Stu Jackson]

WADR, that is not true.  Only the regulator has to be vented to the outside.  There is a barb on the regulator to do just that. Your surveyor doesn't know the difference between propane and CNG.

[chuck53]

My CNG tank is located under the small settee in the aft cabin.  My surveyor had no problem with its location due to the fact it was CNG.  And unless I've missed something, I don't recall seeing any kind of venting on my tank or regulator.