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CNG Adapter to refuel CNG tanks from CNG vehicle refuelling pump

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dickji

Dick Grimshaw
<div>For those of you who are fed up with paying outrageous prices for CNG at marinas and elsewhere, and are located in a region where CNG vehicle refuelling pumps are available, I atttach a pdf file of how to make an adapter that connects your CNG cylinder to a vehicle refuelling pump. The cost of such an adapter is about $130 and can be used over and over again.

Dick Grimshaw

<center><img src="http://morgan38.org/discus/icons/attachment_icon.gif" alt="CNG adapter"></center></div>
 
I see the attachemnt didn't work, so I am copying the text a nd image below:



13492.jpg

CNG adapter


Parts list for CNG Adapter

1) brass nut (LH thread) ' CGA 350 *
2) Brass nipple ' CGA 350 *
3) 'hydraulic Tee' high pressure** 1/4 inch
4) gage 0-4000 psi (Note: must be 'no oil' type. Oil filled gages may explode!
5) Sherex/OPW LE-36 (3600 psi) receptacle ***
6) Adapter ' joins Sherex /OPW to 'Tee' ****. The 'thread' on the Sherex end must be 9/16' straight thread.

Note: all fittings must be rated at 5000 (preferably 10,000) psi working pressure or higher. More is better.



* 'CGA 350' denotes 'CNG' fittings. Oxygen and other gases have a different CGA number. The fittings for different gases use different threads on their connections. Purchase these fittings and the gage from a welding supply shop. Total cost = $20.00. Most shops don't stock CGA 350 fittings and will have to order them for you.

** High pressure Tee can be purchased at a hydraulic marine supply or repair shop. Cost = $8.00.

*** Sherex adapter and receptacle assembly is purchased from the OPW Corp. Total cost = $90. Order by calling 513-870-3100. It is a quick disconnect, ball lock type fitting.

**** Adapter can also be purchased from a Marine hydraulic. The problem of refilling these tanks using any CNG vehicle refueling 'pump' is the fact that CNG powered vehicles are designed with SAE straight thread fittings. Our tanks are designed with NPT pipe thread fittings. This adapter (actually, the Tee) joins these two different thread styles together.

 
Dick
I don't use CNG so your ingenius adapter won't be of any value to me. What I would like to know is how did you get the photo to come up in the message area? A picture is worth a thousand words and sometimes one is needed to explain a point. Having the ability to show a photo in with the text is a great thing.

Jim
 
JIm,
A photo is great, but is everyone does this the bulleting board size will get unmanegable quickly, prehaps it is best if we dont know how he did it. Is there a file size lemit on postings?


Regards
Jose
 
Jose
Perhaps you are right. It's just that a photo can express an idea much quicker than words. Maybe if Al Tigner is monitoring the board, he can advise us as to whether photos will be a problem. And maybe Mr Anonymous can elaborate on his objection.

Jim
 
Not being mechanically gifted I purchased the same set up from Corp brothers a few years ago for about the same cost. The only thing you need be concerned about is the pressure setting at the station where you fill your tank. Most are set at 3000, 4000 lbs and some of the newer ones even more. Our tanks are to be filled at 2600. The actually tank will take the 3000 lbs and allot more but the emergency cap is set at about 3500, thus you may get the scare of your life when the emergency valve pops while filling. Check with your station before filling. That being said I filled my tanks for less than 25 cents. In Michigan I have found that the Mijers stores are installing cng.

John _/) _/) _/)
 
I just talked to Corp Brothers in RI, and their president says that they used to make this gadget but stopped out of safety concerns. The issue was that the tanks were only rated to something around 2000 psi, whereas the filling stations were going to 4000 psi.

Is this a new issue since your posting of 2005? Or was it an issue even then?
How do you control how much pressure gets into the tank?
 
If you go to a certified CNG refill station, or in some places, exchange location, they will tell you the requirements. CNG is safe but difficult to find sometimes. It is certainly better than alcohol, and probably better than propane. Propane tanks must be re-certified every few years. I have heard of CNG stoves being converted to propane and that might be an option.
Jim
 
Dick - you have to be careful with this, have you re-filled your tanks already?

CNG auto tanks fill to 3000 & 4000 psi. Your tank max psi is 2000 IIRC, with the pressure relief valve set even lower.

Near me there is a company called National Fuel Gas. They will fill for $40(Buffalo, NY). Perhaps there are natural gas supplier in other areas that will do the same.

As Jim correctly points out, CNG tanks are required to be inspected every 5 yrs for a reason! $20 well spent.

I have all the info & contacts for professionally filling CNG tanks. If there are listers nearby me we can work together and lower our costs. Problem is you can't ship tanks economically. "Hand deliver" only.

When I told my local cng bus & cng fuel pump company what I wanted to do (re-fill with adaptor), they said NFW. "Sailor with a death wish makes 6 pm news" No thank you!
 
Guy's Avery Seaman (owner of Corp Brothers ) is a thief. I use his New Bedford office but $ 36.00 to supply $ 1.00 of gas ( medium tank ) is a ripoff. Anyone notice the price of N.G. is going down? I exchange tanks so no worry about preasure, tanks I get are usually about 2300#.

Dick
 
Dick - just to put Corp Bros in perspective: We have a marina nearby who wants in excess of $135 to exchange CNG cylinders.

The place I get mine done is $40 for 1, then $1 for each additional tank. So the more tanks I have the less the fill per tank. 12 tanks would be $4.25 a tank.

You want a shocker - try adding up the costs to switch to propane with a proper propane locker /solonoid etc! I wouldn't live long enough to ever see the ROI!

Cheaper to take Momma to dinner every night. Then everybody wins! Till then I "shuffle of to Buffalo" as the song goes.
 
Dave: You must be on Erie or Ontario. When a kid too many years ago, spent 17 summers on Chautauqua! Wish I could get a second tank filled for $ 1.00

I put propane on my Cat 38, don't remember it being all that expensive, however the 10# tanks are hung off the stern pulpit so no locker problem. Am on my second solonoid in 12 years. Don't like using the aft locker on the Morgon for propane.

Dick
 
I followed the plan for the refill adaptor fairly closely and although it took some time to order all the parts, when they came there was no machining to do. They cost $130 including shipping. They all went together with nothing more than a wrench and vise. I drove the tank to the public refueling station at Newark airport; the connector worked fine; the fill-up took about 20 seconds; the only surprise was the pump agent who was wide-eyed that all he could charge me was $1.15 to fill the tank.
:clap

Previously, I was paying $140 for shipping a tank to Corp Bros, having it filled, and shipping it back. The cost of the new adaptor was thus amortized in a single use! The New Jersey gov is intent on encouraging the use of more CNG, and the cost of CNG is going down, so I am hopeful there will be more refueling stations emerging. That should create more of a market amongst boaters, and bring more CNG to the shore.
 
Hey guys,
I've worked in the natural gas pipeline industry for the past 33 years and wish that more CNG was avaiable for vehicles and vessels. Since the price of gas is now down to the $2.50 per million BTU range, that should change for us soon. I heard recently the equivelent price to gasoline is ~70 cents per gallon.
The big problem with using it as a mobile fuel source is the tankage required. CNG (methane) has far less heating value than LPG (propane). In fact, for the same cubic footage of gas, LPG is 2 1/2 times more BTUs than CNG.
CNG is certainly safer to use on a boat than LPG. If you develop a leak with LPG it will settle in the bilge and in low areas as it is about 150% the weight of air. CNG, on the other hand, is about 56% the weight of air and will float to the top and with hatches open will easily escape.
What type of tank are you using? How large is it? How long does it last?
Sorry about all the questions. I'm just wondering how economical it would be to switch to CNG.
Thanks,
Tommy
 
I built this unit, but I added a needle valve between the CNG supply hose and the pressure gage. This allows you to read the pressure in the tank and slowly fill it to it's rated pressure. It would not be safe to connect this directly to a 2250 psi tank and fill it to line pressure of 3000 or more. The safety blowout disk could blow out causing the gas to be released. I thought that it might not be a bad idea to install a regulator too, and set it to the rated tank pressure, but I didn't do it to mine yet.
By the way, last time I filled the thank it cost $0.65. Another option in our area is to take it to Milwaukee the the natural gas company. They charge $10 to fill it. The guy said "sorry, you are getting about $1.00 worth of gas, but they have to charge so much to cover my time."

Later I found out that the local marina with the exchange program is just loading their truck up and taking them to Milwaukee. The same guy fills their cylinders. Their exchange is $70. Not a bad markup. To be fair to the marina, and in consideration of their effort, they have to drive an hour each way, and probably spend an hour there. They probably take 7-10 cylinders there at a time. That would bring say $400-600 profit? That works out to about $200/hour. I'm in the wrong business.
 
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