We keep our CNG in scuba tanks and we need to refill but the nozzle at the refilling station doesn't fit. Need suggestions for an adaptor.
CNG Refilling
- Thread starter Tumororlater
- Start date
John, many folks have made them. Steve Dion, on this board, has one.
It's mechanical parts. Terror doesn't enter into it.
One could say the same about the ones made by Joe the Plumber in the factory on a late Friday afternoon or a Monday morning after the Super Bowl in Seattle.
I have CNG on our boat, and don't lose any sleep over it. I make sure the connections are made properly and tightened properly, too.
Your boat, your choice.
It's mechanical parts. Terror doesn't enter into it.
One could say the same about the ones made by Joe the Plumber in the factory on a late Friday afternoon or a Monday morning after the Super Bowl in Seattle.
I have CNG on our boat, and don't lose any sleep over it. I make sure the connections are made properly and tightened properly, too.
Your boat, your choice.
The original question claims that the CNG is stored in "scuba tanks." Hopefully that's not the case. Though they resemble scuba tanks, the tanks approved for CNG are much thicker and heavier in order to withstand the pressures involved.
I'm with you on the home brew adapter.
Stu, you and Steve are aware of the dangers involved and you know what you are doing but we do not need a horde of home fabricators perhaps using cheap components and thinking they are dealing with something similar to Propane to descend on the CNG filling station endangering their lives and those of others. The number of existing CNG rated portable tanks is quickly dwindling by attrition as the manufacture of new ones may be coming to an end as manufacturers respond to the market. What then, you think they may start using scuba tanks that may no longer be suitable to hold compressed air?John, many folks have made them. Steve Dion, on this board, has one.
It's mechanical parts. Terror doesn't enter into it.
One could say the same about the ones made by Joe the Plumber in the factory on a late Friday afternoon or a Monday morning after the Super Bowl in Seattle.
I have CNG on our boat, and don't lose any sleep over it. I make sure the connections are made properly and tightened properly, too.
Your boat, your choice.
Don't get me wrong, I used to do things with Propane before the ABYC that would send some contributors into a fit, but I felt I knew what I was doing and perhaps the fact that never had an incident may attest to the fact that I was careful and still am. Some Scuba steel tanks are not rated to hold over 2800 PSI.
Benny, good point about the scuba tanks, I missed that. Otherwise, the idea of building your own refill adapters, WITH THE RIGHT MATERIALS as detailed in my link, is a choice each skipper needs to make. I haven't because I have a tank replacement place right down the street from my marina as well as a backup tank on board. Steve Dion has always graciously offered to refill my tank(s) if I'm up his way in the Delta ($2.45 vs. $25 per tank). Mine last a tad beyond six months with weekly use for coffee and a two might cruise every week or two.
Stu, did not expect any less from you, like I said you and Steve know what you are doing. What I'm concerned is the less knowledgeable who might thinks it is OK to fabricate an adapter with cheap components and has no idea of the high pressure CNG is stored at and the danger it represents. That is a sweet deal you have, I never had CNG as I grew up overseas where there is little availability and I got used to propane but I recognize it is an ideal fuel for marine use and too bad the market for portable tank filling is drying up.
CNG tanks resembling scuba tanks. Have been hydraulically tested. Where can I order the parts listed in the diagram? I have 15mm opening in my tank valve.
I have built an adapter myself based on the instructions floating around. I use it all the time and I pay 80 cents to refill my tank to 2100 PSI. I control the pressure of the refill, being aware, a hot fill will result in lower pressure when the tank cools, so always fill a cold tank as slow as practical (by throttling a needle valve). My modification consists of the addition of a needle valve to control the flow rate to the tank and thereby the ultimate fill pressure. I fill at local vehicle fueling stations but you must be VERY careful as they are all 3000/3600 PSI - way over the limit for the steel tanks. Vehicle fueling goes FAST - you could blow up the tank if you are not controlling the fill pressure. That is why you should have a needle valve, pressure gauge (any good local hydraulic supply company) and seal the threads with the high pressure sealant - again, hydraulic supply company should give you a few drops no charge make sure you tell them you are working with CNG.
I don't know anything about using aluminum tanks (typically 80 CF and good to 3000 PSI), but due to moisture/corrosion potential I would probably stay away from them myself. When its time for a new tank, I will by a NEW steel tank or a proper CNG tank. The thing about tanks made for CNG is that CNG has a potential to have moisture content and you have no way of knowing it, and thereby can corrode the the tank - no problem as long as you never let it go to 0 PSI, and always inspect it. The new CNG tanks are epoxy coated or fiberglass coated to eliminate that issue but they have limited lifetimes and don't allow hydro after 10 years..... However, you will still have the 2250 PSI issue unless you can confirm your regulator on your boat will handle 3000 PSI.
The fact is the steel SCUBA tanks (72CF) work fine (up to 2250 PSI you can get higher, but look for the rating. 2250 is orig equip.) as long as they are hydrostatically tested and properly maintained. When they do get corrosion, they roll it with steel pebbles and clean out the corrosion, then Hydro it again every 5 years. Outside of that you are playing roulette if you don't.
Just my 2 cents. I like the CNG, I appreciate the instructions on building the gizmo.
I don't know anything about using aluminum tanks (typically 80 CF and good to 3000 PSI), but due to moisture/corrosion potential I would probably stay away from them myself. When its time for a new tank, I will by a NEW steel tank or a proper CNG tank. The thing about tanks made for CNG is that CNG has a potential to have moisture content and you have no way of knowing it, and thereby can corrode the the tank - no problem as long as you never let it go to 0 PSI, and always inspect it. The new CNG tanks are epoxy coated or fiberglass coated to eliminate that issue but they have limited lifetimes and don't allow hydro after 10 years..... However, you will still have the 2250 PSI issue unless you can confirm your regulator on your boat will handle 3000 PSI.
The fact is the steel SCUBA tanks (72CF) work fine (up to 2250 PSI you can get higher, but look for the rating. 2250 is orig equip.) as long as they are hydrostatically tested and properly maintained. When they do get corrosion, they roll it with steel pebbles and clean out the corrosion, then Hydro it again every 5 years. Outside of that you are playing roulette if you don't.
Just my 2 cents. I like the CNG, I appreciate the instructions on building the gizmo.
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'later,
This is another chance:
I want a new emoticon:
LEASE read the blinkin' links: Please, please, please.
The link I provided has a website and phone numbers. For fittings and pipe/threads, Jamestown Distributors is often cited by skippers here, or McMaster Carr.
If the link provides incorrect or out of date info, I haven't heard of that recently in posting this recurringly.
If you do find inocrrect or outdated info, please, just let me know.
Here is the latest info, from my build. However, I must caution you that you should have some understanding about gas laws, pressure and mechanics. If not, get it from the suppliers, or just buy the refilled cylinders. While this is safe if you follow safety rules (as long as you fill only to the rating of your pressure vessel and the adapter parts) it can also be lethal if not assembled properly and used properly.
I give no warranty to the safety or acceptability of the parts listed below. I will post a photo of the gizmo tonight.
Parts list for CNG Adapter
1) brass nut (LH thread) CGA 350 NPT
2) Brass nipple CGA 350
3) hydraulic Tee high pressure** 1/4 inch (5000 PSI)
4) gage 0-4000 psi (Note: must be not oil type. Oil filled gauges may explode)
4.5) Needle valve (rated to 5000 PSI) to control fill and reduce pressure fill in tank
5) NGV1 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.
Sources:
High Pressure: Thread Adapter & needle valve, hydraulic Tee high pressure
Hydraulics & Pneumatics, Inc. (505) 884-1110
3207 Claremont Avenue Northeast
Albuquerque, NM 87107
Argyle welding: gauge, brass nut CGA 350, Brass nipple CGA 350
1575 Candelaria Blvd, NE Albuquerque, NM 87197
Phone: (505) 345-8101
Sherex/OPW LE-36 (3600 psi) Manufacture specifications:
http://www.opwglobal.com/Product.aspx?pid=145
Actual Source/distributor:
http://westechequipment.com/product/4216/le3?cPath=1_60_3185_2588_2592&
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 gauge 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.
**** 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.
"Live in the sunshine, Swim in the sea, Drink the wild air. " -- Ralph Waldo Emerson
I give no warranty to the safety or acceptability of the parts listed below. I will post a photo of the gizmo tonight.
Parts list for CNG Adapter
1) brass nut (LH thread) CGA 350 NPT
2) Brass nipple CGA 350
3) hydraulic Tee high pressure** 1/4 inch (5000 PSI)
4) gage 0-4000 psi (Note: must be not oil type. Oil filled gauges may explode)
4.5) Needle valve (rated to 5000 PSI) to control fill and reduce pressure fill in tank
5) NGV1 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.
Sources:
High Pressure: Thread Adapter & needle valve, hydraulic Tee high pressure
Hydraulics & Pneumatics, Inc. (505) 884-1110
3207 Claremont Avenue Northeast
Albuquerque, NM 87107
Argyle welding: gauge, brass nut CGA 350, Brass nipple CGA 350
1575 Candelaria Blvd, NE Albuquerque, NM 87197
Phone: (505) 345-8101
Sherex/OPW LE-36 (3600 psi) Manufacture specifications:
http://www.opwglobal.com/Product.aspx?pid=145
Actual Source/distributor:
http://westechequipment.com/product/4216/le3?cPath=1_60_3185_2588_2592&
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 gauge 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.
**** 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.
"Live in the sunshine, Swim in the sea, Drink the wild air. " -- Ralph Waldo Emerson
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Not from what I found. I don't think they want the liability. What you would need to make this safe is a pressure regulator preset to the pressure rating on the tank you are filling. The needle valve is the poor mans regulator, but requires you keep your head out of the dark place.... :naughty:
Actually I have found sites that sell higher pressure steel tanks for scuba, rated at 3000 PSI. That would be the safe option, plus give you more gas. I know my tank, which was original equipment, is only Hydro'd for 2250, as stamped on the tank. I don't know what the threads are, but they are probably standard. I have "heard" of folks saying the regulator will work up to 3000 PSI on the front end, but I could not find any specifications or markings on it that made me believe that and I am not willing to bet my life on it. I will just fill to 2250, maybe get a spare, and be happy that I know I won't blow myself up. I like CNG, it does not cook the heck out of everything, as it has lower BTU content than propane, and reportedly is safer. We use our stove an oven a lot when we are on the boat. A propane conversion is the the same as (or more than) a new Roller Furler for me.... Now that's what I'm talkin' about.
As far as getting the parts to make it, I did the hard work, these are all current vendors, the hard part was the Sherex valve. The rest of the stuff you should get locally at your welding supply store and a Hydraulic supply store. I just took my list in, showed them the pictures, and crossed off items as I got them....no big deal.
Fair winds, hope this helps a few people.
Actually I have found sites that sell higher pressure steel tanks for scuba, rated at 3000 PSI. That would be the safe option, plus give you more gas. I know my tank, which was original equipment, is only Hydro'd for 2250, as stamped on the tank. I don't know what the threads are, but they are probably standard. I have "heard" of folks saying the regulator will work up to 3000 PSI on the front end, but I could not find any specifications or markings on it that made me believe that and I am not willing to bet my life on it. I will just fill to 2250, maybe get a spare, and be happy that I know I won't blow myself up.
I like CNG, it does not cook the heck out of everything, as it has lower BTU content than propane, and reportedly is safer. We use our stove an oven a lot when we are on the boat. A propane conversion is the the same as (or more than) a new Roller Furler for me.... Now that's what I'm talkin' about.As far as getting the parts to make it, I did the hard work, these are all current vendors, the hard part was the Sherex valve. The rest of the stuff you should get locally at your welding supply store and a Hydraulic supply store. I just took my list in, showed them the pictures, and crossed off items as I got them....no big deal.
Fair winds, hope this helps a few people.
Regarding CNG systems in boats. As I marine surveyor I have yet to encounter a CNG
system installation (in any boat that I have surveyed) that was rigged in accordance to ABYC standard "A-22 Marine CNG Systems" (i.e. tank secured in place; no non ignition protected devices or internal combustion engine in space containing a tank or contiguous
to such space; tank installed in a vented locker etc. etc.); which means that each of those systems present a fire / explosion hazard.
Suggest; before filling the tank / jury rigging a tank fitting; that you determine that your system conforms to all relevant ABYC standards.
system installation (in any boat that I have surveyed) that was rigged in accordance to ABYC standard "A-22 Marine CNG Systems" (i.e. tank secured in place; no non ignition protected devices or internal combustion engine in space containing a tank or contiguous
to such space; tank installed in a vented locker etc. etc.); which means that each of those systems present a fire / explosion hazard.
Suggest; before filling the tank / jury rigging a tank fitting; that you determine that your system conforms to all relevant ABYC standards.
Seriously?
...in other words, you are failing every vessel you are inspecting, thereby causing the owners expenses of maybe up to several thousand dollars each? Of course you realize, by calling that out you effectively make the vessel not insurable, right? And, who wouldn't go ahead and convert to LPG faced with a major relocation and rebuild, thereby adding hazard? I know, it isn't your problem, you're just applying the standards, etc.
I agree with Rick, conceptually. The only thing our surveyor mentioned was to connect the regulator vent. Our tank is supported, OK re: ignition protection, but a vented locker? Do you have a complete list of requirements?
Please recognize that in numerous discussions on this and other boating forums, the complete ABYC publications seem not to be readily available without a large purchase price.
Please recognize that in numerous discussions on this and other boating forums, the complete ABYC publications seem not to be readily available without a large purchase price.
Not failing the vessel just accurately describing its condition (based on accepted standards & practices) at time of survey. Just think what it would be like if one failed to note a deficient situation (not to mention a fire / explosion hazard) and a property damage / injury / loss of life event was caused by a "not important" defect. (Suggest you posit your position to your boat insurance underwriter for their thoughts.)...in other words, you are failing every vessel you are inspecting, thereby causing the owners expenses of maybe up to several thousand dollars each? Of course you realize, by calling that out you effectively make the vessel not insurable, right? And, who wouldn't go ahead and convert to LPG faced with a major relocation and rebuild, thereby adding hazard? I know, it isn't your problem, you're just applying the standards, etc.
To give an idea as to the complexity of a marine survey ABYC standard A-22 as a pdf is attached.
Thanks for that.
It starts off by stating:
ABYC recommends compliance with this standard for all systems manufactured or installed after July 2013.
Could you comment on systems installed before that date? I know from building codes that grandfathering is reasonable, and that making older buildings comply with new codes & standards isn't normally done.
Is the same true for boats?
I also recognize that "doing it right and safely" is also important.
I'm in the process of reading it now, thanks again.
For example:
EXCEPTIONS:
1. Accommodation spaces.
2. Open compartments having at least 15 in2 (97 cm2) of open...
We have two cylinders, one's in use, the other is a backup. Both fit under this exception based on where they are located and the spaces' ventilation (open ports and dorade vents).
Dedicated sealed lockers are also not required for small CNG single tanks the way I read it.
The thing I'm getting to, in parallel with Rick, is that if a surveyor reads and ticks off these "deficiencies" they simply MAY NOT APPLY to the boat being surveyed.
If a surveyor did that to me, I'd be hopping mad, 'cuz it means he didn't read the regs as they apply to MY boat.
Comments?
Fortunately the actuarial odds usually are in our favor (until there not).Discussions with insurance underwriters (regarding recent surveys) indicated that they do not
"grandfather" systems like CNG or LPG. There is no pleasure in delivering negative survey findings.
Dedicated locker is required when tank capacity is >100cu ft. There are separate standards for devices using cylinders <16oz.
22.7.4.7 For CNG installations that include an attached combined capacity of greater than 100 cubic feet (2.8 cubic meters), the cylinders, and connected valves, regulating equipment, and safety devices shall be located on the exterior of the boat where escaping gases can flow directly into the atmosphere outside the boat, or
22.7.4.7.1 the cylinders and connected devices shall be installed in a dedicated locker.
22.7.4.7.1.1 Dedicated lockers shall be vapor tight to the hull interior, and
22.7.4.7.1.1.1 vented to the open atmosphere outside the boat, and
22.7.4.7.1.1.2 constructed of or lined with corrosion resistant materials, and
22.7.4.7.1.1.3 equipped with a means to discharge incidental accumulated water.
22.7.4.7.1.2 Dedicated lockers shall be equipped with a cover that
22.7.4.7.1.2.1 opens directly to the atmosphere, and
22.7.4.7.1.2.2 latches tightly, and
22.7.4.7.1.2.3 is capable of being quickly and conveniently opened without tools, and for operating the cylinder valves, testing the system for leakage, and viewing the pressure gauge.
I provide my survey clients with the text of the ABYC standard relevant to the survey discovered deficiency.
FYI ABYC membership starts now at $255.00 per year.