CNG/LPG gas hose

SVPardonMyFrench

SVPardonMyFrench

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Dec 31, 2011
191
Hunter 40.5 Seattle
I am in the process of converting from CNG to LPG and trying to trace the hose that runs from the tank in the port lazarette to the stove. Before I remove all the floorboards etc... thought I would ask if someone had any insights?

thanks much!
Frederick
 
SVPardonMyFrench

SVPardonMyFrench

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Dec 31, 2011
191
Hunter 40.5 Seattle
Found it for those of you might be looking for it.. It's goes under the bed, into a white protection hose under the port locker to the stove.
 
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jssailem

jssailem

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Oct 22, 2014
21,098
CAL 35 Cruiser #21 moored EVERETT WA
Where in the area are you sourcing your new hose?
 
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smokey73

smokey73

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Oct 26, 2010
1,903
Hunter 40.5 Beaufort, SC
mistralseattle said:
Found it for those of you might be looking for it.. It's goes under the bed, into a white protection hose under the port locker to the stove.
Click to expand
Why are you needing to replace the hose? I was under the impression that the same hose could be used but i'm sure there is a reason it may need to be done. Also I am considering the conversion and I'd be interested in your details including the converison kit for the burners in your stove/oven (or if you are getting a new stove/oven), the LPG locker you are going to use, the size of tank and basically all the plans. It would be a real help. A PM on your plans would be greatly appreciated.
 
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1mcarlson

1mcarlson

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May 23, 2013
54
Hunter H42 Passage East Chicago and Hammond
Yes dying to know the why and how. Wanting to sail Caribbean and wondering on the natural gas stove if I should change over.
 
jssailem

jssailem

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Oct 22, 2014
21,098
CAL 35 Cruiser #21 moored EVERETT WA
@smokey73 and @1mcarlson
Here is the info from ABYC on the hose requirements for LPG. There are different sized orifices used to provide the gas to the stove. You will need to research this.
A-1.9 FUEL LINES
A-1.9.1 As installed, the fuel supply line system and its components shall be compatible with LPG, and
shall withstand the stresses and exposure of the marine environment.
A-1.9.2 LPG fuel supply line shall comply with the construction, performance, manufacturing and test, and
marking requirements of UL 21, LP Gas Hose, or
A-1.9.2.1 be corrosion resistant metallic tubing such as annealed copper tubing, standard type, Grade K or L, conforming to ASTM B88-75a, Specifications for Seamless Copper Water Tube, with a wall thickness of not less than 0.032 inches (0.815 mm).​
I've attached the ABYC document for your review.
Good luck.
 

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J

JimInPB

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Aug 22, 2017
1,609
Hunter 26.5 West Palm Beach
+1 on orifice sizes being different. The ratio of gas to air is different for the different fuel gasses. Changing the orifice is how you get the mix right. The orifice is usually a small brass piece that either screws in or is brazed in somewhere near the air intake on the mixing gizmo.

As for the hose itself, I am not sure if it needs to be changed or not. It is my understanding that CNG operates at MUCH higher pressures than LPG, so if you were going from LPG to CNG, a hose change would almost certainly be needed. Going from CNG to LPG, unless there is some chemical incompatibility, I am not sure that you can't use the old hose. I don't know for sure that you can use the old hose, but I'm curious if you might be able to.
 
jssailem

jssailem

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Oct 22, 2014
21,098
CAL 35 Cruiser #21 moored EVERETT WA
The hoses I reviewed for CNG looked great, then there was the notice, "Not for interior use like on a vessel or RV". There were discussions about use of water hoses but also not an approved hose for use.
Maybe need to visit a Propane dealer to get clarity.
 
Gunni

Gunni

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Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
While CNG tank pressures are very high compared to a LPG tank pressure, they both regulate down to a low pressure going to the appliance. Can't see any reason to change the hoses. LPG has LOTS more energy per unit of gas so you have to lean down the burner with a new orifice. New tank regulator, new burners and a tank storage locker that vents heavier-than-air LPG from the bottom. Natural gas is lighter than air and will vent out the top of the storage locker.
 
SVPardonMyFrench

SVPardonMyFrench

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Dec 31, 2011
191
Hunter 40.5 Seattle
Thanks for all the comments.

I had to change to LPG since it was becoming quite impossible to find CNG in the Seattle area. Shishole stopped the exchange program a little while ago and suremarine their supplier is getting out of this business.

The entire CNG set-up was original and over 20 years old, and the cost of new hose is minimal and a fresh end-to-end install meets all ABYC norms which will come in handy when I sell the boat. I am also changing the stove after 20+ years of use. All new stoves are equipped with thermo-couplers that prevent gas from running if the flame goes off -- that was another reason for me to upgrade.

Here are few pics for the upgrade (Stove coming soon)
 

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smokey73

smokey73

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Oct 26, 2010
1,903
Hunter 40.5 Beaufort, SC
Where did you purchase the propane locker and what size is the propane tank?

Did the stove and oven fit in the original spot with no modification? What model?

Where did you install the propane detector and shutoff?

Same problem here on mcg availability and am considering the mod.
 
jssailem

jssailem

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Oct 22, 2014
21,098
CAL 35 Cruiser #21 moored EVERETT WA
@mistralseattle thanks for the insight.

I am looking for a store to buy the hose. Did you buy the hose in Seattle?

Fisheries did not have a premade length that fits. So I need to make my own.
 
SVPardonMyFrench

SVPardonMyFrench

.
Dec 31, 2011
191
Hunter 40.5 Seattle
Yes got all for suremarine. Also they were competitive on price with fisheries (my usual go-to with defender). This is what sure marine specialize in. Btw baked two pizza with the new stove this weekend. Very happy with the set-up. Here a pic of the stove (force10 3 burners)
jssailem said:
Nice refit @mistralseattle . Where did you get the hose for the tank to stove run?
Click to expand
thanks! Suremarine in Seattle
 
smokey73

smokey73

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Oct 26, 2010
1,903
Hunter 40.5 Beaufort, SC
smokey73 said:
Where did you purchase the propane locker and what size is the propane tank?

Did the stove and oven fit in the original spot with no modification? What model?

Where did you install the propane detector and shutoff?

Same problem here on mcg availability and am considering the mod.
Click to expand
Mistralseattle, I'm not sure you say my request so was hoping for some details. I got where you purchased the hose. Just wondering on the other items. Thanks and I hope you can provide this info. You can PM me if you would rather do that
 
SVPardonMyFrench

SVPardonMyFrench

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Dec 31, 2011
191
Hunter 40.5 Seattle
All done with the conversion. Here's the pic of the new stove. Baked two pizzas (at once!) this weekend to feed a hungry crew. Very happy with the set-up. All parts came from SureMarine in Seattle, except for tank that comes from West Marine (only ones who had it in stock) Sure Marine specializes in gas/stove etc and had most parts handy-- and were competitive with my usual go-to stores (fisheries and defender). Needless to say that I am thrilled that I can get gas around pretty anywhere I want now
 

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smokey73

smokey73

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Oct 26, 2010
1,903
Hunter 40.5 Beaufort, SC
Mistralseattle, Thanks, is there a specific "conversion kit" for the propane locker that you used? Do you happen to have the model/part number or do I just go to Sure Marine and tell them I have a Hunter 40.5 and they take it from there.

Were you able to use the existing overboard vent that is installed for the CNG on the Hunter 40.5. It seems a little to high to allow a constant downward vent path for the LPG?

Inquiring minds want to know? Thanks in advance. You can responde in a PM if you like to avoid cluttering the general forum with this type of info. Were you able
 
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