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DaveD (142.46.196.34)

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Posted on Tuesday, June 17, 2003 - 1:04 pm:   

So far we are operating our coach as all electric, but it contains appliances that will run on either elctricity or propane fuel.

I've noticed that manufactured RVs such as 5th wheel trailers leave the bottom of the tank compartment completely opento the road. I'm using two portable propane tanks and am thinking of cutting a rectangular opening in the floor of the bay where they are to be installed, equal to the dimensions of the bottom of the tank enclosure. Will an opening of this size affect the structural integrity of the bus (MCI MC-8)?

Dave Dulmage
(MC-8)
Dale MC8 (66.81.130.242)

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Posted on Tuesday, June 17, 2003 - 3:04 pm:   

Dave, the answer to your question is outside my knowledge. What is not is the reason the manufactured RV's leave the bottom of the tank compartment open. Its easier to make and cheaper. That much vent space is WAY more than needed. Something to think about.
Dale MC8
Quest (198.29.191.148)

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Posted on Tuesday, June 17, 2003 - 4:40 pm:   

I have to dissagree with you, you need to keep that area ventilated as much as possible. the propane is stored at about 200# psi and if it gets a chance to expand all of a sudden and you have a piddly hole cut in the box, the propane will expand into the coach, all it needs then is a spark, and you will be buying a new coach, if you survive the blast. q
Quest (198.29.191.148)

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Posted on Tuesday, June 17, 2003 - 4:47 pm:   

Found this on the other board posted by CoryDane and Walt (I thnk)
=============================================

Posted by CoryDane(RTSII)IL on May 24, 19103 at 08:08:45 PST:
In Reply to: Re: Mounting / Walls posted by JimNH on May 23, 19103 at 16:18:29 PST:

I enjoy the use of propane appliances so it is imperitive to keep the storage of this gas completely safe.
I agree with your idea to take the bottome out of the bay and install screening. I have never agreed with the cutting of a couple of holes to vent idea for the following reasons.
1 for minor, tiny leaks, that is, NO PRESSURE leaks, the vent hole might be alright, the small amount of gas may just go out the hole and vent the area clear but this is no answer to a pressure leak.
2 in the case of a hi pressure hose leak or tank rupture, a hole cutout is no match for the massive amount of pressure that will occur, you WILL get gas in the cabin, and if you have any sparks or flames, you WILL destroy your bus.
for this reason I beleive in giveing the propane tank all the room it needs to get rid of any gas that may escape from the system and using the entire floor space under the tank is a really good idea. As for sharing the compartment with water tanks, space wise it is a good idea, however if you have a light in the water compartment, it could cause a spark, then the old scenario comes to light again.
I would suggest that useing the same bay is ok but I would put up a wall to keep the gas inthe propane bay so it can effectively ventilate on its own. REMEMBER, propane is a lazy, slow moving gas, it likes to find corners and puddle and it doesnt ventilate on its own so it would tend to stay by your tanks or whatever else is in there. It would take a long time for the gas ventilate the storage area on its own and again, it only takes a spark.
A lot of people like to do things "THEIR WAY" in this hobby but in the case of propane, you need to go as SAFE as possible, that includes running lines in ventilated areas where ever possible, especially where there are connections for accessories.
This is what I have come up with after studying many motorhomes and some propane storage systems. Now some mention that boats store in a compartment, and this is true, but they are designed for specific use, are top deck, protect the tanks from elements and I think they are designed for the hi pressure release of a tank failure. I do not believe, in any stretch of the imagination, that a bus compartment can be built to mirror those same design standards.
Hope this was food for thought, good luck -= cd


: CoryDane: excelent points but...
: !!! "in the case of a hi pressure hose leak..."!!! NEVER EVER have a high pressure line! Mount the regulator directly to the tank and have only low pressure lines. If you have more than one tank, ose a seperate regulator on each one. Regulators are dirt cheap!
: The tank fittings (all of them) must be protected from impact, including the tank mounted regulator.
:
: : I enjoy the use of propane appliances so it is imperitive to keep the storage of this gas completely safe.
: : I agree with your idea to take the bottome out of the bay and install screening. I have never agreed with the cutting of a couple of holes to vent idea for the following reasons.
: : 1 for minor, tiny leaks, that is, NO PRESSURE leaks, the vent hole might be alright, the small amount of gas may just go out the hole and vent the area clear but this is no answer to a pressure leak.
: : 2 in the case of a hi pressure hose leak or tank rupture, a hole cutout is no match for the massive amount of pressure that will occur, you WILL get gas in the cabin, and if you have any sparks or flames, you WILL destroy your bus.
: : for this reason I beleive in giveing the propane tank all the room it needs to get rid of any gas that may escape from the system and using the entire floor space under the tank is a really good idea. As for sharing the compartment with water tanks, space wise it is a good idea, however if you have a light in the water compartment, it could cause a spark, then the old scenario comes to light again.
: : I would suggest that useing the same bay is ok but I would put up a wall to keep the gas inthe propane bay so it can effectively ventilate on its own. REMEMBER, propane is a lazy, slow moving gas, it likes to find corners and puddle and it doesnt ventilate on its own so it would tend to stay by your tanks or whatever else is in there. It would take a long time for the gas ventilate the storage area on its own and again, it only takes a spark.
: : A lot of people like to do things "THEIR WAY" in this hobby but in the case of propane, you need to go as SAFE as possible, that includes running lines in ventilated areas where ever possible, especially where there are connections for accessories.
: : This is what I have come up with after studying many motorhomes and some propane storage systems. Now some mention that boats store in a compartment, and this is true, but they are designed for specific use, are top deck, protect the tanks from elements and I think they are designed for the hi pressure release of a tank failure. I do not believe, in any stretch of the imagination, that a bus compartment can be built to mirror those same design standards.
Ross Carlisle (Ross) (216.107.195.132)

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Posted on Tuesday, June 17, 2003 - 5:05 pm:   

The reason they ventilate through the floor is that propane is heavier than air. Any vent in a propane bay must be as low as possible. Venting in the floor is the best way to ventilate any propane leakage. I put my propane tanks in the bay used to house the AC condenser. Plenty of ventilation there.

If you look up the code for venting propane, it will suggest specific vent size openings and placement relative to the floor.

Ross
C Fred (69.19.130.57)

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Posted on Tuesday, June 17, 2003 - 5:58 pm:   

I just came back from a RV salvage yard. I was there to buy a few things. And of the 100 plus coaches they have most have burned. And a lot have had propane fires. That is why I have only electric coaches of my own.C Fred
two dogs (66.90.211.166)

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Posted on Tuesday, June 17, 2003 - 6:07 pm:   

I SAY..the cargo floor IS very structural..and don't cut a big hole in it..get ya' a new 3/8 drill bit,& a nice slow 1/2 drill & drill about 100 holes about 2" apart in the floor..you will loose no strength AND have the ventalation...
john marbury (Jmarbury) (65.100.118.132)

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Posted on Tuesday, June 17, 2003 - 8:42 pm:   

You say alot have been propane fires but haven't alot been electrical fires as well? Just wondering.
John
Ross Carlisle (Ross) (216.107.195.198)

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Posted on Tuesday, June 17, 2003 - 10:13 pm:   

Seems like every time I see a burned out RV on eBay, it's an electrical fire.

Ross
Jack Conrad (Jackconrad) (204.193.117.66)

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Posted on Wednesday, June 18, 2003 - 9:55 am:   

Per Code, LP compartment is to be vented with 1 sq. inch of vent per 7 lbs. of propane. With part of this vent at the top of the compartment and the rest of the bottom, preferably in the floor. This means roughly 3 sq. inches per 20# tank. as was already mentioned LP is heavier then air and will settle to the low spots and tend to stay there until forcefully removed with air flow or a spark. Hope this helps, Jack
CoryDaneRTSIIIL (4.17.253.46)

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Posted on Wednesday, June 18, 2003 - 12:20 pm:   

Thanks for bringing my comments up again. And to the comment of the compartment floor being structural, Eeegads! Lucky for US who have the RTSII where there is no floor in the compartment areas for we have no worries of cutting structure there. Iwill never lose the message that irregardless of what the book may say, YOU GOT TO LET THE GAS VENTILATE. A couple small holes may be well suited for a proper fuctioning system but as said before, when you have a pressure leak, you got big troubles and it will seep where ever it can, and that means inside your coach, LOOKOUT, there goes another bus up in flames.
It is great you are doing your home work and I believe in going way above and beyound the standards when it comes to safety. Read what the book says then DOUBLE the recommended standard. Personally, I would not put a floor in the PROPANE compartment just because of the charactoristics of the gas. If you don't know the charactoristics, you need to learn before you build the compartment. Propanes is great for our use, you must, however, build in for your safety to keep it that way. cd
Gary Stadler (Boogiethecat) (68.7.217.217)

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Posted on Wednesday, June 18, 2003 - 12:21 pm:   

...and don't forget that you "should" pipe the pressure relief valve of any mounted propane tank all the way to the back of the bus, up and out. Most people miss this fact...
I'll keep harping on this one. Tanks do vent and surprisingly more often than you'd think, usually due to fools stuffing the tanks (HOW many times do you see the fill operator see the pee valve indicate "full", then take it to the next gallon before stopping the fill!!), excessively hot days and hot roads, etc... Having propane venting under or otherwise near your bus is not a good idea... those vent valves have threads for a reason...
Peter Broadribb (Madbrit) (208.186.36.187)

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Posted on Wednesday, June 18, 2003 - 1:07 pm:   

Happened to us, we had the tank plus 2 BBQ tanks filled locally and even after a weekend away,the pressure valve blew-off whilst driving home.

It was a very loud noise, I thought we'd got a blown tire it was so loud. Pulled over and then smelled the propane.

The following day I tried to lower the level by opening the "pee" valve, but it was making no effect on the level gauge. So I made sure the motorhome was well away from the house, etc and removed the main supply pipe and opened the valve. I had to leave it for nearly 10 minutes to get it down from a pegged 100% to the recommended max of 80%.

Just a little overfilled do you think? It amazed me that it took so long to blow-off the valve and whilst driving too.

Peter.
Chuck Harris - PD4104 (207.172.11.147)

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Posted on Wednesday, June 18, 2003 - 2:14 pm:   

Here's one thing I never see mentioned about propane: The connection between the tank and the first regulator should be the tiniest little 1/8" OD copper tube. This is called a "pigtail" and they are readily available from your propane service supplier.

This tiny little 1/8" OD tube is big enough to feed the regulator with about a 1/2 million BTUs! So really even it is way too big for an RV.

The idea here is to limit how fast the propane can blow out of your tank if the regulator should fail and start to vent.

-Chuck
Gary Stadler (Boogiethecat) (68.7.217.217)

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Posted on Wednesday, June 18, 2003 - 8:12 pm:   

...and actually in a mobile rig, that pigtail would be a lot better off if made with stainless-braided hose that is manufactured specifically for propane. NOT the high pressure stuff for BBQ's that a lot of propane dealers will try to sell you, because it's braided but not with stainless steel- instead it's a fiber braid and not a good item for an RV.

The advantage with braided stainless lines of any kind, besides simply being strong, is that they are also VERY abraision resistant. Case in point, a friend of mine once asked me to help him figure out why his clutch had failed in his front-wheel drive car. I took a look and immediately asked him how long ago he'd replaced his brake lines to the front wheels...the reason I asked is because it wasn't the clutch... whoever installed the brake lines let the right hand one rub on the front axle. The rubber on the brake line was gone at that spot but the stainless braid was untouched and had abraded the axle clean into two pieces.... And it took only three months to wear it all the way through!!

Back to the point... Solid copper pigtails can work harden from vibration and may break... they are mostly designed to be used on fixed household tanks that don't wiggle. But I agree, whatever that line is made of should be small and as short as possible. No high pressure lines belong in RV's if you can help it.

That said, when you do a propane powered engine, the lines between the tank and the evaporator are braided stainless, long, and liquid... they are at tank pressure. Installed properly they are as safe as anything...

Cheers
Gary
DaveD (216.133.188.162)

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Posted on Sunday, June 22, 2003 - 7:37 pm:   

Thanks for all the good information.

Dave D

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