Rotopax - Is there something better I should be using?

[Keith Starr]

I ditched my four 2-gallon Rotopax after heat caused too much frustration:

• They swelled up in the mounts making them extremely difficult to screw off
• Once off the mounts the Rotopax tended to retain the new balloon shape making them difficult to reinstall

They look really cool and are a good idea in theory but in my experience the Wavian can is so much easier to use. I've since switched to two 20L Wavian cans and mounts. Not having anything to unscrew when dealing with refueling makes everything painless.

Wavian: https://wavianusa.com/products/steel-fuel-jerry-can
Mounts: https://wavianusa.com/collections/accessories/products/steel-fuel-can-holder?variant=18232152653891

To top it off I use a "Super Jiggler" so I don't even have to hold the fuel can when refueling, just a couple...uh...jiggle motions and science does the work.

 

[pluton]

In case anyone is interested, the European-made 20L Jerrycans seem to have dropped in price at Deutsch Optik...competition, perhaps. Now cost less than when I got mine about 5 years ago. The least leaky gas cans I've ever used.
https://deutscheoptik.com/20-Liter-Jerry-Can-SINGLE-CAN.html

 

[rnArmy]

In case anyone is interested, the European-made 20L Jerrycans seem to have dropped in price at Deutsch Optik...competition, perhaps. Now cost less than when I got mine about 5 years ago. The least leaky gas cans I've ever used.
https://deutscheoptik.com/20-Liter-Jerry-Can-SINGLE-CAN.html

That's where I get my Jerry cans - Deutscheoptik.com They're good quality. I wish they still carried the 10L (2.5 gallon) cans.

 

[TrailWhalePowerwagon]

for south florida with extreme heat, in the bed of the black truck, im concerned about the venting and swelling. not sure if the scepter cans are ideal, or if i really need to get Civ cans with vents

 

[JPaul]

That's where I get my Jerry cans - Deutscheoptik.com They're good quality. I wish they still carried the 10L cans.

Atlantic British www.roverparts.com carries the half height style 10 liter cans like the one you have. 4 pack of the 20 liter cans is $170 plus shipping. I know the DO cans are available for less, but after buying a set of cans from Atlantic British and then getting a set from DO, I prefer the ones from Atlantic British. The locking pins actually lock and they only have a sticker on them saying not for fuel whereas the DO actually has it embossed into the side of the can. They appear to be the same otherwise but I'm concerned the DO cans are possibly lower quality, they definitely don't appear to come from the same manufacturer.

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[JPaul]

for south florida with extreme heat, in the bed of the black truck, im concerned about the venting and swelling. not sure if the scepter cans are ideal, or if i really need to get Civ cans with vents

What I find interesting is that I'm fairly sure that really anything that is liquid is in that state due to the pressure it is under, it's just that some compounds liquidate at much lower pressures than others. Gasoline stays liquid at a certain temperature and pressure, but when the temperature rises it turns into vapor/gas more readily. The plastic cans permit the pressure to stay lower due to their flexibility so they end up swelling as more of the gasoline turns to vapor. Steel cans though keep their shape better and can keep the pressure high enough that not so much of the gasoline turns into vapor as temperature rises. This is all just my theory though, but personally I much prefer steel cans over any plastic can. Maybe if we could get the military plastic cans easily here I'd be more inclined towards those.

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[krick3tt]

Same expansion happens when I climb in altitude in CO and the sun beating on my Nato cans on the roof rack. Have to be careful when I open them so the opening isn't toward me. But, still they do not leak. My Sceptor cans do.
edit: conversely if I open them at altitude and then go lower or it gets colder they compress the sides. still no leaks.

 

[luckyjoe]

You'll not find better than the NATO cans from AB. Durable, easy to carry and store, and I have never had one leak. If you live in an area where they enforce CARB-compliance, get the Wavian CARB nozzle only (several sources sell them separately). This nozzle is great at fuelling small engines at first, then becomes terrible as it will begin to stick after exposure to fuel (yes, that's true). But at least you'll be compliant if questioned at the pumps.

 

[outback97]

Gasoline has about 5X the volumetric thermal expansion as compared to water, plus a lot of vapor pressure, so yeah they're going to swell up if you don't vent them.

If I had a good way to mount a NATO can, I'd maybe use that, but I like the low profile form factor of the Rotopax and I got a good deal on them, so I use those.

One thing I have learned to do with the Rotopax is to acclimate them before a trip so they don't swell so much when parked in the sun. After filling it up with cool gasoline, I'll set the can in the sun to warm it up and vent a few times so it doesn't get too swollen and distended sitting in the sun on the roof.

If you tighten the cap enough to avoid leaks, I have found that I sometimes needed to use a channel lock pliers to help remove it. Then I found this 3D printed cap wrench and a friend of mine printed it up for me. Pretty handy!

https://www.thingiverse.com/thing:3122299

 

[verdesard0g]

I doesn't matter how much you pre-vent a gasoline container, it will build up to the vapor pressure determined by the current temperature.

 

[verdesard0g]

I'm using surplus Nato secepter cans for diesel in my truck. so far no problems!

 

[outback97]

I doesn't matter how much you pre-vent a gasoline container, it will build up to the vapor pressure determined by the current temperature.

Yes, you'll always have some vapor pressure. What I'm talking about is, with a nearly full Rotopax, capping it tightly only after the liquid has expanded from warming up. This helps reduce the bloated, distended sides of the can problem.

In a 2 GL size, warming the gasoline from 55F to 105F expands it by almost half a pint of liquid volume. That's quite a lot, and that essentially incompressible fluid volume increase exerts a lot of pressure on the sides of the Rotopax.

Could be I'm not explaining it well, could be that I don't know what I'm talking about. My experience is that it works for me and keeps my fuel cans from becoming distended, so I'll continue to do it this way.

It does mean that when you travel somewhere that's lower elevation and colder, the Rotopax will flex inwards a bit. Doesn't seem to hurt it though.

 

[Lucky j]

I have just saw this pic and just fou d out a few days ago that it is illegal to carry a propane cylinder on tye roof of a vehicule in the Province of Quebec, and probably in Canada as well (this would have to ne confirmed).

Wonder what it is in the US. Of A and in the US of M??

Bought the mounting plate and attached it to the Front Runner rack a few years ago.

Add a couple extensions and it holds 8 gallons.

I've never had a problem with the locks but usually don't leave them up there unless it's a long trip.

But maybe that's because we live in a desert. Anyway, here's how I arranged things a while back.

 

[dreadlocks]

ANSI A119.2/NFPA 1192 STANDARD ON RECREATIONAL VEHICLES (1999 Edition)

2-2.3 Location of LP-Gas Containers. LP-Gas containers shall be in accordance with the following:

(a) LP-Gas containers shall not be installed nor shall provisions be made for installing or storing any LP-Gas containers, even temporarily, inside any recreational vehicle. Containers shall not be mounted on the exterior of the rear wall or the rear bumper of the vehicle.

Exception: New LP-Gas cylinders that have never contained LP-Gas supplied as original equipment, shall be permitted to be transported inside the vehicle.

(b) LP-Gas containers with their control valves shall be installed in compliance with one of the following:
(1) In a recess or compartment other than the roof that is vaportight to the inside of the recreational vehicle.
(3) Tanks mounted on the chassis or to the floor of a motor home or chassis-mount camper, provided neither the tank or its support is located in front of the front axle. Tanks mounted between the front and rear axle shall be installed with as much road clearance as practical but not lower than the front axle height. Tanks mounted behind the rear axle of a motor home or chassis-mount camper shall be installed in such a manner that the bottom of the tank and any connection thereto shall not be lower than either the rear axle (excluding the differential) or any section of the frame immediately to the rear of the tank, whichever is higher. All clearances shall be determined from the bottom of the tank or from the lowest fitting, support, or attachment on the tank or tank housing, which ever is lower when all axles are loaded to their gross axles weight rating.

emphasis added, however these regulations are mostly regarding the installation of a LP tank.. not the transportation of it as illustrated above... enforcement of these is non existent, you see ppl carrying tanks on rear of vehicles all the time.

 

[WeekendWannabe]

I picked Jerry cans - https://deutscheoptik.com/20-Liter-Jerry-Can-SET-OF-FOUR.html

At the time, it was the most fuel I could store per dollar spent on containers. I've also seen Rotopax on the roof soak up a lot of sun and swell up to the point they couldn't be removed, the owner had to open them on the roof to relieve the pressure (that was... messy).

I like rotopax, but I just think they are expensive for how much you can carry. I would certainly use them for smaller applications, like a motorcycle.