Gasoline versus Kerosene - Optimus Nova

The MSR pump has a synthetic rubber cup, not an o-ring. It is compatible with a leather cup, if you wish to put up with fitting it.

If possible, I like to fit the leather bucket backwards, then refit it after it has set to the pump tube. Not possible with the MSR pumps, but often with metal pumps. The other option is using a thin firm plastic sheet (from old takeaway container?) to make a cone at the mouth of the pump, push the leather cup just in and then withdraw the plastic while pushing the plunger in.

 

Hi,

Thanks for that information. I seem to remember now seeing a picture of the cup in the Dragonfly pump but had forgotten.

The synthetic rubber cup in the Dragonfly...does that cause issues also? It does seem to provide a great seal. I've requested another leather cup from ozbackcountry where I bought the Nova and sent a picture. I get it, that it can be resurrected...maybe if you are familiar with them.

What about lubrication? How important is it? I wonder if I might have damaged the leather cup when I did take it out to lubricate it. I thought I was being careful to make sure that the edges didn't get caught. It still doesn't seem like a great design as I can see it being easy to damage the leather cup.

Others on the forum are well familiar with this issue, it seems. The question should be...how often does this type of thing require a replacement leather cup even for knowledgeable people such as yourselves? I will leave it for the time being but keep the old cup and also see if I get a replacement cup which will take a few weeks in the post even if they can get them.

 

I find it contradictory to think outside reviews give better information than this forum as a whole.

 

I think it’s unlikely the leather cup was damaged simply by you removing it from the stove — likely the “nick” was already present. If just in the edge of the cup, it might have been repaired with some judicious trimming.

Problems arise when one tries to force a too-large leather cup into a pump, and this may? be what happened here. I’m also wondering if the reviewer’s leather cup was properly lubricated (soaked in oil for several hours if it had completely dried out).

Spares (o-rings and leather cups) can dry out in your spares kit, as well as in your stove. On a long backcountry/mountaineering trip, I would much rather do maintenance on a leather cup before each use (if that was really necessary), than to replace a broken o-ring with my spare and wonder if the spare would survive for the remainder of the trip.

….Arch

 

Hi Arch,

I tried to attach an image link from Onedrive of the cup. (Edit: pic uploaded to the site. See below)
I appreciate your help and from others also, nice forum.

I haven't done any more with the old cup but today I lubricated the new cup with the supplied lube and put it back in. It did make a big difference and the pump now works as well as the MSR and can build up as much pressure as needed to the point it is hard to add another stroke.

I tried some toast on the Nova burning kerosene and it was amazingly hot and did the toast in record time. I think I have been losing pumping slowly for days or longer until I had a serious problem that simple lubrication didn't fix.

The MSR by the way on petrol does not do toast well as is the case on the Nova on petrol also, it just doesn't produce enough heat. I have tested boiling times and it tells me the same thing, kerosene just produces more energy and it is mainly do to the mass flow rate which is greater with kerosene. It tells me that their boiling time estimates are based on the energy value of the fuel, not the mass flow rate which depends on specific gravity or density.

I just used the lubricant supplied with the pump. I also have a large tube of silicone food grade lubricant as well, that should be OK to use? I don't even know what is in their white grease. Any suggestions appreciated.

Cheers,
Grant

 

I'm a newb, a grommet, compared to many here, so take this with a grain of salt, but...

That old pump leather looks inside-out to me.

Shouldn't the grain be on the outer?

 

There is a finished and unfinished side and the old and new cup had the unfinished side facing outside. I think that this is correct and I did try reversing it at one point yesterday and it made it worse. I tried a few things but the new leather cup after a bit more lube is working as well as the new MSR Dragonfly pump.

 

That's not the best cup I've ever seen, but I've seen and used worse. It looks pretty dry to me -- might just be the lighting, but I would be tempted to soak it in mineral oil (or any oil, really; I've used olive) and massage it and see if it improves. I usually prefer silicone grease for o-rings and other rubber seals. And, as I stated, I prefer leather for the moving cup, rather than an o-ring. Much as you try not to, you can get dust in the pump tube, and the leather is just going to be more robust in that environment. I have had o-rings fail on trips -- I think it's more because of the cold than anything else, and I've always had a spare o-ring to replace the broken (or in one case shredded) one, and I'd just rather not worry about the pump cup doing that.

....Arch

 

Hi Arch:

I will definitely keep the old one...the new one is working really well so I will keep that in there. I have contacted the company I bought it from. I think given it is only a few weeks old, although used quite a lot in that time, they should replace it. I can see why some people get these stoves then immediately strip them down and check and lubricate everything. I just assume all is well from the factory. The pump is a part that gets used a lot so I just need to lubricate this more regularly.

The Nova is an excellent stove. I don't really want to lose confidence in using it so your advice and help is much appreciated. I'm back to using the Nova. My preference is always kerosene if I need heat and I'm starting to prefer priming with alcohol even when I use petrol.

Cheers,
Grant

 

The Dragonfly does continue to drip fuel after turning off the burner using the bottle valve. Just a small amount that doesn't burn out.

I tried unsuccessfully the first time to rotate the bottle (when it was full to the line) to turn it off and depressurise the bottle which it wouldn't do, unlike on the Nova. Now I have used some fuel this trick does work.

I think the residual fuel in the line is not a good thing and I can see why Optimus and Primus make this a main feature of their stove and make it work. Residual fuel stinks one way or another whether removing the burner for transport and it means the burner and bottle can't be put inside anywhere as a unit when not in use due to the odour and risk of a ignition in a confined space.

I love the Dragonfly the way the burn and flame is so very stable and predictable. It is too on the Nova, very good, but you can get some surging sometimes but so far haven't seen it happen on the Dragonfly...at all.

I haven't tried kerosene yet but I might do that on the weekend. If I take my stove camping this weekend though it will be the Nova until I get to know the Dragonfly better.

Does or has anyone owned both of these stoves? I'm sure that the compromise on the single jet for the Nova does carry some cost and I am probably looking at it. I think also the Nova has the recommendation to use kerosene but white gas or petrol is recommended for the Dragonfly. The manufacturers may compromise on one fuel or the other and I don't think performance is solely related to the jet. The heat sink of these two stoves is VERY different. The heatsink on the Nova is bigger and distributed in fins rising above the jet whereas the DF has the heat sink at the base. I like the base design on the DF better even though it is bigger. The burner can not leak fuel onto the ground whereas you can on the Nova, the DF is sealed at the bottom. I think that the support design on the DF is very nice and better even if bigger than the Nova. The leather cup...not sold on that but I get it and it does work well now on the Nova and I have been generous with the supplied lubricant. I will do some more checks on the DF today and do some lubrication rather than make assumptions as I did with the Nova.

 

Ahh. Just tried the DK jet for kero in the Dragonfly...interesting...same heat output as on gasoline with the DG jet.

This is unlike on the Nova where the same jet is used and results in a much higher heat output on kerosene.

I suppose it makes sense...same orifice...similar volumetric throughput.

I like having the option for a higher heat on Kero on the Nova even though I know you can use kerosene using the DG jet on the Dragonfly but that is a compromise as well.

 

Far out...I should do another thread on this Dragonfly. Now it is blocking...first time there was some crud after changing the jet back to gasoline and I unblocked it. It then started to run average so this time had a better look and lots of brown crud flakes down below jet in burner so ran a bit of fuel through. Still not happy so will do again tomorrow.

 

The main advantage of expedition stoves is that you can clean them. The main trouble is that you have to. The issue is always* the fuel leaving residues so it's not really a fault of the stove.

* other than the first clean from new when some stoves have had swarf.

 

It’s generally accepted around here that running any stove on petrol will result in significantly more blockages than kerosene or white gas / shellite. This is because of the additives for engines that don’t burn properly at stove operating temperatures.

Petrol is ok if that’s all that is available but the blockages are painful so make it a last resort. Also, you end up breathing in those unburnt additives.. The orange flame tips are showing you they are not burning properly.

The cost of shellite / brake cleaner / panel wipe here in the land of oz makes kero the default choice in my mind for an expedition stove. But I don’t enjoy stove maintenance / reliability risk at all and don’t need to melt snow so have switched to 100% alcohol stoves instead.

 

Well those small jets don't take too much to block that is for sure. The only real issue would be if the jet were damaged beyond repair else it is easy enough to clear these. I have my Nova probably running mostly now on kerosene. It is funny how some consider kerosene a dirty fuel. It is for priming possibly but then the bright yellow flames when using shellite or unleaded are clear to see as well. Alcohol for priming is cleaner but it is easier to prime using the fuel from the stove.

I agree though that the additives to petrol, are designed for carburetors and fuel injection whereby the fuel is injected away from high temperatures. I would be interested to hear from a petroleum chemist on what the additives might be.

I will continue to use unleaded though and see what happens but periodically I'll got back to shellite or kerosene for the DF. It burns just as well as shellite, as far as the eye can see. I was watching it last night and the burn was impressive. The worry would be hard deposits in the jet itself that might be hard to detect but would reduce performance, either temporarily or permanently.

I have had some strange burn issues from time to time but there was quite a bit of rubbish underneath the burner of the DF and at that point it was burning with a green tinge so I think that was swarf disturbed but left during manufacture.

It is great to use the stove outside...just for fun and get used to it. I did some pancakes for breakfast on it.

 

Gasoline (petrol) additives – update

Catalytic converters are put there to protect human health. While stoves don’t burn much fuel, we are typically breathing much closer to them than an exhaust pipe…

 

I know indoor gas heaters using piped natural gas is known to form nitrogen oxides and also fuels such as diesel and perhaps kerosene can form small particles that can go deep in the lungs.

My bet is that any fuel is likely to produce unhealthy products, not simply the by-products of perfect combustion, carbon dioxide and water.

In the Soto Muka manual they clearly state that unleaded fuel can be used.

My feelings are to just see what happens. I understand the use of Shellite and the reasons for it. Petrol is simply a variable and potentially evolving product and its composition will vary certainly from country to country.

I appreciate the reference on additives. I would be interested specifically in what goes into our fuel here in Australia. We are not in the days of tetraethyl lead though, but it seems they might still be using this in Avgas to boost the octane.

I guess if I have trouble with o-rings I will know is the ethers and aniline products in there. I doubt any petroleum product is free of a cocktail of chemicals such as aromatic compounds arising from the source oil, it won't just consist of hydrocarbons even if Shellite or Coleman or MSR fuel is used.

Combustion is toxic and even ethanol has higher order alcohols and other chemical impurities in it.

 

There is a saying I like that applies to more than just wearing Spandex clothing.

"Just because you can, does not mean that you should."

 

Howdy, All,

I am amazed at those who want to do things, even though those of us who have many decades of experience, warn them against doing what they want to do. Having suffered through trying to deal with the damage that most auto gas creates in camp stoves, for friends who unwisely chose to use that fuel, I will NEVER use auto gas unless there is simply NO other alternative! Period! But, we keep getting new members, and even some of our older ones, who wish to "see for themselves". Brings to mind something that happened in the Boy Scouts, seemingly a lifetime ago. One of our guys was trying to chop some wood, using a crappy scout axe, and his knee as the chopping block! The Scout Leader came over, and patiently explained why he should not do that, as it was dangerous! No sooner had the Leader turned his back, than the ignorant scout took on last swing, and missed the wood altogether, sinking the axe into his knee! Blood? Oh, yeah, there was a lot of blood, and the wound was deep! The scout was rushed to the nearest local hospital, for treatment, including lots of stitches, and a ruined camping trip!

Because auto gas can, and does cause unnecessary clogging, I seldom offer to rebuild anyone's stove these days. Too much hassle, and too much of a pain in the arse!!

Stick to the fuels that the stoves were designed to burn efficiently, and cleanly. Leave the auto gas for the autos, unless it's emergency! Just my 'tuppence, and I'm sure others will disagree with me. Darwin was right!! Sigh....

- Doc

 

Seriously, what @Doc just said. Learn from others’ experience!

Yes, white gas is more $pendy than automotive gasoline. But I don’t burn a lot of it. Cost for stove fuel, even expensive stove fuel, is a minor expense compared to the cost of simply travelling to my destination. And it is worth it to have a more reliable stove. Unless I get in a pinch and white gas is simply unavailable, I am not going to be burning automotive fuel in my stoves.