Høvik Verk Standard No. 37 - strange flame behaviour

@Radler
Because of having to add pressure every 5 minutes or less. That is far from normal, at least for 1-pinters, and I assume it is for larger stoves as well?

A leak between the burner and riser tube that causes such a rapid loss in air pressure would give a rather large liquid or vapor leak, right? (Because all the loss of pressure would have to be caused by decrease in volume of fuel.) I don't think this is the case. Could the vent screw or tank lid start leaking after heating up?

 

At the beginning there is liquid fuel at the riser tube connection, sure. With rising temperature, the level of liquid fuel may well be below the Burner/riser tube connection.

Btw. How much fuel is in the tank? If the level is very low or too high, you will have a problem.

Radler

 

Air leaking into the riser could explain that behaviour - got a LPG canister with some bad content, had to shake it every minute to keep a small stove burning but it had that pulsating flame, worked well with a big stove.

 

@Radler
Not sure I understand what you mean. Could you maybe elaborate? Why would an increasing temperature make the liquid fuel level go down? Consumption of fuel over time by the burner would cause that, of course, but temperature in itself? The vapor-liquid equilibrium will shift towards a higher vapor-pressure with increasing temperature, but I belive the liquid fuel level/volume will hardly be affected by this. A rough estimate can be made using the ideal gas law and some fair assumtions about the partial pressure of kerosene vapor in the tank.

How far down into the tank does the riser tube usually go? I always thought they went pretty far down towards the bottom. I have had the tank filled between 1/2 and 3/4 for all my test runs. I have probably spent more on fuel for testing than I have on the darn stove itself

 

@HaakonJ
Now, after I have seen the video, (which didn't start before), I am almost sure, that the jet of your stove is much too wide. There is too much gas and too little pressure, the mixture is too rich (yellow and sooty flames).

The gas-phase in the burner has always the same pressure as the air in the tank. Under normal conditions the equilibrium is achieved by the amount of fuel which is vaporised. When more fuel is vaporized as is escaping through the jet, the pressure in the burner gets higher and the liquid phase in the riser/burner is forced downward to the cooler parts. The result is less vaporisation and less pressure. This is the principle.

If the jet is beyond a maximum size (worn out), the equilibrium is not stable. More vapour is leaving the jet, than can be vaporised, the level of the liquid phase rises slowly. This will cool down the burner a bit and this means the vaporising rate becomes even less!

If you force the pressure now by pumping more air in the tank, the liquid fuel rises a bit to the higher and hotter parts of the burner/riser. For a moment you have some more vapour, but the vapour pressure will sink again. The jet just lets out more vapour than can be produced.

Also if the jet is too wide, the gas-speed is too slow to move enough air into the mixing tube (the tube above the jet). The air/vapour mixture, which is expanding (heath!) between the burner caps must have a minimum speed to make the burner work properly.

The leak is in the jet! :-))

Best Regards
Radler

 

@Radler
Ah, now I understand what you meant, and it makes sense. I thought you were talking about the liquid fuel level in the tank, not the riser tube, which got me confused. However, the jet used in the video is brand new, so it is not worn out. And it is the same size as the one that came with the burner (behaves the same with both jets, at least). If the jet is too large, this means the jet that came with the burner is enlarged, or a too large jet was installed by a previous owner. I will try a jet with a smaller hole (one that works with a 1-pint stove).

 

The gallery on this site has images of this stove with the roarer burner, the silent burner and a regulating burner.

So why not get some guilt and Cheat. Buy a new burner solve the problem.

 

Well, I did end up cheating a lot. I picked up another copy of this stove just after buying the first one, cheap as chips, as it was not complete. Missing the outer burner cap and a nipple. Arrived today. I just did my usual new-stove-routine of cleaning the tank, oiling/replacing the pump leather and replacing all rubber washers/nrv-pip.

After cleaning, I incidentally had a small amount of fuel on the tank. Wanting to see if the burner could let air through, I gave the pump a few strokes. To my surprise, fuel came out of the nipple. «Why surprised?» you say. «You had fuel on the tank, dummy!» Yes I did, and the reason for the surprise was that on the other stove, I had to put far more fuel in for the same thing to happen. Either the riser tube goes further down into the tank on this one, or the first one I bought has a hole in the riser tube. I now believe the latter must be the explanation for the strange behaviour seen in the flame. I took the necessary parts from my first stove and made a working copy of the second stove:


Has anyone ever fixed/replaced a riser tube in these types of stoves? Lot of soldering work? Not sure what to do, but I might just end up scrapping the first stove and use it for spares.

Håkon

 

I miss a systematic search!
Is the riser tube clear from any dirt? Can you see the bottom? Can you blow air easily through it?

If there would be a leak in the riser tube, check it: Remove the burner, fill water in the tank 3/4 full, turn the tank upside down and look for water with or without pressure.
Most riser tubes are not repairable because they are fixed with a nut and solder in the tank. Only to fix a inlaid tube could help in this case.
Some old models were soldered only and could (in theory) be repaired.

Radler

 

@HaakonJ I am not sure I under stand what you see as a Riser tube as it fits into your stove. The riser tubes on my Aida 100's and my butterfly 2412 stoves are removable. When the Riser tube is installed it screws into the top of the stove into a bung fitting that is soldered to the brass stove and extend into the tank. From what I see in the Gallery your riser tube is not removable and I assume it extends into the stove. I am just wondering if your stove uses a wick inside the tube that extends into the tank and that it may be plugged up causing the bad flames you are experiencing? I see by the gallery images you have what I see as a very long riser tube that looks like it requires a wick. I am wondering what a diagram of the stove looks like. I am not able to get into the reference library on this site.

 

The riser tube is free from dirty, I can easily blow through it. Difficult to see the bottom, but I dont see any obvioius obstructions (like a wick or dirt). If I fill the tank 1/3-1/2 with fuel and pressurise the tank, air is coming out of the jet. I dont see why it is necessary to do the opposite (like your suggestion with water), as the logical conclusion would have to be the same? Isn't it basically the same test?

 

@Radler I tested with a 3/4 full tank of water (upside down), and the result was as expected: water came out the nipple hole. Not by itself, but from the first pump stroke. When I get my burner washers from The Fettlebox, I will try the misbehaving burner on the new tank. I suspect it will work just fine.

@HercL4D2 yes, there is a thinner rising tube extending from the top of the tank and some length down into the tank. on my new burner it goes almost to the bottom of the tank, as it ran on less than 1dL of fuel. Between the top of the tank and the burner nut, the tube is wider. I am not sure I understand why a (very) long riser tube requires a wick. Could you explain?

 

Some stoves like the Svea 123 variant stoves use a wick. The parts catalogue for your stove does not call out the use of a wick, so forget what I posted. There is a post here that talks about orange flames with mismatched silent inner and outer caps. Rebuilding a Marine Stove Kerosene Regulating Burner: an Illustrated Tutorial

 

Just an update after receiving the washers: this is the burner of the old (misbehaving stove) mounted on the new tank I got. Has been burning like this for 30 minutes. No pulses of yellow flame, and no burping from the tank.



After all this testing and head scratching, I can not think of any other explanation than a hole in the riser tube, inside the tank of the first stove I got. Please enlighten me if anyone has a different idea, as I really want to understand this the right way! This stove fettle (and thread) has been a good learning experience. I have gained some new insights about the transition from liquid to vaporized fuel, and how tank pressure actually affects the vaporization. A big thanks to all who have contributed!

Cheers,
Håkon

 

Nice working stove. !!!!!

 

Hi @HaakonJ Beautiful flame pattern.

If your “old tank” is sacrificed we will know if the dip tube was/is faulty:

Valor No.51 Dissection.

Best Regards,
Kerophile.

 

@kerophile
Thanks for the idea! I actually thought about doing that, unless there is a way I could repair it?

 

If competent with soldering or brazing you could put a brass tube "liner" inside the existing dip tube (which you suspect is leaking). You need to do this from the top of the tank as there is no other access point.

Best Regards
Kerophile

 

USB endoscopes are very inexpensive on Amazon and EBay, and would let you take a peek inside your tank without disassembling anything.

 

I had a riser tube come unsoldered in a 00. I replaced it with a longer tube that reached the bottom of the tank so it would not slip down as I soldered it. I drilled an access hole in the bottom to let the fuel in. (See sketch) it was a very easy solder job. Cleaned the parts, fluxed it good and soldered the joint. It worked well.
Ivan