I can see the Swedish patent but cannot access the English equivalent. My Swedish is nil. I would much appreciate an explanation of how the patented filler improved over the prior art. Kind regards, Jaime Massang.
Hi Jaime and welcome, You may be referring to how the area of the tank around the filler tube is recessed? This was patented. I'm not familiar w/"the patent" and there is more info and there are more examples but for starters IF that is what you are asking about... if so credit @Ray123 if you scroll down in post (link below) you will see some mention Ray made of this on a 1931 Primus No.1 (and again there is more). https://classiccampstoves.com/threa...ated-alcohol-silent-burner.26590/#post-270376 thx omc
Hi @ Jaime. With Pressurised kerosene stoves it is important that they are not over-filled with fuel. Ideally there should be up to 25% free volume above the liquid level. It is this air volume which is pressurised by pumping and fuel is displaced upwards through the fuel feed tube, and riser to the burner. Sunken risers ensure that the tank cannot be over-filled, as when the liquid reaches the rim of the filler, and you cannot add any more, there is still the necessary space at the top of the tank. The same effect can be achieved by having a tube protrude from the filler nozzle a short distance into the tank. Again there will still be free volume above the liquid when you can't add any more. Some manufacturers adopted this approach. Trust this helps, Best Regads, Kerophile.
Hi, it occurs to me that I should perhaps have gone back to first priciples: 1. Liquids and solids are essentially incompressible. You can apply very high pressures but their volume remains essentially unchanged. 2. Gases and vapours are compressible, and their volume can be much reduced by applying pressure. 3. Because of these properties pressuried liquids and solids do not store much energy. If you fully filled a pressure stove tank with fuel you could pressurise the tank very easily, with perhaps a single stoke of the pump. This would allow you to light the stove but as soon as a small volume of fuel was consumed, the pressure in the tank would fall and no further fuel would flow to the burner unless you pumped little and often. This is because there was very little stored energy in the liquid in the system. 4. If, on the other hand you have an air volume of up to 25% of tank volume above the fuel, you can pressurise the system to a high pressure by adding to this gas volume. The more you pump the higher the pressure of the gas and hence the fuel. When the stove is lit fuel is consumed but there is lot of stored energy in the system in the form of pressurised air. Fuel will continue to be fed to the burner. 5. As the tank is heated by conduction and radiation from the flame, the tank will become self-pressurising to a great extent, and you may not need to pump much more as the fuel is consumed. As an aside, the incompressibility of liquids is useful in other ways: Pressure vessels are proof tested by being filled with a liquid (usually water), which is then progressively pressurised. The pressure in the system is monitored and as it rises, the pressure vessel is stressed, but should it leak or fail, there is very little stored energy in the system and bits of the vessel will not fly about and kill/injure people. You never pressure-test using gasses because there is so much stored energy in the system, that should it fail, a lot of flying debis could be generated. Best Regards, Kerophile.
Kerophile has given the perfect explanation of why the recessed filler was introduced. The diagram below is from the Primus patent which was applied for in 1919. It can be seen that if the tank is filled to the bottom of the filler tube there will still be a sufficient air space to pressurise and so make the stove functional.
Thank you all for responding. Obviously, I did not realise that a volume of pressurised air was needed for sustained operation. This being the case, I wonder whether there is an optimal volume of kerosene to air in the tank to continue without pumping? I am designing carry boxes to house my stoves and will attempt to post pictures in the near future: a Hipolito No.0 (roarer), Primus No.1, (silent conversion;"R32" stamped on bottom) and Burmos 55 (silent). Kind Regards, Jaime Massang.
Hi Jaime, have a look at this thread: https://classiccampstoves.com/threads/wooden-storage-transport-boxes.13677/#post-133796 And this wooden box: https://classiccampstoves.com/threads/wood-stove-box.17242/#post-175396 Best Regards, Kerophile
Hi Jaime, to answer your question about how much fuel to add to a pressure stove tank. If your stove has a "sunken" filler you will be limited to the manufacturer's maximum fill amount, however with any other pressure stove: "Fill three parts full" is a useful guide. Meaning Three parts in Four is 3/4 or 75% full. Obviously the stove will pressurise and run with lesser amounts of fuel, but this is a guideline for filling. Best Regards, Kerophile.
