Hipolito 250 repair

Petromax Tonbrenner, 9,95 €
Petromax Tonbrenner HK250 | eBay (same people)

 

A clay burner is made of heat-resistant clay(original style) similar to this:


An oxide burner is made of almost pure aluminium oxide and is even more heat-resistant and harder. It is usually very white in colour:

 

Just a warning: I bought 250cp clay burners some time ago and guess what the amount of threads was different. So make 100% sure you get the right ones.
There fore nos parts are way better.
Besides that, I need other locks on the doors: 10euro a piece ???

Exhaust kit is the stuff you need to repair car exhausts. But I guess they call it putty in stead of kit.
The idea is that you clamp something between the threads when screwing the burner in place.

 

Unfortunately, they do not ship to Greece. The ebay page says "No shipment to Greece". I wrote them an email in case they could do it but no answer. If they do not answer by Monday I will write to base-camp.

 

Since we discuss burners, I have seen brass burners too (#3). They are expensive but what about them? They come with the part than they screw to (#34). I try to examine my options. 10 euros for clay, 18 for oxide, 25 for brass, all these plus shipment and customs. None of those exist in EU (which is kind of strange when Petromax is in Germany).

I will also look the exhaust kit to understand how it could be used.

 

Do you think exhaust putty can fix this somehow? The two pieces do match together.

 

I do not think so. Even if it stuck together it would drop off at some point costing another mantle.

 

May be worth trying a repair? use the exhaust putty to glue it back together then maybe use some stainless or nickel wire tied to hold it in place?

the wire would have to be thin enough to be flexible but thick enough not to oxidise?

i thought I had read of some members affecting such a repair :/

 

Interesting repair with the wires. I will try it out of curiosity. At least Base Camp ships to Greece.

 

I think Base camp will ship anywhere that is legal !

 

It took quite some time to get the needed parts for the 250 and test everything. So I cleaned the vaporizer and the Preston loop with a Bowden cable. Also repaired the pump valve, replaced the burner and the nozzle with new ones. So I tested it yesterday using a Pmax pump adapter and a Pmax fuel cap with pressure gauge so I know at what level is the pressure. The mantle looks a bit on the yellow side but my tablet can not really show the color although I tried. Maybe I had to adjust a bit the screw on the J tube but I forgot about this point. Here are some pictures:

 

That looks very bright.

There's nothing to stop you adjusting the screw but it could just be the mantle. Older mantles used thorium which gives a bright white light but many modern mantles use non-radioactive yttrium which gives a softer slightly yellow light. As long as there are no flames outside the mantle the lantern will be fine.

 

The mantle looks pretty bright in the pictures. Don't know how it appears in actual.
You can adjust the J-tube 'flap' screw until the mantle glows with the brightness or whiteness you desire.
What mantle are you using for this?
Usually, but not always, the older radioactive thorium types tend to be 'whiter' in terms of light colour appearance.
They might or might not necessarily have a greater luminance than the newer types.

 

With other mantles you can only cover up the problem but never solve it.
I know the problem and recently explained it in detail at the presentation of my Geniol automatic brass 250 cp.

 

Looks great ! - although do I see the top cap/ventilator not where is should be ? - this can disrupt airflow. nice looking lantern

 

The mantle I use is a modern Petromax mantle for 250. I actually like the golden glow of my lamps, I am not into the whitest possible. So this is OK for me from the color side if the fuel burning is correct. I do not see flames around the mantle. So I assume the lantern works properly. But I do have an observation I would like to ask about:

The fuel cap with the pressure gauge and the pump adapter get much hotter than on a Petromax 500. Not to the point of not touching them, but noticeably hotter. I thought that this could be due to the fact that they are closer to the mantle, as the 250 has smaller dimensions than the 500. Is it so? Same goes for the fuel tank. It is a bit hotter to the touch.

The burner (forgot to say) is not a clay one, but an aluminum oxide. I do not know if these burners burn hotter or not compared to the clay ones.

The vaporizer, I had written before, is not straight but somewhat bent. I did not attempt to fix this, as the rod and the needle work properly with the nozzle.

 

Oh, yes, I put the ventilator after the lantern was lit and it was to hot to place it properly. I will fix this.

 

About nozzles: this thing always works with the needles. How is it designed internally? I find it hard to believe that the needle just always finds the orifice without any help. There must be a geometry inside the nozzle that guides the needle. Something like a curved inverted v, like this maybe?

 

Often the Petromax 200/250cp body gets sensibly hotter than the 500cp. Sometimes due to its jet being a little worn and burning more fuel than designed.
Often times, just due its size being smaller and has a relatively smaller capacity to conduct heat over a larger mass like the 500cp versions.
Alumina(aluminium oxide) burners don't burn any hotter than clay ones. They are only a little bit more refractory and heat resistant.
The internal section of the Petromax jet just before the orifice is conical(hollow). In some ways, it assist in guiding the needle towards the orifice/hole.
Besides that, the constricted section of the Preston loop vaporizer also serves to keep the cleaning rod more or less, centred.

 

Ah, OK this explains why I feel it hotter. It must be the small body as the jet is new. The conical construction below the hole justifies that the needle find its way. Because I have seen several needles that are not absolutely straight with their base where they are attached. However, they always find the hole.

 

@MYN

The alumina nozzle is superior to even NOS ceramic nozzles as it's more resistant to heat while being more shock resistant.

The next step up is an all brass nozzle which I assume is made at great expense to fabricate and machine.

 

Material wise, the refractory clay nozzle is predominantly made up of crystaline aluminium silicate materials, which have a somewhat lower fusing temperature than pure aluminium oxide.
***The temperature ratings for general refractory materials like bricks, castables and mortars intended for furnaces and kilns are usually proportional to the aluminium oxide content.
Ceramic burner nozzles made of pure, sintered or fused aluminium oxide would certainly have higher ratings than 'regular' clays or even fireclays.
Aluminium oxide is among the most economical refractory materials in common use besides regular clays/fireclays.
Any higher ratings than possible with aluminium oxide would require more expensive and higher temp rating materials such as zirconium oxide. To ensure dimensional stability and prevent thermally induced fractures, the zirconia would usually be doped with some yttrium, calcium or magnesium oxides. Among the most expensive ones being yttria-stabilized zirconia. There had been some thorium oxide crucibles being made for very specialized purposes but these are not common...or should I say, pretty rare.

Pure carbon/graphite and silicon carbide also have higher fusing temperatures than aluminium oxide and many other materials. However, they would still 'burn' or oxidize in the presence of oxygen and therefore not suitable for burner nozzle construction.

Brass nozzles would certainly be more expensive than clay or even aluminium oxide ones. But then, they are far less heat or oxidation resistant.
They are mechanically stronger though.
Any metal that is continuously glowing at or above red-heat in the presence of atmospheric oxygen isn't going to last as long as the ceramic oxide materials.
That includes the highest melting point metal, tungsten...simply because oxygen would be present in such applications.

 

Lots of interesting information. Thank you @MYN Does your comment about metallic burners include the stainless steel versions sold by Petromax?

If I understand you correctly it seems that aluminum oxide is the best choice for durability. True?

 

Congratulations Antonis

 

@Antonis Tsolomitis
Yes, that includes stainless steel.

 

@MYN @Antonis Tsolomitis

Stainless steel is an awful material for nozzles, the thermal expansion coefficient is the worst compared to all other aforementioned materials meaning it'll expand and stretch anything it's in contact with, or loosen from. In the case of burners, you'll ruin the soft brass mixing chamber as it stretches out the threads making them loose. Stretching the nozzle also will break your mantles from expansion as the mantle is extremely fragile and brittle. Also under direct exposure to combustion, the stainless steel where exposed eventually loses its corrosion resistance as the various exotic metals like chromium starts to oxidize and diffuse out from the steel. Steel itself starts to oxidize once those exotics are consumed and will start to flake from the expansion from use.

Users of these stainless steel nozzles reported these nozzles eventually start blowing slag, wrecking mantles as the screen starts disintegrating, throwing flakes of steel.

 

Indeed @Dashwood
I've never had those installed on my lanterns.
Not just expensive, but not getting much or any positive reviews as well.

 

The situation for ceramic versus stainless steel is clear with all the above. But it remains unclear the choice of brass burners. Judging from Coleman they should be OK. Coleman uses a brass burner I think. Say in the current 639C model. Brass burners are sold together with their housing, I guess to compensate for expansion. @MYN says that it is metal and in the presence of oxygen it will oxidize. And is this important? Even if it oxidizes what could the problem be? Will it chip? Again, Coleman is my typical example for this.

 

This:-

Also, in general, the burner region of an operating Petromax gets considerably hotter than those found on most Coleman lanterns. In particular, 350 and 500cp units.
Sometimes, even the loop of the vaporizer would glow red.

 

I see. So Petromax 350/500 get hotter than Coleman, and this causes the trouble. OK.