Fixing "Halo" around mantle for Petromax

Nice to see this post!! Gives me some hope on .. I recently bought a 'made in India' Petromax clone (brand Cemax) and I am facing the same problem of a flame halo around the mantle, a dim light and a blackening mantle. I am new to kerosene/Petromax and almost gave up on my adventure starting the Cemax.

(I own three Colemans (2x 285, 1x 226) for a few years and they work fantastically to this date )

I've tried changing the mantles 150/350/500 CP (the jet says its made for 350 CP), adjusting the needle height and changing the pump's leather cup, but still the same problem exists.

The only thing I haven't tried is adjusting the height of the U tube from the jet. I'll try this and let you know if I suceed..

 

Welcome aboard!

 

Indian Camper, those things you've tried will hardly help in your case.

You say that the only thing you haven't tried is the adjustment of the U-tube, but I haven't actually seen anything about exchanging the jet!
The jet is one of the most crucial thing to a lantern, and also one of the parts that wears out from normal use, so my guess is just simply that you need to change that one.
A worn jet give you exactly the symptoms you describe due to a too rich fuel to air mixture.

An easy way to (hopefully) confirm this is to partially rise your cleaning needle once the lantern is heated, well pumped up and running.
Slowly fiddle about a bit with this, and at some point you will get where the jet is blocked just enough to give you a better proportion between air and fuel. It will not run as well as with a new jet, but hopefully you will see an improvement in the light at a point where the jet is partially restricted to simulate a new one.

*Edit: Oops. Come to think about it... perhaps you bought an entirely new lantern since we're talking about an Indian Px-clone?
In that case forget what I wrote. It would be very strange with a worn out jet on a brand new item.

 

Hello Indian camper,

Besides all already mentioned: you could check the fuel pick up too. Old and new lanterns can have debris of some kind in them.

The adjustable dimensions can be found here: Px table

Also look at the air tube paddle it is designed to to just that : adjusting the air-fuel mixture so that it flow better into the mantle.

The size/volume of the flame front should create the shape of the mantle. If for some reason the mantle doesn't like this shape the two don't match and you will get a hallo.

But it all starts with a good jet, needle and adjustments.

 

Chirster and WimVe, thanks guys for your replies.

Here are some more things I tried:

Adjusted the J tube height to max. No solution, same halo and dim light.

New jet - yes the lantern is new, but anyways I bought some new jets (nipples), 350 CP, and screwed them with a bit of teflon sealing tape, making sure tape bits do not get into the generator tube. Again, the new jet wasn't a solution..

Leak check - I also pumped up the lantern without kero and immersed it in a bucket of water to check for leaks. Passed, no leaks at all whatsoever. (I took care that no water entered the tank through the pump assembly)

Just out of curiosity, I took a sewing needle and enlarged the hole of the jet. After this the mantle burned brighter, although may be at around 25% of the full brightness of a Px. The blackening and halo reduced somewhat.

Fuel and mantle check - just to make sure these weren't the problem I transferred the kerosene in the Px to my fully empty Coleman 285 two-mantle lantern onto which I put two new Px mantles. And lo and behold after an initial 1 min of hiccups (I did not even preheat !), the Coleman shined in it's full glory burning kerosene, even though this lantern is not equipped with a kerosene generator and is strictly made for white gasoline. So fuel and mantle check out. Indirectly, this also means that my Px isn't lighting up because of a generator or heating problem, because the Coleman proved that a simple vertical tube is enough to vaporize the kerosene. (With the Px, I preheated the generator for 3 min with spirit in the cup.)

So my next hope ..and also my hunch.. is that something is blocking the free passage of fuel/pressure from the tank into the generator. Will try a complete overhaul and check of all systems next and report out what happens.

 

Well, I know little about P'max and P'max style lanterns but I think I'd be changing the generator if I were you. Possibly it's becoming choked with carbon or worn where the pricker rod passes through at either end of the Preston ring. But as I say, I'm stabbing in the dark...

The other thing, I thought the air paddle was to produce turbulence in the fuel/air stream to promote a better mixing of the two before combustion. I'll stand to be corrected on that one, too...

 

Hhmm, what type and brand of lantern do we, de facto, talk about ?

For the record, you use kerosene (petroleum), and you have a 500cp jet/needle with 500cp mantle or 350cp jet and needle and a 350cp mantle.

Putting the air tube at max. isn't a solution. You should measure the distance between jet and tube.

 

Wim, it's a Cemax from India, as Indian Camper stated in his first post.
The jet is stamped 350CP, so considering it's a brand new lantern, well... my guess is that it's a 350cp lantern.
Saying that, I would probably tie a 400/500 mantle to it myself. They always work.

 

So I totally dismantled the lantern, checked every part and put it all back with a new jet, checked pumping mechanism with water. The lantern and parts appears to be of quality make and build, and the pumping appears to be perfectly alright.

Then, after a leak check with in a bucket of water, and drying out the insides completely, I filled up the kerosene, preheated with spirit and lighted. But the same problem as before occurs and this time I ended with a totally black mantle and an orange flame after an initially half bright mantle for about 2 minutes Pressure in tank seems OK. Not sure what else I can try.

Like Christer mentioned, the lantern has a 350 CP jet and a 400/500CP mantle.

The only thing I could not overhaul is the font (the "pipe") from the tank to the outside (..to the needling mechanism and generator/jet). This joint did not appear to be a threaded one, and looked like some special seal was holding it in place - a rubber gasket and a metal ring - tightly squeezed. I read somewhere that there is a 'vaporizer valve' at the font inlet inside the tank and that a malfunction of this valve can cause a blackened mantle. Does anyone here knows better on this matter? Why is there such a valve and what is its function? Is it there in all types of Pxs / is it a must? How do I replace it, since it is inside the tank?

Here are some pics.

 

Other than the pumpknob, your lantern looks identical to my Indian Phillips. I've used it this weekend for 2 nights at a Living Hystory event, and it performed perfectly. Mine however is a 500cp model. I did have a problem last week giving it a try-out after fitting a new mantle. Halo and blackened mantle et all. So I switched it off, fitted a filling plug with build-in manometer (cheap copy of Pmax ), gave it a double prime and off she went! Took a while to burn off the carbon but all went well. I did pump the fount to 1.5bar, the max is 2bar.

Best regards, and welcome to the forum!

Wim (the other one )

 

One thing leapt off the screen at me here. Sealing the jet with Teflon tape may well cause a poor burn and sooted mantles. Teflon is prety good under heat but it won't stand the temperatures you get at the jet. It will burn away and you will possibly get fuel leaking out around the base of the jet which massively increases the fuel supply. Clean off the jet threads and if you have to use a sealer smear a little copper slip on the threads. ::Neil::

 

Yay !! Finally I got the lantern to work Here is a pic. No black mantle.. just bright light

I found the problem to be with the burner system - U tube - that was causing the blackened mantle. I bought another lantern of a different make which had had a more "advanced" burner with a more narrow "U" bend and a turbulator paddle inside.



Next task, to fix the Cemax U tube and to find out why it causes black mantle.

 

Pic

 

Excellent!

 

Some lessons that I learned from getting a blackned mantle with halo to a super bright lantern:

1) The jet (nipple) has to really tightly fit into the generator tube and be absolutely leak proof at the threads.

2) Pressurize the fount to about 2 bar and no less.

3) Gap between jet hole and mixer tube should be ~13 cm for a 350 CP jet. Also ensure that the jet hole is well aligned with the mixer tube. (I sawed off 2 mm from my mixer tube to get this gap to perfection)

4) The burner assembly - clay nozzle and threaded brass holder - have to be snugly fit without any gaps/looseness between these parts and also to the mixer tube.

5) Colored kerosene is just as good as white kerosene. Somewhere else I read that colored kerosene can cause blackened mantles. This is not true as far as my experience goes. In India we get 'blue' kerosene as well as colorless one. I tried both, and both work very well.

6) I used Isopropyl Alcohol for preheating and it works just fine. (Methanol cannot be bought in India in retail outlets, because people drink it and become blind)

7) Most important - patience

 

Yes, patience is required!