Petromax hanging lamp type 795

I returned home today from Luxor, Egypt, with a Petromax 795 Hanging lamp which I picked up at a small stall in the Souq at a very reasonable price. I tried to find something about the lamp on the Internet, with no success, except for a list of items mentioning the 794 (with pump) and 795 (without pump). Sure enough I checked the lamp (dismantled in my suitcase) and it has no pump. I can't imagine how it works, unless the preheater warms up the copper tank enough to produce enough heat to create pressure to keep the flame going. The preheater seems to be missing, there is no dish for alcohol that I can see, although there seems to be provision of a hinged something which might have been a dish. Does anybody know how this lamp works or have any diagrams showing the preheater system in enough detail to allow me to copy the missing parts. I will post some photos in a couple of days so that you can see what it looks like and what condition it's in.
It's not bad, though the light grey enamel is chipped in several places. The inner rings of cast iron are rusty but will clean up.The various tubes seem to be in good condition but corroded. The copper tank is pretty dented and it does not seem to be the type that I can unsolder to beat out the dents, but, polished up, it will look fairly respectable.
The lower body has "Petromax" embossed on one side and something in Arabic in the enamelled on the other side, though this is on the worse chipped and will (I think) be undecipherable.


Jim.

 

Does it not have a valve in the filler cap to allow pressurisation via a bicycle pump?

 

It does have a valve like an SRV, but I do not see any way of attaching a bike pump to it.


Jim.

 

The filler cap has "wings" and the same thread as the Petromax 600CP lamp.

Jim.

 

795 is basically a model 835 but with a copper tank instead of steel and a cycle pump/filler cap instead of an integral pump. The internal workings are pretty much the same for a range of these lamps so if you look in the galleries for Petromax hanging lamps you will see what your lamp burner and other parts should look like. ::Neil::

 

Read Petromax 500CP rather that 600CP!

 

Thank you, Neil, that is very useful information. Do you know if spares are available for these lamps? I need a reflector/globe holder, globe and an adapter for the filler cap to a bike pump fitting The Petromax adapter does not fit (slightly smaller thread).

Jim.

 

I guess, 450Hk is better.

 

450 HK is better than what? I do not understsnd!
I have had a look at the filler cap, it has a 4mm threaded tube with a threaded protecteive cover on it. I guess this is what is used to pump up the pressure, but it does not fit any of my old bike pumps!


Jim.

 

I ntill cannot any recipient for the preheat alcohol. Is this in one of the two lower castings?
I still can't find any picture of the insides of this lamp!

Jim.

 

The lamp is now reassembled. Many of the brass screws were bent, twisted or missing, so I searched our supermarket for replacements. All they had were Cross-headed ones, so I had to use those. It looks reasonable, still polishing the copper reservoir, the dents do not look too bad, the two halves of it are brazed together, so I can't do any panel-beating on them. Still trying to understand where I pour the alcohol for the preheating, I would be grateful if somebody could explain how it works!


Jim.

 

Jim, beter in the context of what is correct. original these where 450Hk not 500cp or 600cp.

Having wrote this: do you have the original steel jet with copper mesh inside ?

I once made a restoration text on petromax.nl for a 834 which as for workings is the same.

The cast irion base plate should have an opening with cover plate to pour in the pre heating alcohol.
You did check that you have a good non leaking pre heater disc ?

 

Wim, you are an angel, thank you so much for this data!
I was only referring to the 500CP lamp because I had found that the 500Cp nozzle will fit this lamp, It is nice to know that it is a 450 CP lamp. You have answered my question about preheating. i do not have a white enamelled dish, just the two cast iron "dishes". can I make a dish to fit in it? Maybe out of brass or aluminium?
The spiral tube on the preheater is not there, it is just a half circle which runs around the lower cast-iron dish, it looks original. I suppose the heating tube fits into this White enamelled dish?
I have now so much information, I can continue with the restoration. Thank you for your help, it was exactly what I wanted. My faith in the forum is restored!

Jim.

 

I have the jet that was in it, but I do not know if it is Steel or brass. it is not blocked.Is the steel jet important?


Jim

 

I do not have the preheat dish or its igniter. If anybody has one for sale, I would be very interested!

Jim.

 

Jim,

I am pretty sure I can't follow you here. You have two cast iron discs ?

And which spiral do you refer to ? Normally there is only one: that is the generator/vaporizer (like the preston loop) On my website it is the generator group.

You can make a pre heater disc from an ashtray. It should fit on the three prongs on the bottom side of the cast iron disc. The igniter is a bonus but not necessary.

http://petromax.nl/Px834.html

 

Yes, I have two cast iron discs which are screwed together but no container below the Generator which is coiled around the burner. The second part of this coiled tube is broken and I need to silver solder a new brass tube to replace the section that somebody has removed as a bad repair. I will try to find an ashtry or something of the correct dimensions to replace the preheater dish.



Jim.

 

I have repaired the heater coil this morning. I had great difficulty bending the replacement brass tube until I found a report from somebody who filled it with (sandblasting) sand, then heated it to a dull red and bent it by hand! it worked beautifully! I soldered the jet end into the jet holder which I had drilled out to the 8mm of the tubing and fixed it in place with the two screws. I was then able to solder the other end of the tube into the piece of larger tube attached to the filter and adjust it to allow me to screw the filter to the correct position. I hope the lead-tin solder will resist the temperature of the pre- heater tube!
Now to find the right material to make the pre-heater dish, unless anybody has an original one to sell me!


Jim

 

You seem to have been lucky with bending the brass tube. Brass is funny stuff and can become hot short which means it will break if you try to bend it hot. It can also be cold short when work hardened and break when bent cold. Depends on the composition of the alloy. Normally the best aproach is to heat and quench to anneal and then bend it cold. ::Neil::

 

Jim,
lead tin soldering in the area of the vaporizer, pre-heater and the like might not be a good idea. Temperature in this area will easily raise to 300 deg Centigrade and above, which will melt the solder joints.

There is somebody in German ebay who sells preheater dishes for Petromax hanging lamps. Just type in (or copy/paste) the word "vorwärmschale"

The ignitor would not be a part that is indispensable. When the vaporizer is hot enough the paraffin fumes exiting the jet will get sucked up the chimney and be ignited by the preheating flame. However, the solution with the ignitor is smarter...

Good luck, Martin

 

Thanks, Martin, I'm not sure about the lead/tin solder, i can't do it with silver solder. It's worth trying. Thanks for the tip about the vorwärmeschale, I'll look for it.


Jim.

 

Jim,
it's not "vorwärmeschale", but "vorwärmschale". Otherwise you won't find anything...
BR, Martin

 

Thanks, Martin, I make mistakes in German!

Jim

 

I found his pre-heatig dish, I can't see the slots to attach it to the 3 posts, maybe he photograhed it before preparing it for enamelling. I'll have to phone him. His reflector looks great, but 166 Euros? I suppose that where there is no other source, it's a good price!
I have trouble with the filter, I can't get the mesh filter our! There does not seem to be a screw in the hole and I have tried drilling it out, without success. Anybody know a good way to do it?


Jim.

 

Jim,

You always can try making one yourself. Btw, I guess that what you see is what you get. So no enamel and no three prongs.

 

Hello, paul, Firstly, let me apologise for not answering you before, I did not notice my notices!
I need a reflector, the Preheat dish, preferably a good preheater filter and coil and a pressure meter (mine is very rough!)I will try to e-mail the photos that I have.


Jim

 

I've found an original alcohol dish and it's on its way and i have managed to clear all the Tubes of the fuel supply and the preheat coil. the filter mesh had disintegrated and blocked the tube for most of its length, I had to drill most of it out! The jet seems to be partly blocked, does anybody know what the diameter of the correct hole is? I tried to clear it with very fine copper wire but it did not go through


Jim.

 

I don't know the exact diameter of the orifice in the jet but if the jet in your lamp is the correct one, a 350 cp (or less) cleaning needle should clear the hole. Alternatively, the pricker used for cleaning the rapid pre-heater nozzle.

Have you tried heat and quench ? Thermal shock quite often works wonders.

 

Hello, Henry, I did know that there existed a rapid pricker! I have not tried heat and quench yet, but I will do it tomorrow, if not there are new jets available on the net. it's coming along, I hope that I will soon have photos of it working!


Jim

 

Jim, very good possible that there is a mesh inside the jet. Check that first please.