Just got an old Petromax HK500 on eBay

I think the light output from the 500CP is a bit to much in the dark. Will the frosted glass option reduce the light somewhat? Is there opal glass options too?

 

Hi, @Malmen
Have you gotten your Petromax to work correctly after the earlier issues?

Sure. Schott Germany supplies a frosted version of the glass globe that fits the 500HK too.
Not sure what which type of opal glass you're referring to. If you mean the translucent variety, then you need to ensure it is resistant to heat and tolerant to thermal shocks, like the usual borosilicate glass globes.
All will certainly reduce the glare from a fully operating Petromax.

 

I messed up the mantle when trying to adjust the air gap. It was only 12 mm and I set it to 14,2 mm but I still get the pulsating light when it is hot, after about 45-60 mins. First half hour it is rock solid. The light is pulsating at 1 hz between 100% and 60%. If I pry to limit the fuel with the knob it get solid again. Should I try with a smaller 350 jet? I wouldn't mind a bit less output if I get it to stop breathing.

 

Issues on pulsating can usually be resolved by inserting some heat resistant fibrous materials or sleeves along the entire length of the vaporizer's straight section. Examples of materials: bronze wool, solder wick, ceramic wool, copper wire strands, stainless steel wool, etc.

You can use a 350cp jet on a 500HK lantern. In this case, you also need to change the cleaning needle to suite. However, the jet isn't the cause of the issue here. Therefore, not the proper approach for a supposedly 500HK lantern.

 

Well pumping air into the tank will help too against pulsating. Most people forget that in the beginning the air volume is small (tank full) and will rapidly disappear.

 

I tried raising the pressure to 2,5 bars and that made the pulsating go faster and maybe with somewhat less swing, maybe 100-70% 1,3 hz instead of 100-60% 1 hz. What is the theory behind stuffing "things" in the generator? To slow transport of fuel? Is this a common thing or am I "lucky" to have this?

 

With higher fount pressures, the frequency of pulsation will usually increase, but with a somewhat lower amplitude. Sometimes, frequency gets high enough and with sufficient reduction in amplitude that it gets smoothered or evened-out to become a lot less noticeable.

The theory behind the pulsation phenomenon is quite involved or complex and still not entirely understood. It might require some further reading on some literatures.
Anyhow, it is something that had already been observed much earlier on these devices by various inventors of such liquid-fueled lighting devices.
There is a combination of various physical phenomena at play during the event.
There's something called the Leidenfrost effect when the liquid fuel is exposed to the very hot inner surface of the vaporizer. In that effect, the superheated fuel on the contact surface would be aggresively displaced and repelled in multiple directions within the vaporizer. This in part, disrupt the fuel flow and alter its direction in unpredictable patterns. It also disrupt proper or smooth vaporization.
The use of wide boiling range fuels like gasoline, kerosene, etc aggravates the effects further.
Another point is, at such elevated temperatures, the effective mass flow rates of vaporized fuel through the jet's orifice would be significantly reduced as compared to when it is in liquid form. This limitation restrict the amount of heat-expanded vaporized fuel through it. The total amount of expanding fuel still needs to go somewhere. In this case, the path of least resistance would be back to the fount where there is still a volume of compressible air in it.
When the expanding heated fuel is cycled back into the fount, it dissipates its energies to the surrounding cooler fuel and fount material. Here, it cools down and contracts again. The existing fount pressure again overcomes or balances out the earlier backpressure and the fuel direction is then returned to normal flow.
The cycle repeats itself at some frequencies depending on the various existing operating variables.

Stuffing, wrapping or inserting fibrous material into the vaporizer has several effects. Among them, it effectly reduce the total amount of fuel occupying within the vaporizer. Another, it alters the vaporization kinetics in a peculiar way that is not only limited to distributing heat more uniformly throughout the fuel volume with improved thermal transfer as well as an increase mass of additional material for heat storage within the vaporizer. With this, excessive locallized heating is averted.
In such a fibrous or porous medium, there is also certain wicking taking place. This distribution of fuel also alters the vaporization kinetics as compared to a solid volume of fuel.
In effect, the vaporization becomes somewhat more uniform. The stuffing also restricts backflow to some extents.
The reduced volume or mass of fuel residing in the vaporizer also allows a more complete discharge of vaporized fuel via the jet orifice without unnecessary expanded fuel being cycled back to the fount.

 

You can try some brass mesh/gauze rolled up and put in the vapouriser, I have had mixed results with this. I am not aware of anyone putting fibre packing in a Petromax vapouriser as I guess it might interfere with the needle actuator rod.