So I ran out of petromax mantles and only had the midstate lighthouse branded no. 625 mantles and while it filled up beautifully, my main concern is the final size it has after firing. Should I worry about possible overheat?
No you should not. Use the correct shape and size (CP) the brand is of no concern. Quality aside. In fact the flamefront or flameshape will form the mantle. Other fact is how the mantle folds are distributed around the burner head. What would be overheated or overheating do you think?
At 2.5 to 3 bars. Shutting it off reveals parts of the inner case and J-tube glowing a dull red. At 2 bars, it's less apparent and only the nozzle glows.
When alight for some time metal part get hot yeh, but that is ok. Nothing to worry about. When the tank gets dull red then it is time to start running.....
Seems a bit high to me. You should only pump until the maximum brightness is achieved. More pressure would only result in higher fuel consumption, noise, and wear of the mantle. Most of my lanterns run properly at 1 - 1.5 bars, although you can't really trust the gauge readings. After all, they are only guesstimates. If the pressure drops too much, the flame is too small, which causes the generator to cool down and it therefore spits out liquid fuel from time to time, resulting in short bursts of flame with corresponding clouds of soot.
Petromax literature indicates 2.0-2.5 bar (the line between the 2 and 3) is the normal range of operation. I read someone tried to do 3.0 on their 502 automatic and was able to exceed the advertised CP rating (500cp) with a professional light meter (around 580cp). Luck of the draw it seems during the gathering with other petromaxes falling short (400 on average, seen some as low as 350).
The Midstate Lighthouse #625 mantle does not seem to be too large for your Petromax. Basically, there should be no overheating concerns from this alone. The more worrying part would be the extent of the J-tube's glowing. At most, only the lower end near the ceramic burner should be glowing from normal operations. Anything more extensive would be damaging to the J-tube. You should check if there is any flame outside the mantle, indicating a worn jet/gas tip or other anornalies. In some instances when you are operating the lantern with a higher-than-normal pressure range, a slightly worn jet can produce a somewhat higher output(visually brighter than the usual ratings) without indicating a rich burn or producing any sooty leftovers. For the unwary user, this can certainly overheat the lantern parts by excessive heat output. Not sure if this applies for your lantern here.
Can you share this source? As far as I recall the red line should be 2bar and is the operating pressure according to H. Lahde. Only minus point is that it often is more an indicator then a real gauge.
On a 500cp hipolito and Px the red line is just under two bars. On a similar size Optimus I seem to recall the instructions are 40 pumps to light going to 60 once lit. Different if using the rapid. Number of pumps of course being reliant on the airspace volume in the tank, pump condition etc
It's written in the current manuals that came with my modern petromax and I believe in my older one that came with my 1965 Pmax also states this. I'd have to check.
The red reference line on the attached gauges usually points to a pressure indication around ~30psi, ~2bar, ~2kgf/cm2, etc on Petromax-styled lanterns. To be honest, these are seldom accurate as gauges.
The manual downloaded from PX website today says 1.5 bar. So pushing it to 3 bar might give you your answer to glowing parts ?
Ha - so it does -all these years I have been using the red line (apprx 1.8bar) - I do not use the rapid start habitually.
