Coleman 226 fuelling

@M4v3r1ck @Dashwood
Modification completed, sleeve soldered over the air inlet hole in the outer concentric tube.

NB The O-ring seal hadn’t hardened and broke removing it, but I replaced it anyway and reassembled the pickup to valve body with thread sealant to be sure. A perished, perhaps hardened, O-ring would surely result in an air leak contributing to pressure loss in the tank, so (with hindsight) should have been the first thing I should have checked.




Fuelled with white gasoline and not kerosene for now, the lantern lit easily well before the spirit cup’s flame had died down and was still running after an hour-and-a-half without additional pumping when I decided to end the test firing.







I fired up an early 222 I have (metering needle in the pickup inner tube equipped) and brightness and certainly duration of running time were comparable. The 226 responded appropriately to the ‘low’ setting of the control knob incidentally.



The only small inconvenience arises in filling the spirit cup and lighting the alcohol. This can fill it …




… but getting a flame near enough to the spirit to light it is difficult. It didn’t take much effort though to remove the lantern hood, fill the spirit cup, apply a light and replace the hood and bail.

 

Something to be aware of: with the "lower collar" removed, your fuel pickup is slightly higher, and you'll start sucking air before the fuel is all gone. With the sleeve soldered over the air aperture, you *should* be able to leave the lower collar on, to lower the pickup point, without it adversely affecting the burn behavior, in any way.

Great news about the air-efficiency gains, though!

 

Yes, I anticipated that, but I reasoned that I’m unlikely to run the lantern to drop the fuel level so low. Without replacing the inlet tip component I could solder on a sleeve resembling the one I used to cover the air inlet. I’m reluctant to rely on the pinhole inlet to reliably pass sufficient fuel. Without the metering rod (and its pricker function) of a conventional Coleman FA pickup and having a much smaller orifice it is likely to be prone to blockage.

Fuelling with kerosene, lighting was as straightforward as with white gas, combustion just as good.

 

Valid points. I have to wonder how hard it would be to add the metering rod. Drill a hole in the center of the bottom of the eccentric block, solder in a section of brass rod (assuming eccentric block is steel or similar), and bore out the hole in the lower collar. Notch the brass rod, based on eccentric block travel, and hooray.

Very interesting that it runs happily on kerosene.

 

@M4v3r1ck
It’s possible, I’d say, and even without the fuel metering aspect of the rod, it would be beneficial to have its ‘pricker’ function to keep the inlet orifice clear. A tiny pinhole in the existing arrangement is surely asking for trouble unless clinical standards of fuel filtering on refilling are observed, together with a scrupulous maintenance of the cleanliness of the fuel tank interior.

The eccentric block in my example is non-magnetic and more in the mazak than steel spectrum, so securing a metering rod in it would have to be by mechanical means of some form.

 

Still possible, with something like rocksett, high temperature sleeve retainer, or, if that fails, high temp loctite and a threaded interface. Sure, it's violating the "purity" of the device, but as you've noted, nobody really likes the way the later ones behave, so why not?

 

Well said.

 

Hi folks.
I'd like to add to the confusion in this topic.
My wife gave me a 226 for Christmas many years ago and I had the same problem with overly air consumption and consequently pressure loss. I had to pump it up every 15mins and haven't run it for a long time now.
According to my understanding and comparing this pick-up tube with others with the inner rod I had read that in a static situation (e.g. lantern not burning or fuel level changing very slowly during operation) the fuel level in the fount and the pick-up tube should be the same.
In case of a lantern with an internal rod the fuel delivery is very limited during start-up (rod almost completely blocking the pick-up hole), thus generating a very meager mix with very little fuel and much air. At least when the little amount of fuel inside the pick-up tube is vaporized, the meager mix should exist. When the mantles burn and the valve is set in the open position the rod is retracted and the pick-up tube hole fully opened. Then the mix is rich, i.e. only fuel will be pressed up without consuming air from the side hole. This works as long as there is enough fuel going up and the fuel level is kept equal inside and outside of the pick-up tube, thus avoiding air being sucked down from the side hole. This is the key point in my opinion.
If this is correct, then the relation between fuel delivery from the pick-up hole and air from the side hole is not in order in the 226 during operation and fuel is not provided in the neccessary amont to keep the fuel level inside the tube constant. In that case the missing fuel flow is compensated with additional air.
My conclusion?
I think that a minimal (!!!) widening of the pick-up tube hole would allow more fuel to rise, keep the fuel level inside the tube constant and avoid air being drawn from th side hole. This must of course be done very carefully, perhaps with even some very careful step-by-step approaches (or quickly open and close the main valve several times during start-up thus avoiding flaring up).
I'm not sure how this will influence the start-up procedure but I think it's worth a test. If it worsenes the start-up one can still use a sleeve like Tony has put over the side hole and preheat with meth. spirit.
So far my theory. I haven't fiddled with my lanterns lately but I'm interested in your opinions.
Thanks, Erwin.

 

@Erwin

It's possible that the pickup orifice is insufficient to keeping the pickup adequately filled during operation. Vapor is being consumed at a rate that the pressure is skirting at the limit of what the pickup can replenish so air is being consumed as the pickup runs near being dry.

Additionally, on a full topped off fount, air pressure at prime can be extremely high vs what's encountered in other larger lanterns due to volume, enough to bypass and defeat the pickup regardless if there's pressure inside the generator controlling the flow of fuel.

The oversimplification of the FA system is not ideal for small volume lanterns.

 

@Erwin That's exactly what I was suggesting in post #25. It absolutely would work, but the needed lower aperture to maintain *just* fuel flowing up the inner tube would grow, as fuel level in the font got lower (reduced pressure head, resulting in reduced flow through the aperture)

 

@M4v3r1ck

What I also know and I'm not sure if you found out is the 222 pickup metering rod works differently than your standard metered pickup on the larger lanterns.

On the larger lanterns, at operation, the valve is fully backed out which releases the metering rod via spring tension. This uncovers the pickup orifice which quickly fills with fuel and replaces the air flow with fuel to feed the generator provided there's sufficient vapor pressure to keep the pickup replenished.

On the 222, the spring is entirely absent and the metering rod is incorporated directly onto the eccentric. As a result, an addition is made to the rod itself which is a grinded down flat section which I will explain shortly.

At close, the eccentric is fully depressed with the metering rod protruding out the bottom of the pickup, and the annular space is sealed by the oring around the eccentric preventing fuel flow.

At the lighting position, the eccentric is lifted by cam action of the knob unseating the oring and permitting flow. Since the knob is nearly at the 12 o'clock position the highest position on the eccentric, having the metering rod fully unseat will prevent the fuel air circuit from working properly and will quickly flood the lantern with a massive flareup. So in essence the metering rods function almost in reverse. The rod is engineered to be further lengthened so at the lighting position, the rod obstructs the orifice enough to permit proper operation of the instant light function.

Now finally at the run position, the lantern is sufficiently heated and primed and is ready to ingress straight raw fuel from the fount but as you can clearly see at the run position on the knob, it appears to have almost done a 180, clocking away from the 12 o'clock position, you'd assume this won't work because now you're just depressing the metering rod and still block fuel flow needed for normal operation. Here in lies the addition coleman made on the metering rod, a grounded out flat section that when inside the oriface, allows fuel from the unobstructed section of the rod, allowing sufficient fuel flow to replenish the pickup despite the presence of the metering rod inside the oriface.

 

@M4v3r1ck, I don't think the reduced pressure makes a diffenrence since it would reduce the pressure inside and outside alike. Hence the liquid level is kept equal. The lantern just goes dim.

 

I'm not talking about the static pressure (air pressure in the font). I'm talking about the head pressure. The difference in height between the fuel level in the font, and the bottom of the inner tube, which, times the density of the fluid, gives a head pressure. The flow across the orifice in the bottom collar introduces a delta-P, which draws down the fuel level in the "main well" between the inner and outer tube. If THAT fuel level gets low enough, because the delta-P across the orifice is larger than the head pressure from the fuel level in the font, then the air will start rushing in the bottom of the inner tube, drawing some liquid fuel with it, just like the "factory" 226 does, but at a lower font fuel level.

 

@M4v3r1ck

I agree with your assessment. Depending, if the fuel well inside the pickup is unable to adequately replenish from such small pickup orifice, the air will start to encroach into the inner sleeve regardless of fuel level. It will behave as if the starting circuit was always on. The backpressure from the vapors in the generator isn't sufficient enough to let the pickup remain filled.

You can demonstrate this pressure loss on a normal 220 lantern for example. By keeping the valve in the 1/4 turn position and you will notice the lantern will slowly start to dim as air continuously mixes into the fuel stream since the pickup is obstructed and is unable to keep the pickup filled. And the pressure also drops faster.

I have witnessed the lantern running low on pressure in as little as 15-30 mins if I kept the valve cracked at 1/4 turn vs fully seating out.

 

Having written this …

… and subsequently established on removing the end cap and taking a closer look at the inner tube’s top fixing that I was wrong, I produced a revised - and this time hopefully correct (!) - schematic drawing for the 226’s fuel/air pickup.

 

@presscall yes, your drawing is correct.
And knowing that setup, which just relies on liquid and gas dynamics, and the volume increase of vaporized fuel,
lets us understand, how fragile this balance is, for good operation and easy startup.
As this fragile balance most often tilts to the wrong, undesirable side of quick air loss, i closed air intake hole in my problematic 226 lantern.
It needs preheating since. But keps air pressure longer.

 

Please does anyone have the diameter of the atomiser hole at the bottom of the FA tube? I can't see it mentioned anywhere above. This has been an interesting thread.

I will not modify mine since it is great for ease of lighting and I don't need a long burn out of it.

I have never checked that hole is clear, which it might well not be, given that my original vapouriser was blocked by corrosion and had to be replaced.

 

Sorry for the delay in replying.

Yes, a 0.18mm diameter acupuncture needle only just passes through it.

 

Thank you John. @presscall Just what was needed.