I have a very rare Chilean made F40T10 tube that I want to lit up, but it's EOL, and I want to give it a second life. What is the best way to extract extra life from an EOL tube? Should I run it on a bug zapper circuit?

How it si EOL? Lost emission (starter is flashing permanently) or has an open filament?

If the second is the case, you may use some electronic instant stsrt ballast, but have to look for the exac lamp specs (mainly the nominal arc current) first.

But I wont run it on any such low current thing, it will wear off the rest of the emission layer that still may remain there.

The tube have an open filament. I can't get an instant start ballast. There are some electronic ballasts, but there only are available for common lamps like T5s and circular fluorescents, and a T10 lamp is a rare standard, so the possibility of getting an electric ballast that is instant start for that specific lamp is none. I'll need to create myself a voltage multiplier that can operate the lamp close to the ignition voltage and the normal working current. But I don't know what capacitors and diodes to use and the currents and the ignition voltage of an F40T10.

What are the electrical specs? What ballast is used with it normally? Isn't it made compatible with something more common, like F40T12, or 32 or 40W circlines?
It does not have to beexact match, it just has to deliver something between 60..100% of the lamp rated current, and work with the given arc voltage.
Cheap electronic ballasts are usually possible to wire so it lights up even with one broken filament...

What happens if I bypass the open filament with a wire or a resistor of the same value of the filament? I saw a guy bypassing the filament with a siccor on a random lighting YT video. 

F40T10 lamps are designed to run on a standard F40T12 ballast.

A electronic instant-start ballast will light an EOL lamp (as long as said ballast has no EOL protection), but it will also fry the lamp to vacuum loss pretty quickly.

All these assume only one filament is bad:

If the ballast you're using is preheat/switch-start, you can bypass the open filament with a piece of wire between the pins, and it *might* light, or atleast blink...but don't leave it running in that condition.

If you can get a LPF F40 magnetic rapid start ballast, it should light the lamp at half-brightness (and this one can be left running). Just as is, don't bypass the open filament, or you'll fry the ballast's filament heating circuit! 

There are certain Motorola electronic F40T12 & F32T8 rapid-start ballasts that will light an EOL lamp in a non-destructive way, they're all discontinued now, but do show up on eBay occasionally. Again don't short/bypass the open filament (with any electronic ballast), or you'll fry the ballast!   

A F28T5 ballast will light a F40 just dim. A F45T5-HO ballast will light a F40 at around the correct brightness, but most T5 ballasts have EOL protection, and will either not light an EOL lamp at all, or light it for a second then shut down.

Many old fluorescents failed just because the filament material broke (usually due to some mechanical kick,...), but the emission coating is still good.
Then the lamp will work practically the full lifetime even when the filament is broken.
So all the detrimental factor shortening the lamp life still apply here (mainly regardi g the too low current accelerating electrode wear).


But if the reason is normal wear, where the emission coating get consumed first and the filament breakage was just the consequence, there is no way to light this lamp up without leading to the vacuum loss.

The tube have a little gray mark in the end of the tube, buy not much, so there's still emmisive coating remaining, and quite a lot. I'll try to bypass the broken filament with a wire in a preheat gear. Hopefully it doesn't blow up the ballast, the lamp or the starter at the first try. 

I bypassed the open filament with a 2 ohm wire, I turned it on a 40w preheat gear. I got flashes, the gear couldn't stand a stable arc. The glowing filament is the good one, not the one I bypassed, and it is glowing kinda incandescent, so it lost some emmisive coating.
GIF of the lamp working, flash warning!
I only let it run for a couple of seconds for not to fry my gear. How many hours will it last on a cold cathode circuit before reaching vaccum loss?

Here i've shunted an F6T5 lamp thats EOL to get it to start on preheat. I used a mini xmas lightbulb stuck into the socket pins.

That might work.    I'll try it now.

Edit: The xmas light bulb just went into a blue flash. 

What about running the tube in a CFL or similar ballast of the same power? The trick of bypassing the filament kinda works well. Maybe a 20w CFL ballast can do the trick.

I bypassed the open filament with a 2 ohm wire, I turned it on a 40w preheat gear. I got flashes,

Flip it around so the good/bad ends are opposite where you had them before & try again. Preheat can be temperamental/has something to do with polarity across the starter. 

How many hours will it last on a cold cathode circuit before reaching vaccum loss?

On instant-start, you can be talking a matter of minutes or even seconds. If the filament truly still has its emmisive coating, it could actually end up lasting quite awhile.

What about running the tube in a CFL or similar ballast of the same power?

its not so much about 'rated power' on the CFL, but what length the CFL would be if stretched out into a linear tube .and. what the rated current/voltage across it is.

The prehat circuit wont operate it, because tge preheat requires the electrodes to warm up before ignition. You need something able to start cold lamps.