Hey, I'm going to try to make this short and sweet since I'm in the middle of preparing for exams atm,,
I've seen a couple of things I'd thought of floating around here (and sorry if I missed some I may have skimmed some of the posts) and would like to give my thoughts on them (some of these ideas may not have been posted yet).
The current situation: extinguisher (reactive) chemspray (proactive)
In gameplay I find that the extinguisher does its job well, you see fire, you go over and then spray it, the fire goes away, you go back to something else until the fire gets too high again (possibly waiting the 3s to give a hammer whack as well). You react to the fire.
The chemspray kinda does its job, but it does it in a really awkward manner. If you want to protect your ship (even only the critical components) you're going to be spending most of your time running around like a crazed hobo spraying left and right trying to keep up with the 20 second duration. Not to mention if you want it to be truly preventative (proactive) you have to start doing all this, and keep doing all this, while absolutely nothing is shooting fire at you yet, because if you wait for them to be almost in range of your ship, you won't get to spray the components in time, not to mention you'll have started taking regular damage from other sources and that shit needs fixing(cooldowns), and you have ships to spot and stuff to buff... And oh boy if someone decided to whack the hull with a mallet just before you could chemspray it, and all those firestacks are rising up... it can be kinda infuriating.
What I don't like in theory about the current chemspray is it's nature as a hard-counter to fire damage. The full immunity is, as has been mentioned by others, an all or nothing kind of deal. Either it completely negates the damage and disabling from ships like a double-flamethrower squid, or it just doesn't function (not compared to the extinguisher at least). My biggest problem though is that it lacks any real counterplay if it's good. If the chemspray works properly with full immunity, the opposing team has no way of knowing what you've sprayed (if they even know if you've sprayed it) and thus can't work around it (unless they just have other guns to fire, but that's besides the point).
If full immunity is an adamant requirement however, simply reducing the cooldown on the chemspray and/or increasing it's duration should work fine to make it viable.
Now OTHER options include, but are not limited to:
1. Chemspray lasts WAY longer but gives only a % reduction in chance of firestacks
2. Chemspray lasts WAY longer, and negates firedamage, but doesn't stop stacks from being applied.
3. A combination of the above, where it reduces the % stacks applied and damage done while active (but not fully negate either)
4. Chemspray removes firestacks over time (possibly in combination with any of the above) with the possibility of continuous spraying removing stacks faster (either directly or by increasing the strength of the buff)
The first option is pretty viable, assuming the cooldown on chemspray (or extinguishing power) becomes good enough that you can remove what stacks got through the buff after the fight is over, but for it to be effective without compromising the "proactive" quote you would need such a high percentage of reduction that it might as well be immunity.
The second option I dislike alot, because it essentially requires you to have an extinguisher, or keep the buff up indefinitely (not to mention it once again completely negates firedamage going through, which feels shit to play against)
The third option I'm allright with, it allows your opponent to get some firestacks through and do some damage, but alot less than they otherwise would, and refreshing the buff should remove enough stacks for the total damage reduction to be comparable to the extinguisher. I feel however that it would do better combined with the last option.
The fourth option is my favorite, because it is entirely proactive, doesn't completely negate flamethrowers, and depending on the specific implementation can "if done perfectly" entirely negate firestacks (which is ofcourse impossible in practice). The main reason I like this idea is because it allows the engineers to spend time doing other things (like repairing the buffed stuff or shooting guns while the buff takes care of the fire-stacks as they pop up) because they applied it beforehand. It has a "good job" proactive feel to it. The way the other flame-retardants work is either you don't see any firestacks pop up at all (did your buff even contribute anything?) or you just see less stacks popping up (was the chemspray worth it, or would I have been better off with the extinguisher?) where as this gives direct feedback that it's working (I can see the stacks go up and then get removed by my buff, I saved time extinguishing now by spraying earlier!)
well that was probably longer than I intended but I hope it contributes something, time to get back to learning