That is why all well-designed projector spoolboxes are not airtight, but have an 'lip' directed away from the operating side of the projector so that the flames don't hit the projectionist in the face. As an added precaution, restricting the amount of film per reel to 1,000ft will limit the amount of toxic fumes generated if a reel goes up. With adequate air extraction capacity in the projection box, enough of the fumes will be sucked out to prevent the projectionist from being overcome before he or she can escape. But all this depends on the projectionist not attempting to fight the fire and following the rule that John and Joe have both stated: get out, then let it burn out.

As for the wisdom of attempting to project nitrate at all, I wrote a paper about this when I was a film archiving student. Having spoken to people at all the cinemas in Europe I could find that still do it (a grand total of four, two of which are archive preview theatres), the rules which everyone follows are:

1. Don't do it if the print shows early signs of decomposition (i.e. if it is sticky).

2. Don't do it if the print is significantly shrunk. The NFT used a 'shrinkometer' gauge to measure linear and width shrinkage, and up to 5% on either was considered acceptable.

3. Don't do it if there is any significant perforation damage.

4. Only project 1,000ft reels at a time. If necessary split up 'double' reels and add leaders, tails and cue marks as needed.

5. Never, ever attempt to project a preservation element. The only nitrate prints suitable for projection are 'surplus' nitrate release prints acquired by an archive, i.e. better quality elements and of a closer generation to the camera negative are already preserved.

If all these criteria are satisfied and in a box with the proper safeguards (spoolboxes, adequate air extraction, fire shutters on the ports, at least two separate exits from the projection box leading to different parts of the building and a separate storage area for the nitrate reels with a fire resistant door seperating it from the main projection box), then you can do it.

There was a part in the film when he was teaching Toto and he said that if the film caught fire you could take a pair of scissors and cut the film. (Ostensibly to keep the fire from going up into the magazine.) Although that makes sense, logically speaking, it just seems pretty darned unrealistic to me.

If the nitrate film caught fire in the projector and sound head, the rollers would quench it before it spread to the magazines.

Hydrogen Peroxide was used to clean up the mess in the projectors and soundheads. But, if it spread to the magazines, you tripped the porthole shutters on your way out of the booth.

They had a common trip - usually by the exit door. You didn't have too much time to get out. The fumes were very toxic.

I think some booths had heat fuses to drop the steel shutters in the portholes in case the projectionist could not get to the main ripcord.

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The lack of parameter rollers around the pay-out head = a disaster looking for a place to happen! I forgot about those sytle platters. You would think by now a retro-fit kit for those machines would be available.

Personally, I really never really believed in those wrap detectors. Most of the wraps occur because of improper threading, the tail came loose and snagged the pay-out, or a sticky film or a shitty splice doubled up and sucked itself through the payout head as well as a button or switch being in the wrong position. And, true - some designs leave a lot to be desired.

Of course, equipment failures do happen, but I don't think (percentage wise) it is the main cause like everyone says it is. As with any piece of equipment, it will fail if abused, neglected, or operated outside the machine's specifications.

Yes, Gordon - Carbon Tet is some very nasty stuff! Supposedly, it is illegal in the US, but I don't know about other countrys.

It did as you say...as the tension increases, it would draw a blade across the film (like scissors) to cut the film as it entered the projector.

Better designed "wrap detectors" use a "yo-yo" system like on the take up so the projector can run down without increasing the tension. Neumade, Big-Sky and SPECO have this type of sensor (and probably others). Another big thing to remember is to have the wrap detector shut the automation down...some are designed to merely turn off the take up platter so when the take up roller drops (or runs out) the normal failsafes will take over....the problem is, in a high tension situation, the take up roller won't drop.

Steve

On the other hand, if you decrease the strength of the magnet you'll get shows stopping unnecessarily.

This is why I feel that a cutter might be a better solution. The kind of thing I have in mind is an assembly which sits on top of the platter tree consisting of a motion detect roller and a spring-loaded cutter blade held back from the film path by an electromagnet. If the motion detect roller says no motion, then power to the magnet is switched off (as well as power to the platter and projector) and the film is cut as near as possible to the feed unit. That way you'd relieve the pressure caused by the projector mechanism pulling at jammed film straight away.