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Crawling Through Ventilation Shafts


In many a good action thriller movie we are taught some fundamental universally accepted facts about ventilation shafts, ducts, and their use for the purposes of crawling along, to escape or to gain access to another part of a building. Here's a brief summary about ventilation systems in movies:

* All ventilation shafts and ducts are accessible by means of a single flat metal grille which is held on the wall using four standard screws, all of the type with a slot, one at each corner. These are always loose and easy to undo, after which the grille plate can be removed and placed alongside the gap.

* All ventilation systems have ducts which are the right size for people to crawl along. There are no funny curvy bits, sheer drops, fan blades, rat grids, etc.

* Although it's a ventilation system, the air flow system will not be turned on while you are using the tunnels as a means of getting from place to place. Air flow, wind, noise, or any kind of suggestion that you're inside the pipes of a vacuum cleaner, will not be a worry, and you'll easily be able to continue with the script (though speaking quietly so your enemies can't hear you talking).

* All ventilation systems lead somewhere, usually somewhere useful. Fortunately, even though you had to undo the four easy-to-open screws on the duct by which you entered the ventilation system, the grille on your exit route will almost certainly have had the screws removed in advance and will come off easily so you won't have the problem of being on the wrong side to undo the screws.

* All ventilation shafts are well lit. No-one's quite sure why, but it may be similar to the way space helmets in many science fiction movies are lit up on the INSIDE!

* All ventilation shafts are CLEAN. Despite the fact that your computer power supply fan has dust stuck to it even after owning it a few months, these human-sized ventilation systems are spotlessly clean.

Speaking from my own personal experiences of crawling through ventilation systems, with some of my adventurous friends, while at university, I can tell you that the reality is rather different from that presented in the movies!

The first thing you notice when adventurously doing some indoor potholing is how dirty it all is. Ventilation systems, even in a clean building, are almost unbelievably filthy, with dirty greasy muck and thick biohazardous dust, the grime plastered along all surfaces untouched for years. It is hilarious seeing how clean the ventilation shafts are shown to be in movies!

Although ventilation systems lead somewhere and there's scope for using them as a route to get from place to place, there is generally a "business end" with some kind of motor, which you want to avoid, and also the shafts and ducts have been put in for air, which doesn't mind going vertically up and down, so it is more likely than not that the route may be somewhat inconvenient, with some vertical bits in it. My fellow adventurers and I agreed that we'd not hang a rope and climb down a 60ft shaft that was discovered behind something in one of the bathrooms in a tower block, as the danger was probably not compensated for by whatever discovery lay at the bottom of the shaft, (probably the fan motor).

Most ducting in the building was too narrow to be navigable, but it was found possible to get into some of the larger sections if you knew where to gain entry. There were some interesting unexpected discoveries, including a whole floor of plant machinery (floor two and a half), and a spare lift shaft which had never been used and had never had a lift and winding gear in it, but a continuous current of air was always ascending.

Other people I know who have travelled around inside the service tunnels in buildings report catching mysterious illnesses which the doctors can't identify and just pass off as "oh, it's a bug that's going around". For this reason and because of the dreaded MRSA scare, I advise against travelling though the ventilation systems in hospitals!

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Also see other Common Mistakes in Movies, which also includes things to do with fire sprinklers, gold, cats, and a variety of other odd things.