Detecting Perforation

[ric_vas]

Hi,

I need to provide a solution to detect a perforation (e.g. drill hole) in a box (metal) when it takes place. Currently I have a external structure with wires that covers the whole surface. Works similar to a fuse but it´s hard to install it.

Has anyone done something for this purpose?

Thanks in advance.

Ric

 

[kak111]

Tell a bit more about this problem....
-the basic purpose of the device is .........???
-surface area to detect
-vertical or horisontal
-diameter of hole
-if many holes , distance of holes, number of holes per detect area
-size of detecting device
-what to do when hole is detected
- others........

 

[ric_vas]

Hi!

You can think the box as a safe, let´s say 600x600x600mm and this part is to detect intrusion. If a hole is made on it I'll fire an alarm. Today I have this bunch of wires tailored over a piece of tissue and glued over the box. Like a huge mechanical fuse.

Hope this helps.

Thanks.

Ric

 

[kak111]

Can this "box" be air-tight,
so we can put very low overpressure on it
and detect any air leak.
Or it is solid piece, with your wirenet sensor on its external surface

 

[luben111]

Hi, there is a new technology for touch screens where >= 2 micron copper wires are placed on plastic (PET). They grow the lines on some substrate (contaning paladium). So if you make a serpentine (a single wire running zig zag) and you place the wires 0.5mm away from each other you could have a sheet of PET any size which will 100% detect perforations with diameter bigger than 0.5mm. If there is intrusion you'll see dramatic change in the resistance. Probably the idea is patentable (or "was" patentable before I post it here).

Of course you can print the wires with conductive ink on PET as well. The idea of the wires is not bad, it's just a bad idea to handle the wires manually. If they are embedded into PET it's different story.

 

[ric_vas]

Hi!

First of all, thanks for your replies.

kak111,

The box is not solid, neither hermetic as well. Not sure how to handle pressure inside it.

luben111,

I´ve already tried to substitute my tailored wire structure. My first though was build it like a membrane keyboard with silver based conductive ink, but that´s got to expensive. Would be that the same case?

Regards,

Ric

 

[luben111]

>>My first though was build it like a membrane keyboard with silver based conductive ink, but that´s got to expensive

I'm afraid that it could be even more expensive.

From other side the pressure is not detecting the integrity of the box but detects how is sealed the box which is slightly different. Until the pressure is constant even if the box is drilled we will not detect anything. For sure pressure is the easiest way

 

[kak111]

Here is principle for sensing "hole in the box"
Use very low pressure level , it depends on differential switch you use.
Set flow level so low , that system can detect smallest hole you will detect.
Note that box air volume act as capacitor ie. system has time delay on detect pressure drop.
You can minimize this time constant by decreasing volume by using
air-tight "hollow" plate instead of cubic box.

 

[erikl]

... detect a perforation (e.g. drill hole) in a box (metal) when it takes place.

What about coating the surfaces with a sheet of paper (or plastic foil) double-side laminated with a thin metal foil (Al, Cu).
During drilling a hole, both metal foils would be short-circuited.

 

[ric_vas]

erikl,

That sounds intersting!

I'll think about it and check how can that be assembled in this case. I´ll Get back with more info.

Thanks,

Ric