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Topic: Best Choiuces for Sensing Fire... (Read 1 time) previous topic - next topic

pracas

How would you sense fire? simple and effective means for a bot i'm building... i'm planning to use the temperature sensor and wanted to know if there are other ways...
Be The Change...

RIDDICK

#1
Nov 19, 2008, 02:33 pm Last Edit: Nov 19, 2008, 03:18 pm by RIDDICK Reason: 1
hi!

i use a CO2 meter, that costs 90? (about 126USD)...
it delivers 0V (0ppm CO2) to 5V (2000ppm CO2) and takes 2500mW (max, at a supply voltage of 5V)...

1000ppm CO2 r ok...
2000ppm CO2 r a reason to leave the work place in some countries...
permanently >40000ppm CO2 (4%) r toxic... for "kiss of life" (first aid) 4% CO2 r good, because the breathing-center feels stimulated then...

http://en.wikipedia.org/wiki/CO2#Toxicity
http://en.wikipedia.org/wiki/smoke_detector

u should ask the local fire fighting authority for assistance...
in the USA fire detectors might be subject to legal regulation...

bye
arne
-Arne

kg4wsv

Someone makes a pyroelectric sensor array (1x8 pixels, IIRC) for about US$100 that sounds ideal for this application. (pause while Jason digs through his junk)  Ah, here we go, model number, web site, and sample code all rolled into one:

Code: [Select]
// prototype code for interfacing Devantech TPA81 thermopile array
// http://www.robot-electronics.co.uk/htm/tpa81tech.htm
//
// Jason Winningham
// 27 june 2007

#include <Wire.h>
#define TPA81ADDR (0xd0>>1)

void setup()
{
 Wire.begin();        // join i2c bus (address optional for master)
 Serial.begin(9600);  // start serial for output
 Serial.print("starting TPA81 test\n");
}

void loop()
{
 byte b;
 int i;
 
 for (i=1; i<=9; i++)
 {
   Wire.beginTransmission(TPA81ADDR);
   Wire.send(i);
   Wire.endTransmission();
   
   Wire.requestFrom(TPA81ADDR, (int) 1);

  while(Wire.available() < 1)
  { ; }

   b = Wire.receive(); // receive a byte as character

   Serial.print(b, DEC);
   Serial.print(" ");
 }
 Serial.println("");

 delay(2000);
}


There are also single sensor pyros that may work.

A pyroelectric sensor measures the temperature of something remotely, without making contact.  They're usually the sensor in an "infrared" thermometer.

-j


kg4wsv

#3
Nov 19, 2008, 03:43 pm Last Edit: Nov 19, 2008, 03:43 pm by kg4wsv Reason: 1
Quote
fire detectors might be subject to legal regulation..

Wow, on the surface that sounds really stupid, like the result of an incredibly socialist government and/or union influence on the government.  Why would one make a smoke or any other fire detector difficult to get?  Hopefully you don't live in such a place and know this from personal experience.

Thankfully there are no such restrictions on getting the sensors here in the US (although idiots in NYC are heading that way with radiation sensors).

Riddick's CO2 sensor gave me another idea, though: get a standard smoke detector (US$10 or so, IIRC) and tap the light or beeper line for detection.

-j

RIDDICK

Quote
Why would one make a smoke or any other fire detector difficult to get?


hmm - the argumentation goes as this:
when it is said to be a smoke detector, people in the "sense area" might feel safer than they really are (e. g. because the smoke detector died 2 years ago when the battery failed)...

I'm no native speaker... sorry if i use misleading words...
here is my source:
http://en.wikipedia.org/wiki/Smoke_detector#Batteries
this
Quote
public information campaigns have been created to remind people

was saved in my brain as "legislative means"... :-)
-Arne

drone

Quote
Wow, on the surface that sounds really stupid, like the result of an incredibly socialist government and/or union influence on the government.  Why would one make a smoke or any other fire detector difficult to get?  Hopefully you don't live in such a place and know this from personal experience.


They certainly are subject to some sorts of regulation, considering an estimated 80% of the ones in home contain radioactive material.  I think the context of the original post is somewhat different than what you're thinking.  They're not regulated such that they are hard to buy (hardly, I can get one at any home depot in 5 minutes or less), but that they must be made to stringent standards if being sold to the public.

!c

pracas

#6
Nov 19, 2008, 04:15 pm Last Edit: Nov 19, 2008, 04:19 pm by pracas Reason: 1
Well i live in perhaps a huge democratic republic where the fire department doesnt have the time to bother about an hobbyists fire fighting robot... unfortunately neither does the hobbyist have a budget of 100$... i figured out i can buy 3 arduinos for that cost might be even 4!... any cheaper choices around?

Should i be able to build one on my own using these...
http://www.glolab.com/pirparts/pirparts.html
Be The Change...

kg4wsv

Quote
I think the context of the original post is somewhat different than what you're thinking.

Very well may be.  I apologize if I sounded harsh or critical, especially of Riddick, as that was certainly not my intent.  I just immediately thought of the efforts in NYC to ban the possession of radiation detectors, which I consider to be the height of stupidity (and stupidity really annoys me).


Quote
neither does the hobbyist have a budget of 100$

I thought they were expensive myself.  I wondered if they were designed for a specific type of competition (e.g. the IEEE SoutheastCon robot competition a few years back was a firefighting robot).

Quote
Should i be able to build one on my own using these...

Those are the sort I was thinking of, but not having used them myself I can't say for sure.  I personally would try one of these before I tried a $100 model.  :)

-j


RIDDICK

Quote
I apologize if I sounded harsh or critical, especially of Riddick, as that was certainly not my intent.

no problem - i found it funny... at work i had to attend a "1hr" (on my watch 2hrs, but i'm no "doctor of chemistry") network shutdown, because some officers of the state wanted, that we use "10.X.X.X" IP-addresses in our private network (and no longer IP-addresses, that r assigned to their agency) back in 2000.  ;D

Quote
Should i be able to build one on my own using these...

ok - this 4USD-sensor (plus lense or plus a radar-like device) looks sweet and possibly does what u need...
-Arne

pracas

Unfortunately i do not live in the US of A so i gotta go shop by shop searching for it this weekend. Will keep u guys posted if it works.
Be The Change...

kg4wsv

While shopping in Lowe's (home improvement warehouse type store here in the US) I found some motion activated light sensing LED lights on the clearance rack for US$0.75 each.  I bought them all.  Inside each one was a pyroelectric sensor, a photosensor, a bright white LED, and some other stuff.

Haven't used them yet, but I knew they were pyros and I may use them for something one day. :)

-j


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