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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

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