New project: Fire sensing laser cut out system - and maybe more later.

[Bill George]

Graham I did finally get a hold of some people with prices on the Honeywell Fire Sentry FS24X and the price is nearly $2K or so. I'm sure it could be had for a little less if you got a hold of the right people. Its still out of the hobby laser or sideline business laser acceptable price range. By the time you got the rest of the system up and running it would be double that.

[Graham Facer]

Just an update. You may have seen my other thread about issues with my old tube and then with my new tube. Needless to say this project is on hold until I am am capable of starting a fire with the laser again. And likely when its winter again.

Summer just doesn't lend itself to projects like this. But on the plus side, I finally got my batch of 25 flame sensors to rig up and do a large test and my valve solenoid - though I got 24v not 12v - but that might work with the control power supply for now. The valve would control the CO2 flood in the cabinet.

[Kev Williams]

I didn't thoroughly read thru this thread (don't have time!), but here's my 2 cents...

I've had a few fires...

One, I had a nitrile glove hanging down into the cabinet from the side, which ended up in the X-path of the beam when the gantry got down far enough...

I've also had a few transfer tape fires. Always from a piece of loose tape, never from well-stuck tape. Usually the blower extinguishes the flame. Sometimes the blower creates a really fast smolder...

...But the common denominators in my fires have been the same:

1--While shutting off the laser would prevent further fires, it will do nothing to stop the existing fire--
2--Shutting off the blower would probably do more harm than good--
3--Whenever ANYTHING is on fire, ash and burning debris gets sucked up by the blower...

Ergo--

1- shut off the laser AND add a VERY LOUD ALARM--
2- Do NOT shut down the blower-
3- If some sort of flame detector is to be installed, wouldn't it make sense to install it within the blower hose rather than the laser cabinet?

[Scott Shepherd]

I didn't thoroughly read thru this thread (don't have time!), but here's my 2 cents...

...But the common denominators in my fires have been the same:

1--While shutting off the laser would prevent further fires, it will do nothing to stop the existing fire--
2--Shutting off the blower would probably do more harm than good--
3--Whenever ANYTHING is on fire, ash and burning debris gets sucked up by the blower...

Ergo--

1- shut off the laser AND add a VERY LOUD ALARM--
2- Do NOT shut down the blower-
3- If some sort of flame detector is to be installed, wouldn't it make sense to install it within the blower hose rather than the laser cabinet?

That was my experience with a fire as well. #2 especially. It was the blower pulling the flames sideways that helped keep it from being a tall flame that burned up lots of stuff.

[Jeff C Johnson]

I know I'm 6 years late coming to this thread, and I briefly scanned the past posts, but I'm wondering if the easiest solution would be to have a thin cable that is in the gantry that when it burns, it breaks the connection. No guarantee that it would happen in the right place, but most fires that I've seen start around the head which is attached to the gantry. Then just break the door panel switch connection to turn off the lasing and dump a bunch of CO2 in there (not extinqhuisher, but a large body of CO2 in a 4 inch PVC like a potato gun. And of course an audible alarm. No substitute for watching the unit of course.

[Graham Facer]

I know I'm 6 years late coming to this thread, and I briefly scanned the past posts, but I'm wondering if the easiest solution would be to have a thin cable that is in the gantry that when it burns, it breaks the connection. No guarantee that it would happen in the right place, but most fires that I've seen start around the head which is attached to the gantry. Then just break the door panel switch connection to turn off the lasing and dump a bunch of CO2 in there (not extinqhuisher, but a large body of CO2 in a 4 inch PVC like a potato gun. And of course an audible alarm. No substitute for watching the unit of course.

Well I abandoned this project. I've found recently my almost fires have been junk on the knife blade edges that catches fire with prolonged exposure to a cutting flare up. Then it drips on to waste underneath.

So yeah decided supervision is the main part.

Graham