Worthwhile and cheap fire safety device.

With a lot of help from fellow forum contributors [forums.reprap.org] I have put together a simple, cheap system to provide a little backup safety in regards fire. Diagram included.

This system shuts off the power to the printer when smoke is detected and it stays off until you manually reset it. I have not extensively tested it, but in response to blowing some cigarette smoke (electronic) over the sensor it triggers and shuts down the printer. It will work with any printer (up to 10A 240v mains supply, if your PSU draws more than 2A then beef up the momentary mains switch as the one I used is only 2A rated) so long as there is a place to attach the smoke detector, preferably above the print head/electronics or at the top of an enclosed print area.

Whilst this system has one detector, It should be possible if you want to install several detectors to connect the smoke detector relay outputs in series so if either one triggers (opens a NC contact) then the power goes off.

I have not had a false trigger yet but its sensitivity is adjustable. I do not know how reliable this device is but for $20 it seems very worthwhile.

The parts needed are:

-Smoke detector (optical) - DYP-ME0010-A (amazon/ebay/aliexpress)
-Voltage regular 9v 1A LM7809 (available almost everywhere)
-Power relay module [DC 9V 10A 2CH High Low Level Trigger Relay Circuit Module] (ebay) there are other types that will do this job, this unit just seemed easy and has LED's to indicate its status.
-240v Push to make/momentary/non latching switch (available everywhere)
-lots of wire/heatshrink/cable ties etc..
-insulated junction box type enclosure

Total cost £13.18 ($20) and a few hours of soldering etc..

I am not claiming this device will prevent a fire, won't trigger falsely occasionally and I am NOT encouraging unattended printing but if you do have to step away from the printer for a short while it seems better to have a little bit of a safety rather than none whatsoever.

Edited 2 time(s). Last edit at 11/02/2015 04:41AM by DjDemonD.

I could use something like this... I was printing a long print (14hrs) and about halfway through I went in to check and smelt a burning smell... thought it was just the plastic, came in a half hr later and sparks and heavy smoke was poring out of my power supply

I bought the power supply from Amazon, so idk why it was so poorly made, but it was scary....

Many thanks for posting this. Seems like a good idea to me, I've just ordered the parts.

Thanks for the post. What do you guys think of buying this product just in case...
Stovetop Fire stop Automatic Fire Extinguishers
[www.stfs-plus.com]

That actually looks pretty good. It looks like there would be a fairly small range of ideal mounting heights, so installation might be a problem, but if you could sort that out it might provide the peace of mind needed to risk an unattended print. Used in conjunction with Demon's electronic shut-off so that you had layered protection it could be just the job.

Seems like a worthwhile addition and its definitely worth testing, but I agree with James it might be difficult to get it high enough to trigger and then drop its fire retardant onto the fire especially if it is at the hot end which might physically be in many positions. Would work over the electronics assuming they are not enclosed.

Just a quick update to this I have been using one each of these units on both of my printers for 3 months now. One enclosed and one open. I have had not one single false trigger in that time (with sensitivity set to just above the maximum setting - I have been informed not to use the extreme maximum setting as it gave one reviewer of this detector problems), but (thankfully) no genuine triggers yet either. It does seem as though it will work much more quickly in an enclosed printer (I have built the enclosure since making these units), so this another good reason to enclose your printer.

Edited 1 time(s). Last edit at 01/21/2016 10:38AM by DjDemonD.

Quote
DjDemonD
Just a quick update to this I have been using one each of these units on both of my printers for 3 months now. One enclosed and one open. I have had not one single false trigger in that time (with sensitivity set to just above the maximum setting - I have been informed not to use the extreme maximum setting as it gave one reviewer of this detector problems), but (thankfully) no genuine triggers yet either. It does seem as though it will work much more quickly in an enclosed printer (I have built the enclosure since making these units), so this another good reason to enclose your printer.

Really? I will try.

Thanks for posting this, I've just ordered the parts and will let you know when I install them.

Seems like quite a worthwhile addition.