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Carbon monoxide poisoning from 3D laser printer may have killed Berkeley couple

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Re: Carbon monoxide poisoning from 3D laser printer may have killed Berkeley couple

#41

Post by dnautics »

stcredzero wrote: post #18

CO poisoning is cumulative. It takes a long time for CO to get unstuck from hemoglobin. (About 2 weeks, IIRC.) It could have snuck up on them slowly, then one evening with the cats "napping" they felt particularly tired and thought to themselves, "We must be in hibernation mode from the chilly weather," then they went to sleep then never woke up. CO is odorless. You might get a headache, or you might only feel tired.…

I think CO doesn't get unstuck from hemoglobin at all. 2 weeks sounds about right, in that that would be the body's mean replacement time for a hemoglobin molecule.

Re: Carbon monoxide poisoning from 3D laser printer may have killed Berkeley couple

#42

Post by lappa »

zokier wrote: post #21
chris_st wrote: post #11

Earlier quoted context omitted.

From Glowforge's website, for their base model: > It needs ventilation via the provided 4″ diameter (10.2cm) hose. We recommend putting the hose out a window.

They also say: > Lasers normally require some ventilation via a small tube out a nearby window. Our optional Air Filter that sits under Glowforge and ventilates using HEPA filters and charcoal, meaning no outside ventilation is required. Best to my knowledge HEPA and charcoal don't help against CO. So running one with the filter in an unventilated space might still be hazardous.

"To qualify as HEPA by US government standards, an air filter must remove (from the air that passes through) 99.97% of particles that have a size of 0.3 µm."

Carbon monoxide is a few orders of magnitude too small to be caught by a HEPA filter, in fact a filter that could filter CO would filter oxygen and nitrogen as well. Such a filter would just be a pump.

There, however, exists a patent for a filter for CO, it works by converting the CO to CO2: https://www.google.com/patents/US5564065

Re: Carbon monoxide poisoning from 3D laser printer may have killed Berkeley couple

#43

Post by iscrewyou »

pmiller2 wrote: post #31
iscrewyou wrote: post #28

I lit a candle last night with a closed window and door. Then it hit me that there is no way there is no CO in this room. Immediately opened my window. After hearing this story, I am never sleeping with my window closed.

With one candle, you're in far more danger from it tipping over than from CO.

Yeah, I don't leave the room without the flame completely out.

Re: Carbon monoxide poisoning from 3D laser printer may have killed Berkeley couple

#44

Post by Animats »

"3D laser printer" probably means a Glowforge. Nobody else calls them that. Their documentation says "Lasers normally require some ventilation via a small tube out a nearby window. Our optional Air Filter that sits under Glowforge and ventilates using HEPA filters and charcoal, meaning no outside ventilation is required." That won't do much if you cut something that emits carbon monoxide when heated. That includes some common plastics, styrene being one.

There are lots of things you don't want to cut on a laser cutter unless you're cutting under an inert gas, or at least nitrogen. Polycarbonate, any of the chlorinated plastics (PVC, some synthetic leather), styrenes, and polyethylene, for example. ABS melts, and Fiberglas's glass component won't cut. Acrylics cut very well. Delrin cuts OK. Wood and cloth are OK. Techshop is careful to teach people about this.

TechShop's laser cutters have compressed air coming in, a big exhaust hose going out, and a fire extinguisher nearby. TechShop has an ad slogan, "Don't try this at home. Do it at TechShop". There's something to be said for that when you're using industrial-strength tools.

In addition to the two people, their two cats died. Operating these things in a closed room is a really bad idea.

Re: Carbon monoxide poisoning from 3D laser printer may have killed Berkeley couple

#45

Post by dekhn »

xiphmont wrote: post #20
dekhn wrote: post #6

Earlier quoted context omitted.

I don't know anything specific in this case (I have been following it since it was first reported, since it's local, and mysterious). But my first suspicion would be the CO2 gas supply to the laser. Low-quality CO2 gas has CO impurities. I think a leak in the gas supply, combined with really poor ventilation, could possibly lead to this situation, but I'm still surprised there would be enough CO to fatally poison 2 p…

The CO2 laser tubes sold to hobbyists are sealed. There is no gas supply. Large industrial lasers use a gas supply in order to cut faster and at higher power. Some home-built tubes do use a gas supply, but virtually no one builds their own CO2 tube to use in a laser cutter when better tubes are available on eBay for $100.

I never said anything about the laser tube. I think it's more likely they did use a gas supply and that leaked.

Re: Carbon monoxide poisoning from 3D laser printer may have killed Berkeley couple

#46

Post by UnoriginalGuy »

pmoriarty wrote: post #25
stcredzero wrote: post #18

CO poisoning is cumulative. It takes a long time for CO to get unstuck from hemoglobin. (About 2 weeks, IIRC.) It could have snuck up on them slowly, then one evening with the cats "napping" they felt particularly tired and thought to themselves, "We must be in hibernation mode from the chilly weather," then they went to sleep then never woke up. CO is odorless. You might get a headache, or you might only feel tired.…

What CO detectors would you recommend?

The consumer ones work fine. They've come a LONG way in recent years.

They may not be accurate but they don't need to be at the levels where CO becomes fatal. It is better to have several inexpensive ones than just one or two $300 highly accurate ones. Since you don't know where the CO will be localised.

You can test them yourself fairly inexpensively look for "HOME SAFEGUARD HO-CO2 Carbon Monoxide Detector Tester, Aerosol." Get a Ziploc bag or similar air tight baggy. Place the alarm in a bag, spray the Aerosol in it, and wait. It should go off in 2-5 minutes. Obviously it is best to do this test outside.

Consumer Reports also tests them:

http://www.consumerreports.org/products/carbon-monoxide-alar...

Re: Carbon monoxide poisoning from 3D laser printer may have killed Berkeley couple

#47

Post by detaro »

dekhn wrote: post #45
xiphmont wrote: post #20

Earlier quoted context omitted.

The CO2 laser tubes sold to hobbyists are sealed. There is no gas supply. Large industrial lasers use a gas supply in order to cut faster and at higher power. Some home-built tubes do use a gas supply, but virtually no one builds their own CO2 tube to use in a laser cutter when better tubes are available on eBay for $100.

I never said anything about the laser tube. I think it's more likely they did use a gas supply and that leaked.

What would you use a CO2 supply for with a laser cutter or 3D printer then? I can't think of anything.

Re: Carbon monoxide poisoning from 3D laser printer may have killed Berkeley couple

#48

Post by pmoriarty »

semi-extrinsic wrote: post #35
pmoriarty wrote: post #25

Earlier quoted context omitted.

What CO detectors would you recommend?

Omega is one company I would trust for this myself; they sell for industrial applications, not homes, and have a good reputation when it comes to sensors. A CO monitor will set you back $235. http://www.omega.com/pptst/AQM-103.html

Is there any way to know that an expensive CO detector like this is worth getting for home use, instead of one costing 10x less?

Re: Carbon monoxide poisoning from 3D laser printer may have killed Berkeley couple

#49

Post by xiphmont »

dekhn wrote: post #45
xiphmont wrote: post #20

Earlier quoted context omitted.

The CO2 laser tubes sold to hobbyists are sealed. There is no gas supply. Large industrial lasers use a gas supply in order to cut faster and at higher power. Some home-built tubes do use a gas supply, but virtually no one builds their own CO2 tube to use in a laser cutter when better tubes are available on eBay for $100.

I never said anything about the laser tube. I think it's more likely they did use a gas supply and that leaked.

I've never seen or heard of a non-industrial laser cutter with a gas supply.

Air assist, yes (to clear smoke and particles from the beam and protect the focus lens from soot), but that's just an air pump, not a gas supply.

Re: Carbon monoxide poisoning from 3D laser printer may have killed Berkeley couple

#50

Post by 172811811 »

stcredzero wrote: post #30
pmoriarty wrote: post #25

Earlier quoted context omitted.

What CO detectors would you recommend?

At his point, I would just pony up some cash. Maybe bug a chemistry geek YouTuber.

I've researched this some months ago, but it isn't a one time cost. I arrived at this model:

https://www.draeger.com/en_aunz/Applications/Products/Mobile...

But if you want to do it right, you also need a calibration station and calibration gas bottles. It is quite an effort.

[No product placement, also look for Honeywell and others.]

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