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Is 3D Printing Safe? or DIY Testing for HCN from ABS and Nylon 3D Print Material

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Picture of Is 3D Printing Safe? or  DIY Testing for HCN from ABS and Nylon 3D Print Material
  By 3D Printing, we are referring to the majority of FDM or filament feed, BukoBot, Printrbot, Makerbot, TOM and others that use plastic line and a heater block to print parts.
   And, what exactly is "safe" anyway..?
If we eliminate the obvious, the fact that the belts and motors can pinch a finger as well as a heater block operating at 200+c will definitely burn you, we are left with the one unknown.  That is of any hazardous fumes and odors that may be emitted by heating the plastics.  We not only can't see these gasses, but most of us don't have a device at hand to make a measurement.  
  
    The intent of this DIY is to explain how to build a test apparatus to determine the safety of the material you are using to print your parts.  Of course in doing so, we were able to measure and report on various common matereials.

    If you just want an answer to the question "Is 3D Printing Safe" without reading the excruciating details, you're in luck.

"Yes" Based on our measurements using the world Safety Authorities (OSHA NIOSH ACGIH) Limits, 3D Printing is safe.
There was NO measured HCN from "3D Printing ABS" based materials at specified temperatures.
There was NO measured HCN from "3D Printing Nylon" based material at specified temperatures.
There was 0.1ppm of HCN while printing with a "Non-3D Printing" material (Trimmer Line)

Even in our worst case testing in an enclosed 12" cube at 420C (788F) for 10 min the maximum reading was 1ppm, again, trimmer line.  The OSHA safe limit is 4.7ppm.

Quick Q and A

    Did you find any items of note?
  1. We found that before the threshold was reached, the plastics became "unprintable" and would halt/jam the printer.
  2. There is a lot of naturally occurring HCN.  You will probably encounter more HCN at an outdoor marshmallow campfire than we measured in our testing.  Due to it's shear quantity as opposed to the small quantity we print, burning wood creates a lot of HCN.  
  3. Again, our testing shows no HCN measured from 3D Printing materials at correct temperatures.

     What gas would make 3D Printing unsafe?
An excessive amount of Hydrogen Cyanide (HCN) - A gas emitted by plastics when they are set on fire or breach pyrolysis.

     And what is an excessive amount of HCN?
The international (OSHA NIOSH ACGIH) maximum allowable exposure to HCN is 4.7ppm

    So? How much HCN did you measure while actually printing?
3D Printing  ABS from various 3D  Printing material suppliers in China, the EU and US = None
3D Printing Nylon from taulman3D 3D  Printing material supplier in the US = None
Two brands of Trimmer or weed-whacker Line mfg in the US = .1ppm

     Where did you get the 3D Printing material?
Defined 3D Printing Material -
ABS1 = China - A
ABS2 = China - B
ABS3 = EU
ABS4 = US
Nylon1 = US
Nylon2 = US

Non 3D Printing Material -
Trimmer1 = US
Trimmer2 = US

      What did you use to measure the HCN?
Industrial Scientific Corporation T-82 Single Gas Monitor
Calibrated HCN Sensor
Certified calibration 1 day before testing
Certificate of calibration
Certified by UL, CSA, CE
Resolution .1ppm

    What was your absolute highest reading?
Trimmer line "A" at 220c+ = 0.6ppm -1.0ppm in a semi-sealed enclosure (12" x 12" x 24") for 10 min
This is a "cumulative test" as the gas is allowed to accumulate in the enclosure, thus it's concentration in ppm is higher.
This is NOT a printing test, but one of several tests done to answer cumulative concentration questions.

Excruciating details,

"Safe"...?

Electrical:
     Today, most 3D Printers use modular power supplies.  Either re-purposed ATX (Computer PS) or enclosed wall power units, such as used by laptop computers.  These are already UL listed and tested.  Most of these power supplies don't exceed 24 volts, including power to the Hot-End.

Mechanical:
     Again, there are obvious safety concerns with respect to motors and belts, pulleys and or threaded rods.  However, once we see these components in operation, we know to use a bit of caution and not stick our fingers in the moving parts.

Thermal:
      There are a few hot components we need to be aware of.

  1. Stepper motors - These can get hot, but usually not hot enough to burn you.  Most motors have an attached fan to keep them cool so as to last longer as heat damages the motors bearing surface over time.    
  2. Power supply - These are covered units, but as they dissipate heat we need to make sure they have access to ventilation, i.e. don't block the little cooling holes and replace air filters when needed.
  3. Build table - These are the platform we actually print onto.  They are usually heated to a temperature that will burn you.  Almost all of these are vividly marked in some manner warning of "HOT" and "Do Not Touch".  This is an actual UL requirement if the printer is certified.
  4. Hot-End or Heater block - This is the component where the plastic is melted and flows from a small opening/nozzle. This will be very hot.  Between 180C (356F) and 275C (527F).  Again, this will not just burn you, but mark you for life.  Recently, you may have noticed that some 3D Printers have started to ship with brackets, or shields around the Hot-Ends.  And in some cases, a completely enclosed printer where access is only through a door or lid.  This comes from various UL and CSA requirements for finished goods where rules to protect the consumer come in to play.  As of yet, 3D Printer kits have not been required to meet a lot of the same rules. 
Chemical/Gasses:
    While most of us have tape measures and wrenches to make mechanical measurements/adjustments, volt meters to make electrical readings and temperature sensors to measure hot parts, almost none of us have unique gas detection equipment to detect gasses emitted by printing.  And because we are changing the state (heating and melting) of plastics, they will emit  fumes and odors.
   
3D Printing Measurement History
      We can't say that no one has made this specific measurement prior to now, just that we were not able to find any information on-line or through contacts.
 
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txdawood1 year ago
Thank you for this information-full instructable! Good job!
taulman (author)  txdawood1 year ago
txdawood, Thanks for your comments.
eecharlie1 year ago
Is HCN the only dangerous off-gas that can be produced by heating ABS and Nylon in the temperature range used by 3D printing?
taulman (author)  eecharlie1 year ago
charlie, HCN and Carbon monoxide were tested due to their toxicity.
For a full list of gasses, download the linked Barnes report for Nylon and the following link for ABS.
fire.nist.gov/bfrlpubs/fire86/PDF/f86017.pdf
Again, most gas emissions begin at much higher temperatures than we use for 3D Printing.
However, as we say in all of our able's, one should "vent all fumes and odors"
eng_Andy1 year ago
Testing for HCN and CO combustion products in melting plastic? Shouldn't you be testing levels of things we know are far more likely to escape, such as Butadiene or Styrene from ABS?

Staying in a confined room with a 3D printer using some blends of ABS can be enough to make you keel over, so I'd be more concerned about quantifying exposure to those two carcinogens.
taulman (author)  eng_Andy1 year ago
Andy, The focus on HCN was due to it's toxicity. Of course there may be additional gasses depending on the source of the material. We found that even though the results were equal for all ABS tests, during our material "sourcing effort" we had to pay attention to the blog and wiki posting to stay away from known problem vendors. For a complete list of known emissions, download this pdf.
fire.nist.gov/bfrlpubs/fire86/PDF/f86017.pdf
This document will show all emissions of gasses, but you'll also note that most emissions of these gasses begin at temperatures equivalent to fire.
However, as we say in all of our able's, one should "vent all fumes and odors"
Also, because these gasses are carried past the sensor on thermals, you should be able to use the able to measure for other gasses with alternate sensors.
scott51341 year ago
I bet there was not the concern and testing when copiers and laser printers came out. Heating powders at high temps can be just as hazardous, if not more. There have been burns to people who pull the drums out to unjam paper. You would think they would have made timed or thermal locks to insure cool down but that area has been left alone, maybe do to its necessity
Sep 16, 2012. 8:12 AMscott5134 says:

"I bet there was not the concern and testing when copiers and laser printers came out..."

Do you have any proof for that assertion?

Printer toner (and for that matter inkjet inks) have been extensively tested and characterized with regard to chemical content. Inhalation, ingestion, absorption effects to name a few.

You also mentioned hot surfaces. Most laser printers have thermal shields to keep your fingers away from the hot stuff. They also have interlocks to protect you from an errant laser beam.

So, yeah, I'd say your statement is the opposite of true.
ac-dc1 year ago
lol, but is it "safe" to be sitting on your butt reading this message or are there inherent health and environmental issues?

Chicken little please do something productive.
lewisb421 year ago
This is a great idea for an Instructable!
taulman (author)  lewisb421 year ago
Thanks for the comment!
With 3D Printing taking off, we are sure there are others out there looking into additional polymers. While it's not free, the cost of having a plastics company extrude a short run of a new polymer is well worth the effort.
Lorddrake1 year ago
WOW .. great job. tons of really good info. Everything is laid out well and clearly documented.

5 stars.

thanks.
taulman (author)  Lorddrake1 year ago
Thanks for the comment! We hope to update this able in a month or two with the videos we captured. There are about 40 hours of live video of both the real-time testing as well as closeups of the actual degradation of each sample.
Again, thanks
Cambenora1 year ago
Excellent work guys. I think there should be more of this type of informational instructable; it's certainly worthwhile. A+.
taulman (author)  Cambenora1 year ago
Thanks for your comments. We agree, this site is a great place for this type of DIY testing as well as design and build projects!
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