1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Takata Airbag Propellant

Discussion in 'Fred's House of Pancakes' started by bwilson4web, May 22, 2015.

  1. bwilson4web

    bwilson4web BMW i3 and Model 3

    Joined:
    Nov 25, 2005
    27,068
    15,372
    0
    Location:
    Huntsville AL
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    Source: http://www.nytimes.com/2014/11/20/business/takatas-switch-to-cheaper-airbag-propellant-is-at-center-of-crisis.html?_r=0

    The new airbag propellant was supposed to be the next big thing for Takata in 1998. An engineer for the company, Paresh Khandhadia, declared it “the new technological edge” in an interview with a trade magazine then.

    Based on a compound called tetrazole, it was seen as a reliable and effective compound for inflating airbags. Yet despite the fanfare, by 2001 Takata had switched to an alternative formula, ammonium nitrate, and started sending the airbags to automakers, including Honda.

    Ammonium nitrate burns fast but has the ability to detonate. Instead of burning, a shock wave triggers an explosion ... a grenade. This is a problem with many propellants that there can be a fine line between rapid burning as happens in our engines versus detonation that has explosive over-pressures and shock waves.

    I understand some Toyota vehicles were involved but nothing about the Prius, yet.

    Bob Wilson
     
    Mendel Leisk likes this.
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,571
    48,862
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    i knew, way back when, that the air bag mandate would eventually blow up in our face.:cool:
     
  3. wjtracy

    wjtracy Senior Member

    Joined:
    Sep 19, 2006
    11,309
    3,586
    1
    Location:
    Northern VA (NoVA)
    Vehicle:
    Other Hybrid
    Model:
    N/A
    They say ammonium nitrate is a bad choice for airbags due to temp and moisture sensivity.
    Takata was the only user of ammonium nitrate due to the known issues nobody else tried it. Unclear to me if Takata kept using ammonium nitrate but the recalls seem to go back to pre-2008 vehicles.

    Apparently guanidine nitrate is a better choice these days. I never heard of guanidine nitrate but it is commonly known in the rocket motor industry (who gave us airbag technology). Apparently sodum azide was the orginal propellant but it had issues too.
     
  4. ftl

    ftl Explicator

    Joined:
    Jun 2, 2009
    1,812
    790
    0
    Location:
    Long Island NY
    Vehicle:
    2012 Prius c
    Model:
    Three
    Guanidine starts life as bird droppings:
    Guanine - Wikipedia, the free encyclopedia
     
  5. wjtracy

    wjtracy Senior Member

    Joined:
    Sep 19, 2006
    11,309
    3,586
    1
    Location:
    Northern VA (NoVA)
    Vehicle:
    Other Hybrid
    Model:
    N/A
    ftl likes this.
  6. bwilson4web

    bwilson4web BMW i3 and Model 3

    Joined:
    Nov 25, 2005
    27,068
    15,372
    0
    Location:
    Huntsville AL
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    So if you are in an accident, you're in a world of sh*t?

    Bob Wilson

    Late thought to share about ammonium nitrate.

    Ordinary fertilizer, ammonium nitrate is sold in a clay 'pill' that suppresses a detonation shock-wave. But to make it explosive, it is typically mixed with diesel, an incompressible liquid. The 'humidity' aspect assumes a condensing water vapor selectively dissolves the ammonium nitrate to remove it from a matrix of shock-wave inert material. Then it dries leaving a solid piece that can detonate.

    Regardless, there are safer propellants that are less subject to detonation. For example, black powder does not detonate nor does gun cotton. They can explode if confined but it is the vessel failure that makes the explosion, not a detonation effect.

    So why do I know these things? At age 7, I was making my own black powder with chemicals bought at the local drug store for my rocket experiments.

    Bob Wilson
     
  7. wjtracy

    wjtracy Senior Member

    Joined:
    Sep 19, 2006
    11,309
    3,586
    1
    Location:
    Northern VA (NoVA)
    Vehicle:
    Other Hybrid
    Model:
    N/A
    One pyromaniac to another, last year we visited DuPonts old gunpowder factory in Deleware for a tour and demo. 50-years too late, oh what I could have done with that knowledge when I was a kid. They said one of the benefits of potassium nitrate was moisture resistance (non hygroscopic).

    Ammonium nitrate is not only hygroscopic, it changes phase/behavior just due to temperature variations in a car (hot days/cold days etc). So that's why it was not used except by Takata, it was considered too risky in an air bag scenario. I don't know why potassium nitrate is not used, but they need something that's stable over time and does not create toxic fumes on ignition.
     
  8. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,072
    14,976
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Thinking that 14 years of hot days/cold days might not be desirable in that case, for peace of mind I've dug into my Gen 1 and confirmed the driver and passenger airbags were made by Daicel Safety Systems, not Takata. The driver's inflator is a straight pyrotechnic one:
    DEE5000-web.png

    ... while the passenger inflator is a "hybrid" design: it has a canister already containing a highly-compressed gas (behind a rupture disc), and a pyrotechnic charge to make more gas, drive the pressure up, and rupture the disc. (The passenger-side inflator has a much bigger bag to fill.)
    DHD5002.jpg
    Their model numbers and BAM (German Federal Institute for Materials Research and Testing) registration numbers are shown on pages 73 and 81 of this BAM registration list, but I was hoping it would say more about the propellants used, and it doesn't.

    They've filed a ton of propellant patents over the years, but I'm not sure how much peace of mind that gives me, because in the years shortly before the Gen 1 came out, they had at least one patent for a propellant that doesn't use ammonium nitrate, as well as another patent for one that does. :unsure:

    Not sure how to learn more about what propellant they ended up using in these exact inflators....

    -Chap

    Another thing you can do with off-the-shelf, automotive airbag hybrid gas generators: launch torpedoes better.

    I was trying to find something, anything, that would say what the intended shelf life of a hybrid gas generator is supposed to be, and that was the best reference I found. Says it should be "at least twenty years" and the automotive airbag standards "exceed military standards for reliability."

    As one more interesting factoid, it says one typical hybrid gas generator produces "about twenty-five kilojoules".

    -Chap

    Hmm, Daicel's DEE5000 (the steering wheel inflator) seems to have been pretty popular, with 31 auto manufacturer customers in Germany (see pages 250 through 253).

    The DHD5002 hybrid generator for passenger bag had 9 auto manufacturer customers there (pages 59, 60).

    -Chap
     
    bwilson4web likes this.
  9. bwilson4web

    bwilson4web BMW i3 and Model 3

    Joined:
    Nov 25, 2005
    27,068
    15,372
    0
    Location:
    Huntsville AL
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    Chapman takes the prize:
    [​IMG]

    [​IMG]

    Bob Wilson
     
    #9 bwilson4web, May 29, 2015
    Last edited: May 29, 2015
  10. tochatihu

    tochatihu Senior Member

    Joined:
    Apr 10, 2004
    8,972
    3,501
    0
    Location:
    Kunming Yunnan China
    Vehicle:
    2001 Prius
    One pyromaniac to another, I saw students pounding on NH4NO3 with diesel (this is called AFE yes?) with metal hammers on metal top desk to make the bits smaller so they could accurately weigh for a fertilization experiment. In a room containing many 100-kg bags of the stuff. I advised then that there was only a small chance they could detonate it. But if they did, they might all die and blow a big hole in the building.

    Pound on that stuff with wood, and with wood underneath. Yikes.
     
  11. wjtracy

    wjtracy Senior Member

    Joined:
    Sep 19, 2006
    11,309
    3,586
    1
    Location:
    Northern VA (NoVA)
    Vehicle:
    Other Hybrid
    Model:
    N/A
    Yikes! We don't allow chemicals anymore....how a kid becomes a chemist today...I do not know.
     
  12. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,072
    14,976
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    AFE doesn't ring any bells as a term I've run into before. I thought ANFO was the common lingo for when it's been mixed with fuel oil, but I thought that was only when you wanted to blow stuff up. What would diesel be doing there, in a fertilization experiment?

    But then, like many non-pyros, all I've ever learned about ANFO was what Timothy McVeigh and Terry Nichols taught us in 1995. (Reportedly, Nichols was busy giving his lawn a really, really heavy NH4NO3 application, as the law pulled up to chat with him. Shades of Fargo, only real life....)

    -Chap
     
  13. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,571
    48,862
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    tonights news doesn't bode well...
     
  14. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,571
    48,862
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    march 31, 2016: 'texas teen dies when takata airbag explodes in honda civic after collision.' dang, i gotta get my dakota in for recall.
     
  15. SAronian

    SAronian Active Member

    Joined:
    Mar 18, 2013
    334
    144
    0
    Location:
    Oakland, CA
    Vehicle:
    Other Electric Vehicle
    Model:
    N/A
    Took our Honda Fit to the dealer this week for the Takata recall and found out they won't have replacement inflators for 90 days. To their credit Honda is paying for rentals and storing the Fit until repaired.
     
    bisco likes this.
  16. wjtracy

    wjtracy Senior Member

    Joined:
    Sep 19, 2006
    11,309
    3,586
    1
    Location:
    Northern VA (NoVA)
    Vehicle:
    Other Hybrid
    Model:
    N/A
  17. Coast Cruiser

    Coast Cruiser Senior Member

    Joined:
    Mar 12, 2016
    2,267
    2,571
    0
    Location:
    Pacific Coast Highway
    Vehicle:
    2016 Prius
    Model:
    Three
    Is Toyota still installing Takata airbags in new vehicles coming down the assembly line? Do you trust Takata going forward? Hell NO! How come another company hasn't stepped up to manufacture a better product? Put Takata out of business!

    It will be several years before various auto dealers get done replacing 13 million defective airbags.

    There was a story awhile back, that even the replacement airbags were found to be defective in a certain brand of car. Crooked bastards.

    The young girl in the Honda Civic that died, was only going 15 mph.
     
  18. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,571
    48,862
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    it will be interesting to find out if chrysler has the parts yet, or would give me a rental. the recall still says they are prioritizing humid area's.
     
  19. wjtracy

    wjtracy Senior Member

    Joined:
    Sep 19, 2006
    11,309
    3,586
    1
    Location:
    Northern VA (NoVA)
    Vehicle:
    Other Hybrid
    Model:
    N/A
    do not know I would assume there is no more use of ammonium nitrate which was the problem. Prius has not had the issue.

    Interesting to recall many decades ago the auto companies were fighting airbags citing in part issues like this and cost. But I guess the lives saved outweighs the sad problems. Also average cost of cars since those early fights has probably gone from $3000 to $35000 average, so people in the end did pay more for cars (I assume after inflation).
     
    #19 wjtracy, Apr 8, 2016
    Last edited: Apr 8, 2016
  20. Former Member 68813

    Former Member 68813 Senior Member

    Joined:
    Oct 3, 2010
    3,524
    981
    8
    Location:
    US
    Vehicle:
    Other Hybrid
    Model:
    N/A
    Ammonium nitrate? OMG, what were they thinking?

    Texas city disaster tough us it can explode in adverse conditions.

    [​IMG]
     
    #20 Former Member 68813, Apr 8, 2016
    Last edited: Apr 8, 2016