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Bioweapon Defense and HEPA

Discussion in 'Model X' started by ReturnZero, May 6, 2016.

  1. ReturnZero

    ReturnZero Member

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    I'm trying to figure out the relationship between the Bioweapon mode and the HEPA filter. It seems like in order to utilize Bioweapon mode, the fans need to be on full tilt - which makes sense, it needs to create positive pressure inside the cabin. Gets a bit annoying though when you want to use it.

    But what about the HEPA filter? Is that always working, regardless of fan speed or mode? Does it work in recirc, or fresh air mode, or both?
     
  2. Saghost

    Saghost Active Member

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    I haven't seen an authoritative source yet. I believe outside air always goes through the HEPA and actived charcoal in all modes. I'm not sure about recirculation.

    I believe bioweapon mode closes or at least reduces the outlets which allow air out of the cabin, along with boosting the fan speed to develop positive pressure.

    Both Tesla and independent reviews show that the combination cleans the interior air quite quickly after they are engaged.
     
  3. ReturnZero

    ReturnZero Member

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    I haven't either - was hoping someone had more insight but perhaps not. I didn't see it in the user manual but I admit I didn't look that hard...

    I've definitely read the reports about how effective it is and I believe it. Was just looking for a way to get some/most of that benefit without blasting the fan.
     
  4. mspohr

    mspohr Active Member

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    The normal operation of the HEPA filter will clean your air better than most cars. The bioweapon mode is for extreme pollution like Bejing or Harris Ranch.
     
  5. ReturnZero

    ReturnZero Member

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    So is the HEPA filter always operational? Or only in bioweapon mode? And what about recirc vs fresh air mode?

    We've having a high pollution advisory day today in Dallas. Obviously nothing like Beijing, but still made me think of it.
     
  6. bensch

    bensch Member

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    Just wanted to revisit this thread to see if anyone has any input to how the HEPA filter works without the Biodefense mode activated.
     
  7. spottyq

    spottyq Member

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    Bioweapon mode is nothing else than having the car set to fresh air intake (not recirculation) and fan cranked all the way up.

    Well, I don't know that for a fact, but the alternative seems stupid. It would mean that there is a separate path for the air to go without passing through the big HEPA filter, with the mechanics needed to control the airflow. It makes no sense. The air has to pass through that filter whatever setting you have chosen.
     
  8. travwill

    travwill Member

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    There are two air filters in the MX though right, that is what they showed on the unveil. A smaller one, that is still larger than most cars by a little, and the huge HEPA one. Seems like regular mode just passes through the smaller filter...
     
  9. Saghost

    Saghost Active Member

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    Descriptions of the system make reference to an activated carbon filter in addition to the HEPA filter- possibly that's the other filter you're seeing? If so, the air would go through both filters sequentially.
     
  10. Brandon332

    Brandon332 Member

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    The HEPA filter is definitely in use all the time. I've driven 6000+ miles, and have never had any external smell come into the cabin. Have never really used to bioweapon mode, but I've been behind trucks with black smoke, dead skunks etc and no smell at all happens. the AC was on during these times. It just has to always go through the bio mode.
     
  11. spottyq

    spottyq Member

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    Yes they are two air filters, but they are always used sequentially. The HEPA filter is the primary and the smaller is the secondary as per the TMX unveiling video.

    It still makes no sense to have two separate conduits (and all the needed mechanical controls) for air to get into the cabin. It's at best a huge waste of space. And for what ? To have a **worse** air quality (since it would bypass the HEPA filter in normal operating mode) ? It just makes no sense.
     
  12. GuyHall

    GuyHall Member

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    Isn't the Hepa filter able to keep smoke out of the car? We were approaching a forest fires so we turnEd on our bio defense, but we could still smell smoke.
     
  13. 777dgt

    777dgt Member

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    I believe bioweapon mode creates positive pressure inside the cabin and therefore prevents the smallest particles from entering the cabin. This is true of all "clean" rooms.
     
  14. royewest

    royewest Member

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    When I picked up my S they told me using Bioweapon mode would use up the filter faster. (I asked before I realized the noise it makes -- now we use it only when passing through smoke, etc.) I don't know what to make of this advice, frankly: the consensus about air always passing through it makes much more sense.
     
  15. Saghost

    Saghost Active Member

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    That's probably true, too. Bioweapon is drawing more air through the filter faster to create the positive pressure, which presumably means more things caught in the filter per unit time.
     
  16. systemcrashed

    systemcrashed Please Reboot

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    Depending on when you activated BWD mode, your cabin may not have been fully pressurized, thus allowing some smoke to make it inside.
     
  17. Saghost

    Saghost Active Member

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    In theory it should. In practice, lots of details matter - crosswind being foremost among them.

    Bioweapon Defense Mode works by building a small positive pressure inside the cabin, so that in a static environment any leaks will be from the inside to the outside of the car and then by drawing all the inside air through the filter stack.

    However, if there is a wind against the seal area, that also creates a higher pressure region, so enough wind against a leaky seal will cause unfiltered air to push into the cabin from the upwind side.

    How much is enough depends on a bunch of factors - how tight the car is in general (and thus how high the internal pressure is,) how tight the specific seal is (how much pressure differential can it withstand,) how large are the foreign particles (how much does the seal have to deform,) and probably some others that I'm not thinking of right now.

    Bioweapon is a great addition for casual use, but the cars aren't really adequately sealed for dangerous environments, and you shouldn't assume Bioweapon mode will prevent anything dangerous from entering the cabin (it will greatly decrease the amount entering regardless, but it can't always keep everything out.)
     
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