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The word "How?" springs to mind at this point.
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For those foolish enough to throw objects at police (there are far more effective and less dangerous ways to undermine authority) some protective clothing is useful.
Motorcycle helmets provide protection against impacts, and give an element of anonymity, but don't exclude irritant gases.
have developed an add-on filter system which seals round the neck of the wearer and the lower aperture of a full-face helmet, converting it into an effective gas mask while permiting relatively free head movement.
The system comes with a strip of self-adhesive closed-cell foam to seal around the visor.
In areas with high levels of pollution from vehicles, the system protects riders from the majority of particulates and gases.
Placard Printing Van
Vending concept [8th of 7, Jan 23 2020]
[bs0u0155, Jan 23 2020]
Helmet Air Pump
[bs0u0155, Jan 23 2020]
||I was gonna say I was surprised there were no filtered
helmets, then a quick google showed a bunch <link>.
||I don't think the idea as posted would work. You are
relying on the tidal nature of the wearer breathing. Any
restriction would prevent some exchange and instead, the
wearer would be breathing mostly the dead volume inside
the helmet and padding, actual fresh air exchange would
be small. You might improve things with some valving,
but you still need a seal against the neck, good against
positive and negative pressure. That would feel horrible
and would need careful fitting.
||The linked solutions of constant positive pressure supply
is a much simpler and more effective solution. I'm
surprised noone has added a temperature controller and a
Peltier to give cooled/warmed air. One of the worst
aspects of motorcycle helmets is overheating, fan, tube,
12V supply - all the ingredients are already there.
||There are similar devices, but none specifically engineered to protect both vision and respiration. Oral/nasal filters are Baked and WKTE. Some power assisted dust and welding masks come close but don't provide impact protection.
||The neck seal and low-restriction filters and valves are available off the shelf. The increased dead volume over a conventional respirator isn't an insurmountable problem, though visor fogging might need active mitigation.
||The self-sealing foam will need to be very low modulus.
There are some blood vessels in the neck that can be affected
by surprisingly light pressure.
||//visor fogging might need active mitigation//
||It's not a major problem. On Good helmets there's already
a partial seal/shield running along the top lip, It's meant
to leave your nose clear in case any accident-induced
liquids come out of the mouth. In addition, there are
often tiny vents in the forehead region that actively force
net movement of air down. Obviously they'd have to go.
||//The self-sealing foam will need to be very low
||Mate of mine works in PPE testing. The only way to go is a
full rubber head balaclava thing sealed at the chest, like
a dry-suit, or a very thin rubber inflatible donut
||What you do in your own time is your affair, [bs].