We will describe the general design principle of the latest version of the mask in this secion. The is also a similar [_section on the older version_](#4-older-version), that is more sucint as it is not the recommanded version _at least not without you tweaking and understanding this version_.
To know how to assemble/print this mask, see the [_section on mask assembly_](#2-mask-assembly), and if you want to change parameters check the [_section explaining parameters_](#3-explanation-of-parameters).
### Maintenance
It is recommanded to apply grease (_prefere food safe vaseline_) arround thread, arround the insuflation mask connector and arround the perimeter of the one way valve to improve the seal.
If you are using a 3D printed (_or DIY_) filter (_as described in [the section bellow](#1-b-filtering-cartidge)_), change regularly the filtering material - in general activated charcoal - and clean the enclosure if youdon't change it.
In general do a fitment check before using the mask : put a piece of plastic (_or your hand_) at the entrance of the filter you are using, and breath in hard. You shouldn't fill air entering you lungs, and the mask should compress to you face under the suction force.
The final design relies on an insuflation mask (_with a standard 22m inner diameter connector) for good fittment to the face of the user. The advantage of this is that the fittment is good, there are mumtiple sizes to choose from, and insuflation mask are readly available (_they are suppose to be single use only, and are used at every anesthesia, CPR and in many other cases_) and **cheap** (_There are some available for arround 2€ at [medisafe.fr](https://www.medisafe.fr/secours/oxygene/insufflateur-bavu/masque-insufflateur-usage-unique.html#MA285-2612-TAI1140_) for example_).
The downside of this method are that firstly these mask tend to deteriorate over time and with use as they are ment to be single use item, however they are obviously swapable so they can be switched when unsusable ; and secondly that the height of these mask and the length of the adapter puts the majority of the mask weight far from the face and thus a bit unconfortable, espacially under quick head movments.
This mask supports standard 40mm threaded cartridges - sometimes also known as "_nato threaded_" cartridges - which the standard dimensions are defined in [sources/dimension/nato_thread_spec.png](./sources/dimension/nato_thread_spec.png).
We also provide a 3D printed cartridge following this standard and compatible with this mask and other standard gaz mask in the [3D-printed-parametric-respiratory-one-way-valve](https://git.deuxfleurs.fr/distorsion/3D-printed-parametric-40mm-gaz-mask-canister) repository, which is a submodule of this repository located at [./3D-printed-parametric-respiratory-one-way-valve](./).
:warning: **WARNING : _Please don't use a 3D printed cartridge (or even our mask) in life threatening situations !_** :warning: Or at least understand the inner working of gaz mask and test your gaz mask (_especialy its fittment to your face_) before using it.
This maks uses a (_one or two_) 3D printed one-way valve : one for exhaling, and can also use one for inhaling. The design of the one way valve is presented in more detail in the [3D-printed-parametric-respiratory-one-way-valve](https://git.deuxfleurs.fr/distorsion/3D-printed-parametric-respiratory-one-way-valve) repository, which is also a submodule of this repository present at [./sources/3D-printed-parametric-respiratory-one-way-valve](./sources/).
The "ouput" one way valve (_which is used for exhaling_) is usefull to make breathing easier by not forcing you to exhale through the cartridge, while preventing air to come in without passing through the canister. A filter can be held in front of this valve to prevent particles from deposing at the exit of this valve, which could reduce its seal while inhaling. However, this valve is an output valve and will thus naturally push away suspended particles, and it is oriented down thus making gravity help in preveting particles from sticking to the valve. Thus to make the mask lighter it is not recommanded to use the longer version of the output valve that is made to hold a filter.
An "input" one way valve (_used for inhaling_) can be used to force air to not exit through the cartridge. This makes both exhaling and inhaling harder, and this thus not recomanded, _at least without tweaking other parameters_.
The older version of the mask can be made either to work with standard 40mm cartrdige (as the newer version), or an integrated cartridge which makes it more confortable to use.
As this version is not the main supported version, we will not go into detail into explanation, and we will foccus on differences with the latest version.
### 4.a - _Older version :_ Interfacing with the face
_Coming soon !_
### 4.b - _Older version :_ Filtering cartidge
_Coming soon !_
### 4.c - _Older version :_ One way valve
_Coming soon !_
### 4.d - _Older version :_ Short explanation of parameters
