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What is Needed
The supply chain of ventilators should be activated or alternatively hospital air supply can be used to generate a constant inflow.
One Direction Valve
In the event of paroxysmal coughing the use of a one direction valve could prevent the virus from coming back to the source
We have developed a new design based on what reported hereafter. The new design can be downloaded HERE . There are two versions of the mask and therefore there are 2 adapters which need to be printed depending on the version: Left mask: ”small” (model 1); right: “large” (model 2).
The optimized design here above, was done by testing and improving previous designs by ISINNOVA
WARNING: Take proper acttion to prevent dangereous inhalation of plastic residues from 3D printing: clean all loose pieces of plastic and after 3d printing use a heat gun to “burn” plastic hairs away
Detailed post-processing instructions can be found HERE under “Print instructions”.
|Separation inflow (center) outflow (sides)||Design reported HERE without separation of inflow and outflow only to use for protection of health workers|
There are furthermore 2 types of the masks and therefore two possible sizes of the connectors. The one reported by ISINNOVA is for one of the two sizes. On this site you find new designs for both sizes. The choice of material may be important for sterilisation purposes . We advise to use PET-G / CPE considering that it can wisthstand 80 C for longer than 15 minutes which is what needed to neutralise the virus.
|Adapters designed by Vincent Groenhuis of the RAM group of the University of Twente, can be downloaded HERE.|
The last design has a better separation of the inflow and outflow on the backside.
Current design (derived from Italian Charlotte valve):
Ports: Intake port: I.D. 19.4 mm, O.D. 22.0
Exhaust port: I.D. 17.4 mm, OD 19.4 mm (10 mm depth), then OD 22.0 mm
Be Carefull in the connection: the connection which is more toward the side, is the OUTFLOW and should be connected to the filter and PEEP valve. The connection which is more straight is the INFLOW from the CPAP or airsource.
All available designs with links are reported in the following table:
|Small Maks connector, for tube and filter||Big Maks connector, for tube and filter||Small Maks connector, for tube on both sides||Big Maks, connector for tube on both sides|
small_v085.stl more tight mask-adapter
small-d_v0851.stl more tight mask-adapter
The Correct design which separates inflow and outflow is reported here. The outflow should be filtered to prevent contamination of the air. This can be done e.g. with the filter reported in the picture hereafter. These filters are common in the OR and ICU with 22mm female/male connection.
|Correct Connection with separate inflow and outflow||Filter which should be connected at the outflow of the splitter here beside|
To keep a good level of pressure in the mask so that the lungs are properly expanded, there is the need for a pressure regulator, what is called a PEEP after the filter described above. Alternative is to put the pipe literally in an immersed basket of water with a depth of 5-20 cms.
|PEEP valve by Ambu||Alternative via the immersion of tubin in water (5-20 cm deep)|
There are some provisional designs you can print to hold the tubing on the side of the baquet. You find the designs in the following table. It depends on the baquet, but the design on the right seems more stable.