Vapor Particulate Filtration (aspergillus)

[diogodasilva]

Hi guys, I was just reading a paper on inhaled cannabis and concerns for the immunodeficient host.
http://www.mascc.org/assets/Pain_Center/2015_March/march2015-11.pdf

I have been thinking about this myself as my wife is undergoing cancer treatment (lymphoma) and here in Brazil marijuana is illegal so there is not a medicinal sterile product available and the risk of aspergillosis is certainly a concern.

Has anyone considered PVDF or Silver membrane filtration (0.2um) on the vapor path to catch the spores ?

Silver Metal Filter Membranes are inorganic, hydrophilic, and made from 99.97% pure metallic silver crystals, making them ideal for corrosive fluid and/or high temperature filtration applications. Great for steam, or air sterilization.
They can withstand heat up to 427C so well within range of a volcano vaporizer for example.
http://www.sterlitech.com/silver-membrane-filters-45348.html
These come in 37mm discs, would have to be cut to fit the Volcano.

PVDF membranes can withstand heat up to 260C and provide high flow rates. They are ideal for venting, sterilizing, and/or clarifying air, gasses.
http://www.sterlitech.com/ptfe-unlaminated-membrane-filter-ptu024750.html
These come in 47mm discs, would have to be cut to fit the Volcano.

The Volcano Easy valve device has a 30mm filter mesh on the upper valve chamber that could easily be adapted with a PTFE/Silver filter to catch the air after the herb.

Aspergillus spores are higher than 1.0um size, so a 0,2 filter would easily catch those.

I am not considering this to vaporize molden weed, the problem is aspergillus can be present even without visible mold and can present a serious hazard for chemotherapy patients due to their immunosuppressed organism

Considering I do not have access to hospital / lab sterilization equipment to sterilize the weed itself, specially for the purpose of sterilizing this type of material, would these kind 0.2um membrane filters be efficient in terms of sterilizing the vapor itself for safe inhalation?

 

[diogodasilva]

On my research, in theory, it seems feasible.
Both membranes seems adequate for the purpose, with slight advantage for the silver membrane given its inorganic nature and also silver being bacteriostatic as an added bonus.

However questions remain to be answered:
- Does it react in a harmful way with the vapor?
- Does it catch the spores?
- Enough flow is guaranteed not to interfere with the device operation?
- Will the filter clog eventually?
- Does it let spores through after some time?
- How often needs to replace?

and so on.

Initial acquisition is quite high as most suppliers only sell in packages not singles,
although it is possible to order lower quantity in sample packages.

Another important question emerges:

Assuming it does catch the spores, would the membrane become a breeding ground for the mold and turn it into a "petri dish" culture media probably increasing the hazard over time?

 

[Seamaiden]

This is new information to me, but reading through quickly, it seems that it would be a good investment for someone with immunodeficiency issues.

 

[diogodasilva]

I did some quick maths and I found a potential issue.
These kind of membranes are pretty airflow restricted.
the 0.2 membrane has an airflow rate of 350 mL/min/cm2 (considering a 10psi pressure)
our working area would be a 30mm disc so A=πr2=π·1.52≈7.06858
a 7.06cm2 area of filtration.
So our little membrane would be capable of flowing 2.471 mL/min/cm2 (considering a 10psi pressure)
Now lets convert this to CFM: 0.087.

So our membrane will only let it flow 0.087 cfm's when pushed with a 10psi pressure.

I have no idea how much CFM's and pressure potential the Volcano air pump has.
But if I had to guess: the CFM is much higher than and PSI much lower.

So this filter would essentially block the air path since probably the air pump on the device does not have enough force to push through the resistance.

I haven't always been the greatest at physics, could anyone help?
Thanks!!

 

[diogodasilva]

Maybe will have to look into custom miniaturized HEPA filters instead of single sheet membranes.

 

[diogodasilva]

Some more maths.
Trying to estimate the volcano CFM rating.
Considering it takes 30s to fill up a 60cm balloon.
The balloon is basically a cylinder with a diameter of 19cm and lenght of 60cm
volume = Pi * radius2 * length
That is 17011cm³= 0.600 ft³

If it takes 30 seconds to fill that, we can estimate the volcano has an air flow rate of 1,2 cfm
CF/CFM = (value) minutes

But how much pressure (PSI) can it hold?

 

[Tardbuster]

Human mouth is too low of pressure. The forced air vape is even weaker.

This issue is corporate mjs magic bullet against home growing. Curious about mechanical traps. Magnet filters, vortex seperation chambers. Who knows what state the spores are in. Encapsulated? Free-floating? Either way, fluid dynamics is out of the vape markets grasp of understanding. Sadly we are on our own when it comes to understanding airflow into our lungs.