Was looking for info on how to use textile (or other natural material ) as a air filter. Ok it depends on how dense its woven,but nothing good found. As for a filter test i think it could be something as a frame with a 10 SF of the material and 2 inch water,the flow would be a measure for the pore size.The practical best pore size(s) for volcanic dust. pre and fine filter. maybe even useful as a pollen filter.
There are 2 kinds of filters. Surface filters and depth filters. All your air filters are surface filters. What I would propose is stacking the. A cheap outer filter you can see through to catch the big stuff, a medium mid filter then a super fine stop everything filter. Even a shop vac with dust collection kit would work. I figure if it can stop pollen it will stop volcanic dust. What's the plan to move air through the filter?
The old trick of pantyhose as a pre filter is still a good way to go, followed by a home havc filter element. Another good one is a foam rubber as a pre filter, and you can even use a little spray grease to trap particals. Lastly is a water/fluid element filter, Sort of like the old oil bath filters from engines, these will trap every thing! I still use the old school Oil Bath filters on both my fire trucks because they are easy to clean and service and they trap every thing including soot from smoke.
Just remember that cfm will decrease by the square root of the static pressure. A store bought pleated filter will trap volcanic dust. HVAC dealers also have 5" pleated filters (20x25x5) that are rated to 2000 cfm. There have been tests done with textile filters, and some wools were found to be a good filter, but all load up quickly. Many particle separation filters (think whole shop vacuum systems for woodworking) use a cotton cloth "bag" filter but employ vortex airflow to shed the material into a collector and are not suitable for really fine dust. The ultimate is the HEPA filter, but these are usually employed in large banks to gain surface area as they have a tremendous pressure drop. Filtration is measured in micron particle size with 100 micron being a great filter, 10 micron is a HEPA, and 500 to 1000 a decent home pleated filter. These numbers vary by manufacturer and testing method.
If we are talking in the home, forced air heating, a great trick is to tack 3-4 layers of cheese cloth on the bottom of the air return vents! This is especially useful if you have pets!
Was intending to use e motors to suck the air in, biggest for cooking time smaller one for normal and a small one for the night. Oilbath mm afraid that is for in home use not good, for the oil particles that get in the air,and no idea how efective a oil seperator is And no idea how much particles get in the air at a eruption ,and Manny gasses , no doubt i need a sulfur filter to.
Any filtering system needs to be easily survivable and reusable if necessary depending on the duration of the event ,proximity and wind ,likely years in some cases. In the event volcanic activity demanded air filtration ,the best bet is a water bath ,like oil bath but not hazardous to the environment and easier to deal with. I would convert my swamp cooler blower to draw from a water bath, out side air had to pass through and provide a means of periodically cleaning out the bath as it fills with debris. and having a float valve maintaining the water level. If it is over cast ,which is normally is after an eruption there will be no solar but there might be wind , so a wind mill might be your best source of lighting energy for a long time. A battery system shines here, because a generator need not run 24/7. only enough to top off the battery bank. That too (generator) needs to run and cool with clean air ,so some piping (dryer ducting) from the interior of the home to the generator shed moving the air with a small 12 volt dc computer fan ,only while the generator is running will be sufficient . Food shortages will be serious, we all know about that. Another issue is dealing with the ash building up on the roves , if it get's heavy enough It can collapse a house, especially I it get's wet from rain and or snow . remember it is not snow, it doesn't melt. Shoveling it off and keeping paths clear will be more important than snow removal by comparison. On the water used in the filter system . If a bed the wet ash is laid to drain and settle , that water can be reused in the filter system . A wise man might find a way to make use of the volcanic ash and build something.
@arleigh good idea to use water Yes good point, the weight of the ash specially if wet. The long winter, as in 1816 the year without summer,some say that if its a big eruption ,it could trigger a ice age.time to think underground farming. For the use of the ash look for " roman concrete" the use the ash and we can`t say that its bad, buildings standing for 2000 year
Sulfur dioxide and hydrogen sulfide your 2 main volcanic sulfur gases are both water soluble. The large particle filters that you can see through could likely be blown off with compressed air an reused.
Unfortunately there isn't an easy way to do better than purpose built air filters. Stock up, figure out how to make them last and reuse the larger particle filters.
What are you using for compressed air ? Just being smart . I have several gas engine driven air compressors , and like generators need to be run in a clean environment. If ash accumulates on the filters or in the cooling fins the engine over heats and eventually burns up the engine. Even a brushless generator needs cooling. but most generators are not brushless , so for them it is all the more important to stay clean and dry. (Oxidation on the commutator is why some generators fail) Ideally a steel shed with plenty of room to work and have both units at the ready . Fuel should be in a separate shed with shut off valves out side. If air is piped from the house to the shed via fan or blower while it running, it will make best use of the energy spent. This is providing the house has a filter system dependent on the generator to function.
