warning: boring technical details
The hills are on fire again, but we don't have a pressurizer to contaminate this time. It's still in parts in the back yard, except for the blower, which is on the kitchen floor next to a mostly assembled dryer. You could say we have a bad habit of taking everything apart, but we have very clean things once we put them back together. The thing is that now we're thinking about making our own really good house pressurizer, so here's what I learned today:
Air cleaner blowers typically have a scoop around the impeller (here's an example) so the air doesn't go past the motor itself. I hear you have to be careful to pick one that only takes air from the side away from the motor, and you want an impeller bigger than about 8 inches in diameter to reduce the noise. For airflow, you want something above 400 CFM (cubic feet per minute) because you end up slowing that down when you start sucking or blowing the air through a bunch of filters.
Standard furnace filters come with a MERV rating, and I already forgot what that stands for, but it tells you how good your filter is at filtering out very small particles. The more efficient your filter is, the higher its resistance (pdf), which is what slows down your blower. Filters have an initial resistance, which is the resistance of a clean filter in terms of how high it can suck a column of water given a particular face velocity (air speed approaching the filter). When the filter is dirty, its efficiency is great because not much can get through it, and that's when you get your final resistance. And filter resistance matters in terms of how much electricity it takes to turn your fan, so here's a page with a handy chart (pdf) of how much various resistance filters cost per day.
If you'd like to increase the amount of air you can get through your filter, you could double the area, which doubles the CFM (see page 4 here, pdf). You can't change the resistance, however, without buying a different kind of filter.
And here's how you get to the Arizona wildfire page, which I find fascinating and totally inadequate, but much better than what you'd find in the newspaper, considering the newspaper hasn't apparently even heard of this fire yet.
Air cleaner blowers typically have a scoop around the impeller (here's an example) so the air doesn't go past the motor itself. I hear you have to be careful to pick one that only takes air from the side away from the motor, and you want an impeller bigger than about 8 inches in diameter to reduce the noise. For airflow, you want something above 400 CFM (cubic feet per minute) because you end up slowing that down when you start sucking or blowing the air through a bunch of filters.
Standard furnace filters come with a MERV rating, and I already forgot what that stands for, but it tells you how good your filter is at filtering out very small particles. The more efficient your filter is, the higher its resistance (pdf), which is what slows down your blower. Filters have an initial resistance, which is the resistance of a clean filter in terms of how high it can suck a column of water given a particular face velocity (air speed approaching the filter). When the filter is dirty, its efficiency is great because not much can get through it, and that's when you get your final resistance. And filter resistance matters in terms of how much electricity it takes to turn your fan, so here's a page with a handy chart (pdf) of how much various resistance filters cost per day.
If you'd like to increase the amount of air you can get through your filter, you could double the area, which doubles the CFM (see page 4 here, pdf). You can't change the resistance, however, without buying a different kind of filter.
And here's how you get to the Arizona wildfire page, which I find fascinating and totally inadequate, but much better than what you'd find in the newspaper, considering the newspaper hasn't apparently even heard of this fire yet.
posted by missmolly at 9:19 PM
0 Comments:
Post a Comment
<< Home