Joining the legions of the undead

Though I’m pretty sure a good number of my dear readers would probably love nothing better than for me to join the legions of the dead, I’m not quite that far gone yet. I shall be sticking around in order to be a constant irritant to those that dislike me. In fact, should my current miserable virus be bad enough to cause me to get near deaths door, I’ve arranged to remain undead. That should bring fear to the hearts of my enemies, whose livers I shall savour with fava beans and a nice Chianti.

Yes, I’ve fallen victim to one of the viruses my passengers has brought aboard on my work bus. As those of you in the know, know, I drive a special needs schoolbus. So, I drive from 5:40am til 8:45am then again from 1:30pm to 4:50pm and while the children have the benefit of air conditioning, I sweat it out at the driving seat in 90F. By the time I’ve done for the day I’m usually a little unsteady on my feet.

This weekend is an almost lost weekend as far as I’m concerned. I can’t go far or do much. Thank heavens it’s the weekend though and I’m not missing work. I did make it to the bus for ten minutes and though it’s 73F, those ten minutes almost did me in!

This is a spare bilge blower and I wanted to see how much difference my mosquito mesh filters would make to airflow. I have a feeling my existing exhaust vents and mesh filters could be causing a problem with throughput. Thus, using my anemometer and a spare 12v battery, I experimented and recorded the results below.

First I tried measuring outflow then I measured inflow both with and without meshes. Now I don’t regard my eBay anemometer as being the best tool out there. It was cheap and can be used as a rough estimation of airflow. My fan is rated at 130 cubic feet per minute. The anemometer is rated at feet per second. There’s a disparity of measurement that I can’t be bothered to calculate.

Needless to say, with no filters I got about 2200 feet per second. With two meshes I got just over half at 1400 feet per second. Then things get interesting. It seems the fan is more efficient when blowing than when sucking. The blow rate was 1600/1400 feet per second versus the suck rate of 1400/1200 feet per second. That goes against all the online mumbo jumbo that I’ve ever read. I can’t argue with my figures - they’re there in black and white.

Now, assuming I use a more appropriately sized large mesh for the inlet and no mesh for the outlet, I should get a throughput of 2200fps. Using two 130CFM fans I should be able to evacuate all the air from the bus in just over 4 minutes. That sounds promising.

I currently have mushroom vents over my vent pipes. If I were to replace them with flapper vents, that would increase airflow though I’d still need some kind of hood to prevent the wind from opening the flappers enough to allow critters inside. I’ve already noticed that with my mushroom vents, I get air blowing in when the fan is turned off.  I shall have to investigate flapper vents further.