[Stoves] Wood-fired masonry heaters - training

Frank Shields franke at cruzio.com
Sun Aug 20 15:47:42 CDT 2017


Dear Crispin, Stovers,


The HEPA filters down to 0.3 um. 

When measuring suspended solids in water the filter is 47 mm across and filters out particles > 1.5 um. The filters are pre-washed, dried and placed in a descanter. They weigh about 0.14xx grams each. Using a balance good to 0.1 mg means you need a weight of > 1 mg for an accurate actual reading (I am thinking). 


Problem:

Your filter is 100 mm diameter. Is it pre-washed or pre- air flow treated? I would think the 1 mg would be the low limit to report an accurate reading. Below that you report ‘less than 1.0 mg per air volume’. 

Your thinking of using a pump having a standard pull. Adjusted with the filter getting loaded up with particles(?). That could be tricky. And then you have the location of where the air is being pulled from. Temperature, pressure, air flow, dilution, leaks etc all needing to be factored in. You need to know the total air volume going up the stack. Any small error in one of the measurements and the final reading is blown way out of accuracy. 

Solution:

Helium is bleed in with the primary at a constant and known rate. This should be easy and accurate. 
The volume of the gasses leaving the filter paper is recorded and plotted. It is not adjusted. The gases are also tested for helium concentration and the total helium volume during the ‘run’ is determined. So now we have mg particles per liter helium. Knowing the amount of helium we bleed in with the primary we have a very accurate measure of the total particles released into the room during that time of combustion.   

Helium is easy to get in the U. S. Used for party balloons and sold in many places. Same as in other countries? 
The expense is the equipment to measure it, personal running it and maintenance. Equipping a lab with such a machine is my suggestion of where funding could go. 


Regards

Frank


 





> On Aug 20, 2017, at 11:49 AM, Crispin Pemberton-Pigott <crispinpigott at outlook.com> wrote:
> 
> Dear Andrew
> 
> The Condar uses a 100mm diameter filter. 
> 
> The links below are to ambient air machines - 1 mg limit which is pretty low. It would require a significant amount of dilution to bring it under that limit. 
> 
> The Condar works using ambient air as a dilutant, so the ambient level has to be really low. Really good stoves are so clean the diluting air has to be either very good or filtered. As LBNL found out in Ulaanbaatar, even a HEPA filter is not as good as a top line stove at removing PM. 
> 
> I am discussing a new approach using the Condar that will remove the need for dilution. It samples with a small tube maintaining a standard 'pull' from a pump. The automated ones have an electronic pressure sensor/compensator on the pump to keep it very constant. There are a couple of ways it can be done. The Dusttrak uses such a system, diluting (sheathing, actually) using the incoming gases which it first filters. 
> 
> Regards
> Crispin
> 
> 
> 
> 
> Would one of you care to expand on this Condar with a few pointers?
> 
> I've been considering inexpensive sensors for background levels and their variation as well as direct testing
> 
> 
> http://tinyurl.com/y8cmwmxv
> 
> http://tinyurl.com/y8zfhzjw
> 
> This is from Aliexpress which seems to be the retail arm of alibaba.
> 
> Andrew
> 
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Thanks

Frank
Frank Shields
Gabilan Laboratory
Keith Day Company, Inc.
1091 Madison Lane
Salinas, CA  93907
(831) 246-0417 cell
(831) 771-0126 office
fShields at keithdaycompany.com



franke at cruzio.com



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