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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>Dear Crispin,<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>Yes – this is the type of thing I am looking for. They need to be heavy enough to flow down around funny looking particles. And cheap to discard after each test. Perfectly round would help as I think that is the only problem with sand once the salts are removed. Stainless shot I was thinking but likely too expensive. Steel shot picked out with a magnet but if they acted like little magnets they would be no good. <o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>Glass beads do not flow like I need them for wood chips and all the crevices. <o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>Regards<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>Frank<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Stoves [mailto:stoves-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>Crispin Pembert-Pigott<br><b>Sent:</b> Monday, March 10, 2014 2:19 PM<br><b>To:</b> 'Discussion of biomass cooking stoves'<br><b>Subject:</b> Re: [Stoves] Calc. void space and pellet particle density<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Dear Frank<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>One of the best ways to check voids is to use <a href="http://www.freepatentsonline.com/5980644.html">xenospheres</a>. You would probably want to measure their volume not the mass because they are so light. They are available ‘sized’ for example 100 microns. One company selling them was called Ash Resources in Johannesburg but I bet you can get them from a lot of places.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Xenospheres are produced when tiny silica grains are expanded in the fire of a coal burner like a power <a href="http://www.darcy.co.uk/case-studies/installation-of-debris-booms-prevents-xenospheres-getting-into-local-rivers/">station</a>. They chill and emerge as hollow spheres with a vacuum inside. They are floated off in the ash treatment and collected, size sorted and sold as filler.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If you don’t break them (they are not very strong) you have small balls that are very slippery and pretty constant in size. You can buy, for example, 80-100 microns in a bag.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I think the biggest size is 400 microns but they do get larger – just not so many of them. Light, insulating concrete products include it in the mix as if it was sand. You can add them to ceramics to make them light but most will not survive passing through a pug mill or extruder.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Regards<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Crispin<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p></div></body></html>