here's the new "limit switch" we're using to control the auger feed. we have gone round and round on solutions for this. finding something that is robust in use, easy to make or cheap to buy, flexible over fuel types, and without lots of supporting tech to install, has been very difficult.
we went through the IR LED solutions and found them too touchy and with too many wires. we've made our own straight plunger with the switch externalized and all the tensions adjustable, and it was too much to make daily. we've gone through all the regular solid materials handling solutions and found the prices not tolerable for the individual power solutions we're trying to enable, but here, finally, we found something we like.
this is a flow switch to sense moving liquids. it is fully sealed and with the electronics well separated from the inside vessel. it will take reasonable heat and has robust metal construction throughout. it comes with 4 paddle options of different lengths, all of them flexible so they spring against the fuel, helping a bit with breaking up bridges. it has a standard npt plumbing fitting so you can mount it easily in the usual npt bung on the top of gek vessels. thus, it is also backward compatible with all auger and pyrocoil versions shipped to date.
this is what we are shipping with augers and pyrocoils as of 1/21/10. we can upgrade the level switches on older gek augers at our cost for the switch unit. please write if you want/need the upgrade.
(note also that we now use a "banjo" lid to connect the auger drying bucket to the reactor. this is what is shown in the pictures below. this replaces the previous "doghouse" reactor lid. if you use the pyrocoil, you get rid of either the doghouse or banjo lid, as the pyrocoil takes its place. if you have the pyrocoil, it connects the auger drying bucket to the reactor, with the added external heat add of the pyrocoil. the auger drying bucket and pyrocoil together is what makes the Hot TOTTI.)
anyways, back on the switch. here is a good switch finally that we like.