<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Our model is based on the Exploratorium versions (which all of these are, I guess). I made a new one last year: A 250 ml erlenmeyer with stopper and about 24 inches of glass tubing inserted in stopper. At the top of the glass tubing I attached a pint-sized, clear-plastic container (Glad brand or some other disposable kind). Without water the whole thing is light enough to stand up by itself, and it is all transparent to see what's happening. To attach the little tub permanently I drilled the hole in the bottom by heating the glass and melting it through. Then I bought two small O-rings at the local hardware store that sit on the glass above and below the hole to seal it. I used some two-part epoxy to really seal the O-rings permanently to the plastic and glass (plumber's putty works too, if you want to take it apart, but it tends to leak). For the demo I use a tall ringstand to support the tub, and the flask sits on a small hotplate. I set it up so the top end of the tube about 3 cm below the rim of the tub so I can nearly fill the tub with water, get good splashing, and get quick recycling because the water in the tub stays cooler. I think the small flask also helps with quick recycling. We've been using this model for years and have never had any glass shatter. Of course, they are always Kimax or Pyrex. I always fill the model with distilled water to keep it and the surroundings free of scale and salt. <div><br class="webkit-block-placeholder"></div><div>I also model a cone type geyser very simply by putting a thick-walled, tall neck Florence flask (flat bottomed, 500 mL) on a hotplate with 50-100 mL of distilled water in it. Heat on medium-high until boiling, then jam a rubber stopper in the top and crank the heat to full and stand back. After a few tense minutes the stopper will blow off and about half the water will turn to steam, and with any luck the ceiling will get all wet too. I keep the whole thing a safe distance from my students, but I've done it 100 times with consistent results, always with the same flask that I hide away for this one purpose. I also took video of the eruptions that we analyze in slow motion. It's a crowd-pleaser.<br><div><br><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div>Craig Messerman</div></span><div><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div>Sentinel High School, Missoula, MT</div><div><br></div><div><a href="mailto:cmesserman@mcps.k12.mt.us">cmesserman@mcps.k12.mt.us</a></div><div><a href="mailto:cmflyer@bresnan.net">cmflyer@bresnan.net</a></div><div><br class="khtml-block-placeholder"></div><br class="Apple-interchange-newline"></span> </div><br><div><div>On Jan 14, 2008, at 12:22 PM, Jeff Cross wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">I will add a few things to the posts that have been written about model geysers.</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">1) Glass models are nice because you can see the steam bubbles inside the flask.</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">2) Glass is very brittle.</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">3) Glass is most likely to break at the very end of the eruption.<span class="Apple-converted-space"> </span>If you have a funnel on top of the geyser, the cool water in the funnel will get sucked back into the reservoir after the eruption ends.<span class="Apple-converted-space"> </span>The thermal shock of this cold water on the hot reservoir flask can cause the flask to shatter.<span class="Apple-converted-space"> </span>Putting boiling stones in the reservoir flask will not prevent this from happening.</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">To avoid this problem, we have used metal containers for most of our models.<span class="Apple-converted-space"> </span>You can get some 2" pipe at the hardware store.<span class="Apple-converted-space"> </span>Get the right pieces to make a T or L-shaped reservoir.<span class="Apple-converted-space"> </span>Get some reducers and put a 4-foot long standpipe on the model, maybe 1/2 or 3/8 inch diameter.<span class="Apple-converted-space"> </span>The geyser will need supports of some kind.<span class="Apple-converted-space"> </span>Try tying it to a ladder or something stable.</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Jeff Cross</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="mailto:Jeff.cross@wallawalla.edu">Jeff.cross@wallawalla.edu</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Geysers mailing list</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="mailto:Geysers@lists.wallawalla.edu">Geysers@lists.wallawalla.edu</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="https://lists.wallawalla.edu/mailman/listinfo/geysers">https://lists.wallawalla.edu/mailman/listinfo/geysers</a></div> </blockquote></div><br></div></div></body></html>