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<br />insulah:d l:'xhausltubc 10 release liquid propane. a <br />(}articular lype of nozzle al the end, lmd a rcmolely- <br />cOnlrollcd onIolT value in the tubing. Inclusion of a <br />temperalure sensnr immedialely beyond Ihe nozzle <br />and a llowmetcr in thc c,hausl tube provide <br />monilonng Ihat propane is ind<.'Cd being dispensed <br />and al the dt-sired rate. Propane dispensers ha..'c <br />pro,,'en 10 be: very reliable lx-causc: of their simplicity. <br /> <br />In conlrosl. radio-controlled Agl generators an~ much <br />mnre complex, su~eplible to clogging from highly <br />corrosive seeding solutions. They an: seldom <br />equipped 10 monilor aclual Agl-in-solution l10w rate <br />bUlonly l1ame lemperature. Therefore, one cannol <br />be certain from afar that Agl was aClulllly relellscd <br />which has somelimes becn demonstrated 10 be a <br />serious probkm. <br /> <br /> <br />-.... <br /> <br />FiKU~ 3. The hitch n:solulion prt:Clpllatiun gaugc althe nonh control silc \Oo'lth the ..icw lowanlthe nonh. In Ihis pil:ture, gauge <br />dala [OHier dala are being tlownloadl-d to I ponable Palm Pilot devite. The 12-1I'Ich diameter gauge orifice IS surrounded by an <br />Aller-Iype wind shield mati.: of c1ellr Leun plas!ll:. <br /> <br />A Goodril:h icing rate sensor. similar 10 the <br />freeling rain sensors used in the national network of <br />AutotT\llled Surface Obsen'ing System (ASOS) <br />weal her stations. was usoo to dl-clare beginnings of 2 <br />hour e1l.perimenlal periods containing a pair of -10 <br />minute EUs plus theIr 20 minute butTers. This device <br />has a 1 inch high by 1/4 inch diameter sensing rod <br />extending \"Crtically from a cone-shaped slruclure. <br />!loth were automatically heateJ once rime ice <br />buildup on the rod reJuced its frequency by II preset <br />amount. The liAS data logger moniton:d I minute <br />frequency observations from the (i\Xldrich sensor. <br />The frequency had 10 dccrca'lC over a to minute <br />period by at least a s~"Cllied amoun!. t'qui\'aknllo <br />about 0.005 inch thickness of nme ice buildup from <br />SLW dropkls ffl,,(,7ing on lhe sampling rod, in order <br />for an experimental period 10 bc declared by Ihe data <br />logger program. The 10 minutc perilld provided a <br />reasonable time sample and minimiled the impact of <br />any frL"qUenll' noise spikes. Alter the lir.;t EU ora <br />pair WllS randllmly declared a.~ eilher seeded or <br /> <br />nonseedL-d. lhe opposite decision was used lor the <br />second EU of the pair. The icing sen~rcontlllut-d to <br />be monitored thwughoutlhe 2 huur period. <br />1I0wever, lhe ~nsor frequency output was not uscd <br />10 test conditions for stan of another EU pair until <br />two full hours had pa.<;;sed. A following pair wuuld be <br />declared as SlXln the required rime ice buildup again <br />occurrL-d. sometimes immediately aller Ihe tin;t2 <br />hour period ifSLW was still present. At lhe other <br />extreme, if a storm had L'tIded. the nexl EU rair <br />would nOI be declared until the nel(t storm period <br />with sulTicient SLW. perhaps days or sometimes <br />weekslaler. <br /> <br />The randomil<.-d seeding e1l.periment was totally <br />automated. requiring no human decisions or <br />inten'ention except for routine equipment <br />maintenance. ConscquL'tItly, experimentlltion was <br />conducted on II 24'" basis which maximiled lhe <br />resulting population sile of seeded and nunSL-.:dl-d <br />experimental unils. The propane cl(periment was <br /> <br />5 <br />