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<br />float alarms. anI important in estimating how severe the flood <br />will be. <br /> <br />All phone numbers are dialed an~ messages played, <br />regardless of whet:h,er individual phones ar.3: answered. The tape <br />dialer will rusot lifter all of the messagas Il1ave been played. <br />As long as thu ~lal::Elr level in the stillin'St well remains above <br />the float, it wJ.:U. not reactivate. The aliarm will reactivate <br />if the river stagE' falls below the float l.~vel and rises again. <br /> <br />5.1.2 Alarm SequE,n,:es <br />Due to t:l1e clesign of the Ademco 61:l alarm dialer, the <br />lower alarm Cil~uit must be broken in D~der to enable the <br />upper alarm to activate during a flood. The middle float <br />switch, which is nO:C1IIally closed when at r.~st, breaks the lower <br />circuit as it tips. While the water is above the middle float, <br />only the upper alarm circuit can close. After the water <br />recedes below ttlEI lldddle float fOllowing ':J1e flood crest, the <br />lower alarm circuit will again be closed. This will result in <br />a second low sta'.e alarm after a flood cref;t has passed. <br /> <br />5.1.3 Use of ,a See,md Low stage Alarm <br />5.1.3.1 When two low stage alarms are receiv,ed without a high <br />stage alarm, it ~r:i.ll mean one of two thin'Js. One possibility <br />is that the wate:r rose above the middle flc>at but not up to the <br />high stage alam., and then fell below the lDiddle float again. <br />This would resal1: in two closures of the lmiler alarm circuit. <br /> <br />The second possibility is that t~~ river level rose <br />above the lower float, fell back below the lower float and <br />then rose again. Only a visual readin~ of the staff gage <br />would allow the flo,;>d coordinator to deteralin,a which condition <br />generated the l:wc> successive lower alarms. <br /> <br />5.1.3.2 When a low stage alarm is follo~ed by a high stage <br />alarm and then ,il. second low stage alarm,. i1: means that the <br />flood crest has passed the flood alarm gage. In that <br />sequence, the sel~ond low stage alarm will ,::iccur when the flood <br />water falls below 'I:he middle float as flooding recedes. <br /> <br />Note that t:l1eriver could rapidly rif;~ a,gain in response <br />to more rain, and another high stage alarm may occur. If <br />another high stage alarm occurs after the' sequence described <br />above, the river Inust be watched very clcsely. The already- <br />swollen river ccmld rise above flood sta'Je at a much faster <br />rate than indic:at:ed by Table 3. <br /> <br />5.2 Flood Warning Procedure <br />5.2.1 TheoretJ.c2Ll nood warning times <br />Float settings - The settings presel1ted in Table 2 are <br />the stages of the, floats as defined by elt!vations above mean <br />sea level. Information on changing the float settings is <br />provided in Part 6.9. The stage of t~e middle float is <br />flexible, but Im~;1: be far enough away from thE' upper and lower <br /> <br />20 <br />