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It I , r ~:', ~ n„ I, unpurt.uu to set the Flunu correctly
<br />il::h: ,:u;h. \l'hrn setting flume in extremely flat
<br />ditch nr under difficult conditions it is advisable to
<br />;;~; thr .I,ivicr of an experienced engineer to assure
<br />sausfactorv installation. The five following s-ug-
<br />grstim~s Till m.tkc installation of your flume easy.
<br />1. Selret a straight section of ditch with fairly
<br />high b.mla (sec Caution below).
<br />3. From previous flows locate the high water
<br />mark on the Birch bank.
<br />3. Knowing the capacity of the ditch, refer to
<br />the Frec Floc: Discharge Chart in our Parshall
<br />Flume catalog section. Then-
<br />(A) Find the throat width of your flume.
<br />(B) Folloly throat width column down until you
<br />find the discharge in cubic feet per second which is
<br />the same as the maximum capacity of the ditch.
<br />(C) Now find "Gage Reading" in outside column
<br />of page Take 70;~ of this gage-height-figure
<br />(use GO'; for 3". 6", and 9" throat widths). This is
<br />the distance which the floor of the upstream end
<br />of the flume must be placed below the high water
<br />mark on the ditch bank.
<br />(Exantplc): Assuming ditch has a maximum
<br />capacity of 6 ctt. ft. per second and the flume you
<br />are to install has a throat width of 18 inches.
<br />Referring to the Free Flow Discharge Chart you
<br />find the "gage reading" to be 1.00 foot fora capa-
<br />city of 6 cu. Et. per second through an 1S-inch
<br />throat width. i0^~ of 1.00 equals .70 feet (.70X12-
<br />8.4 inches) ci~hich is the distance the floor of the
<br />upstream end of the flume is to be set below the
<br />high water mark on the ditch.
<br />r~ee,. e. „~,,.
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<br />f-owr ni. .......a
<br />L ouven roe rnemr
<br />4. Grade I~ottom of ditch up to shape of bottom
<br />of flume and set flume in place. (Better to fill in
<br />too much then not enough to allow for settling.)
<br />5. With carpenter's level, make sure the bottom
<br />of tltc upstream end of the flame is level BOTH
<br />LENGTHWISE AND CROSSWISE. When car-
<br />penter's level shows this to be true, flume is cor-
<br />rectly installed.
<br />Caution: The flume should not be placed too
<br />near the hearlgate, or pipe discharge, as the dis-
<br />tur;,.r' ~.~~ater i~lst downstream from such outlets
<br />., ... .~~,g and unbalanced flow; it had
<br />L~- , ~ . ,,,. i:~ a su-aight section of the open
<br />c!-.~ '. •. ~ water is reasonably smooth. (Par-
<br />s) , ~ , ..,,,nr,;,g Flumes should not be installed
<br />~„ ..'. ~ l n seu::~ ,s of full-round pipe without special
<br />prcr..:utinn3, write for more information.)
<br />30th and Larimcr Streets
<br />Itt.lnl' j~1: trl 1•„Lr :, I, u}II I, IY Ia, ,n,nl, I rJ Il,c
<br />flume bnttum (rule a ligln 12-nlcll wulr: lu,ald sir.
<br />feet or more long. The edge of this board is cut
<br />exactly the shape of the base of the flame as
<br />illustrated:
<br />Using this board as a sweep, the bottom of the
<br />ditch may be easily shaped so the flume, when set
<br />in place, has a solid base its entire length. Note:
<br />If the installation is to be made in soggy ground,
<br />three pieces of railroad tie may be used, setting one
<br />piece under each end and one under the throat.
<br />After the flume has been set in place and the
<br />upstream end leveled both ways, fill in dirt around
<br />flume to hold it firmly in place. The flume is then
<br />ready to operate.
<br />To prevent washing and undercutting, riprap-
<br />ping at either or both ends may be desirable. Once
<br />the flume is solidly in place this riprapping can be
<br />done without buckling or damaging the flume. In
<br />cases where the stream has a high velocity, bottom
<br />and sides of ditch downstream from flume should
<br />be riprapped for three or four feet to prevent
<br />excessive washing.
<br />Accessories:
<br />Wing Walls: To keep
<br />water from washing
<br />away the banks or un-
<br />der-cutting the flume,
<br />steel wing walls of the
<br />same gage steel as the
<br />flume itself are avail-
<br />able. These are bolted in
<br />place at sides and bot-
<br />tom of the flume with
<br />the same type bolts and in the same manner as the
<br />flume itself is assembled. (See illustration.)
<br />Stilling Wells: Astilling i~'~°
<br />..
<br />well is used to accom- ~ ~
<br />modate an automatic de- ~
<br />vice to continuously re-
<br />cord the flow of water
<br />through a Thompson
<br />Parshall Flume. Stilling
<br />wells must be ordered at i '
<br />the time the flume is _
<br />y . .-.'
<br />ordered so that proper
<br />connections can be made at the factory. Field as-
<br />sembly is made by attaching the well to the well
<br />pipe connection at the base of the flume in section
<br />A or C and securing the strengthening cross bar
<br />at the top.
<br />G.. ~T~~L COI~PA~~(
<br />• Denver, Colorado 80201
<br />nor ,rc
<br />
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