E-mail jerry@freeflowinc.com Phone 800-933-4818 or 402-332-4818 Fax 402-332-3036
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Free Flow H, HS & HL Flumes Free Flow H flumes were originally developed to measure agricultural water runoff. Additional applications include: irrigation water; snow melt; holding pond overflow; industrial process discharge; sanitary & storm sewer discharge. H flume sizes cover a wide range of flows. The H flumes have a V shaped design which allows a wide flow range to be measured. Good accuracy is obtained at low flow due to the small opening at the bottom of the V. The large open area at the top of the V results in a high capacity. H flumes are designed for use with an approach box immediately upstream of the flume. The boxes should have the same width & height as the flume and sufficient length to allow the flow to be evenly distributed across the width of the box. The approach section can be supplied by Free Flow or formed in the field. The inlet end of the approach box can be supplied open, or with a bulkhead and with pipe flanges or couplings to match upstream piping. For agricultural service & other water runoff measurements, the flume and approach are usually set below the natural ground surface at a location where the runoff has concentrated naturally into a small stream channel upstream of the flume. The flume floor must be level in both directions. In operation, the depth on the head gauge or in the stilling well is noted and the discharge rate is deter mined by consulting the tables. When used with continuous recording and totalizing equipment, careful cross-checking of the zero and span should be made to insure accuracy. Conditions downstream of the flume should be such that the flume has a free discharge. Custom fabricated downstream adapters are available to direct the flow to culverts or other downstream piping. H Flumes will operate in submerged flow. A submergence of 30% has less than 1% effect on the free discharge head. A 50% submergence has less than a 3% effect. Formulas and tables for correcting the discharge under submerged flow conditions are available. Free Flow H flumes are fabricated in several methods of construction and options to facilitate their installation and use. Model SC, Standard Construction, is intended for below grade installation in concrete. Model RC, Ruggedized Construction, is intended for free standing, above grade installation. Special vinyl ester resins or stainless steel construc tion are available for enhanced resistance to specific chemicals and elevated temperatures. A flush mounted head gauge in feet provides a convenient means of determining the discharge. Stilling wells provide a large calm area where the depth is easily measured. 8" or 12" dia. wells are available. The well will extend 6" below the floor of the flume. Model HS flumes are designed for the measurement of very small flows with a high degree of accuracy. Model HL flumes are designed to handle very large flows. Only the 4 foot HL flumes is recommended because the smaller flows are measured more accurately by the H flumes. Installation and operation requirements for both the HS & HL flumes are similar to
the H Flume. |
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