. Bulletin of the Department of Agriculture. Agriculture; Agriculture. USE OF CONCRETE PIPE IX IRRIGATION. 31 open stands made of concrete pipe cemented together may be used for this purpose. The water will rise in the pipe connected to the inlet, and flow over a crest or notch into the other pipe, and thence into the main (figs. 8 and 9). The lateral pipe leading from this stand requires no gate, as the pressure will remain constant, allowing no excessive pressures to accumulate in the lateral. If a lateral slopes down grade from an overflow stand it is usual to provide a shut-off gate w
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. USE OF CONCRETE PIPE IX IRRIGATION. 31 open stands made of concrete pipe cemented together may be used for this purpose. The water will rise in the pipe connected to the inlet, and flow over a crest or notch into the other pipe, and thence into the main (figs. 8 and 9). The lateral pipe leading from this stand requires no gate, as the pressure will remain constant, allowing no excessive pressures to accumulate in the lateral. If a lateral slopes down grade from an overflow stand it is usual to provide a shut-off gate where the lateral branches off from the stand. The gate may be set in a low auxiliary stand that is cemented to the side of the main relief stand. Some relief stands consist of one large stand/pipe of suffi- c i e n t diameter to allow an overflow pipe being placed in- side of it (fig. 10). Some orchard lat- erals have a 12-inch stand 6 to 18 feet high fitted with a 6- inch spillway pipe inside, the 6-inch pipe extending to a foot or so of the top of the 12-inch pipe. In this case water is diverted to the side lateral from the 12- inch pipe, the excess of water spilling down the 6-inch pipe into the main. There are a number of modifications of this principle that will be taken up in detail under the subject of diversion boxes and pipe structures. Nearly all measuring devices act as relief stands, especially weirs, miner's-inch boxes, and ordinary recording irrigation meters, as such devices are installed to allow the free flow of water over a crest in an open box. MEASURING DEVICES FOR PIPE IRRIGATION SYSTEMS. A number of devices are in use to measure the flow of water through pipes and laterals and from pumping plants and reservoirs. Of these the following are briefly discussed—Venturi meters, weirs,. Fig. 9.—Overflow pipe in rear and small diversion box in Please note that these images are extracted from scanned page images that may have been digitally enhanced for
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