40 BULLETIN 3*76, U. S. DEPARTMENT OP AGEICULTURE. 



DESCRIPTION OF PIPES. 



The descriptions in the following pages are to be taken as sup- 

 plementing Tables 2 and 3. The methods of determining the 

 hydraulic elements necessary for each observation are described. 

 The descriptions of pipes upon which previous experimenters have 

 made observations are given in the appendix. 



No. 13, Expt. S-12, 8-iiich Machine- Banded Douglas Fir Pipe, French 

 Brothers' Orchard, North Taliima, Wash. — From the lower end of the 10-inch 

 pipe discussed as No. 14 a reach 1,751.5 feet long of 8-inch machine-banded pipe affords 

 exceptional opportunity for investigation. This pipe conveys water to a high point 

 in the orchard, from which it is distributed in open ditches. There are two taps in 

 the line within the reach between the gauges. First is a l|-inch tap for lawn sprink- 

 ling; second, a 4-inch valve for irrigation purposes. These were closed tightly 

 throughout the tests. Gauge No. 1, a mercury manometer, was placed 219 feet from 

 the inlet valve. Gauge No. 2 was located 1,503 feet from gauge No. 1. For runs 1, 

 6, and 7 a water column was used. For runs 2, 3, 4, 5, and 8 a mercury manometer 

 was used. An 8-inch control valve is located 17.5 feet downstream from gauge No. 2. 

 A vertical iron pipe the same size as the wood pipe rises above the ground surface at 

 this valve and discharges into a wooden division box. All but one ditch leading 

 from this box were plugged with earth so that all the water was discharged at one end 

 of the division box. This was equipped with a well-made Cipolletti weir 1.05 feet 

 long. After run 3 this weir was removed and a rectangular weir, with end contrac- 

 tions suppressed, was built in its place. This weir was 2.84 feet long. Both weirs 

 had clean-cut, sharp crests of galvanized iron. The change in weirs was necessary 

 for the reason that it was desirable to run more water than could be accommodated 

 through the Cipolletti weir and still maintain so-called standard conditions. The 

 weirs were about 7 feet from the point where the water was tiorbulently discharged 

 from the 8-inch pipe. From the place of impact to within about 2 feet of the weirs 

 the box was filled with fresh-cut Cottonwood branches and leaves. This mass formed 

 an excellent screen from which the water emerged in good condition for weir measure- 

 ment. A hook-gauge reading to thousandths of a foot was placed in the box above the 

 weir. This permitted a direct comparison between the velocity in the pipe as deter- 

 mined with fluorescein and the velocity as determined by dividing the weir dis- 

 charge by the nominal area of the pipe section. This comparison is shown in Table 1. 

 The reach of pipe tested was without vertical curvature and had but one bend of about 

 20° about midway in its length. According to the best information available this 

 pipe is about 7 years old and is used about 7 months of the year. It is buried about 

 3 feet below the surface and shows no signs of decay. The pipe capacity was approxi- 

 mately 8 per cent less than the discharge computed by the new formula. 



No. 14, Expt. S-11, 10-inch Jointed Machine-Banded Douglas Fir Pipe, 

 Congdon Orchards, North Yakima, Wash. — Irrigation water for the Congdon 

 Orchards is conveyed from the main canal of the Yakima Valley Canal Co. in a 

 14-inch pipe (No. 19). From the lower end of this pipe a 10-inch pipe extends about 

 one-half mile with a right angle bend about midway. A reach 1,297.4 feet long and 

 without vertical or horizontal curvature was chosen at the lower end of the pipe, 

 which was 7 years old at time of test and appeared to be free from leakage. The 

 nominal size of the pipe was accepted as correct. Velocity was measured with 

 fluorescein, the mean velocity shown by four batches of color for each run being 

 accepted. The appearance of the color was awaited at a 6-inch hydrant 55 feet 

 downstream from gauge No. 2. The color was injected at gauge No. 1. As the intake 

 of this pipe line from the open canal is several miles from the river and the velocity 

 in the pipe is rather high, it is improbable that there was any silt in the reach tested. 



