IRRIGATION m FLORIDA, 



57 



Begin laying pipe at intake end, with socket end of the pipe pointing forward. 

 Round out bottom of trench to fit body of pipe and cut roomy depressions for 

 sockets and entrance of hands in making joints. 



Place rope of oakum around spigot end of each pipe and shove pipe and oakum 

 together into socket. Prevent oakum from getting between end of pipe and 

 shoulder of socket. Oakum is used to center the spigot in the socket and pre- 

 vent the mortar from working inside of the pipe line. Drive oakum against the 

 socket shoulder with a hand tamper. Lay several hundred feet with oakum 

 before mixing joint mortar, taking care that each joint has a complete, even, 

 annular space for mortar. 



Mix joint mortar one part of Portland cement to one part of clean, sharp, fine 

 sand. Mix the materials dry until they have uniform color, then wet to a stiff 

 consistency which will permit the mortar being driven into the joint with an 

 iron hand tamper without pressing out at any point. 



Place mortar in joints, using light-weight rubber mittens, tamp firmly, making 

 sure lower side of socket is filled, trowel off mortar, making a smooth shoulder, 

 and immediately cover joint with moist earth. 



Completely fill trench before rain occurs to prevent trench filling with water 

 and floating the pipe line. 



If the above specifications are followed there will be no trouble 

 from leaks, provided the sand and cement are of good quality and 

 care is exercised to prevent excessive pressure on the pipe. It must 

 be remembered that this is low-pressure pipe and the design should 

 take this into consideration. It is a safe rule to keep the pressure 

 head between 5 and 15 feet. There should be a relief stand at some 

 convenient point, and if the grove to be watered is a large one, it may 

 be necessary to have several of these. 



In determining the size of terra-cotta pipe to be used it should be 

 remembered that to obtain the same flow through a small pipe that 

 may be obtained with one of larger size will call for increased pres- 

 sure. Approximate friction factors which are sufficiently close for 

 preliminary estimates can be found in most of the pump or pipe cata- 

 logues published by various manufacturers. The following may be 

 taken as an example : The friction of 500 gallons per minute through 

 an 8-inch pipe is about equal to 0.6 foot per 100 feet of length. Thus, 

 if 1,000 feet of this pipe were laid on a level, a pressure equal to 6 

 feet of head would be required to force the 500 gallons through the 

 line. This would call for a pressure equivalent to a column of water 

 6 feet high at the intake of the pipe. An extra head of 3 to 5 feet 

 should then be added to force delivery of the water. The factors of 

 length and elevation must be considered carefully, and the services of 

 an engineer should be obtained before the sizes of pipe to be used are 

 finally decided upon. As a rule, nothing smaller than the following 

 sizes of terra-cotta pipe should be used for the discharges indicated : 



Table 3. — Size of terra-cotta pipe according to amount of discharge of water. 



Quantity of water gallons per minute . . 



Size of terra-cotta pipe to use inches. . 



300 



500 



1,000 



1,500 



3,000 



6 



8 



10 



12 



15 



