PNS/BAFS/PAES 223:2017

Design of a Pressurized Irrigation System – Part A: Sprinkler Irrigation

PNS/BAFS/PAES 223:2017

average sprinkler pressure of a lateral

average pressure

pressure required to overcome the elevation difference between the water source and the sprinkler nozzle, to counteract friction losses and to provide adequate pressure at the nozzle for good water distribution

design pressure

numerical value on the uniformity of application for agricultural irrigation systems

distribution uniformity

time required to cover an area with one application of water

irrigation period

delivers water from the source to the pipe system at an adequate capacity

pump unit

consists of screen openings considerably lower than the nozzle diameter to prevent nozzles from clogging

filtration system

device of various nozzle sizes which sprays water over the ground or crop.

sprinkler

pipes which convey water from the pump to the laterals

Mainline and Submainlines

deliver water from the mainlines or submainlines to the sprinklers

lateral

type of sprinkler usually made of brass, stainless steel, aluminium and heavy duty plastic

impact sprinkler

type of sprinkler which are mostly used for landscape irrigation

Gear-driven sprinklers

type of sprinkler used for solid set, portable and semi-portable systems in agriculture as well as for landscape irrigation

rotor-type sprinklers

type of sprinkler with built-in flow controller, making it suitable for undulating terrain. It also has no moving parts and a unique flow pattern.

stationary sprinkler

Stationary sprinkler has nominal discharge covering the range of

280 to 1400 l/hr

The application rate shall always be _______ the basic infiltration rate of the soil.

less than

_______ shall be laid up and downhill.

Mainlines

______ shall be laid across slope or nearly on the counter.

Laterals

For multiple lateral operation, lateral pipe sizes shall be limited to not more than _____ diameters.

two

Sprinkler irrigation is not suitable for soils with an intake rate of less than ______ .

3 mm/hr

operate with sprinklers set in a fixed position

set system

sprinklers operate while moving in either a circular or straight path.

Continuous Move System

sprinklers that must be moved manually through a series of positions during the course of irrigation

Periodic-Move System

composed of portable or buried pipe with valve outlets at intervals for attaching the portable laterals.

Hand-Move System

Side-roll lateral system, End-tow lateral system, Gun and boom sprinkler system

Mechanical-Move System

Portable, Semi-portable, Drag-hose type

Hand-Move System

the lateral pipes are rigidly coupled and each joint of pipe is supported by a large wheel where the lateral line forms the axle for the wheels. This is mechanically moved by an engine mounted at the center of the line.

Side-roll lateral system

consists of rigidly coupled lateral pipe connected to a buried mainline positioned in the center of the field. Laterals are towed lengthwise over the mainline from one side to the other in an “s” form

End-tow lateral system

–nozzles are attached to long discharge tubes and rotated by means of a rocker arm drive

Gun and boom sprinkler system

Solid-set, Permanent Buried, Sequencing-Valve Laterals

Fixed System

Maximum sprinkler spacing for wind speed of up to 10 kph (rectangular pattern)

40% between sprinklers, 65% between laterals

Maximum sprinkler spacing for wind speed of 10-15 kph (rectangular pattern)

40% between sprinklers, 60% between laterals

Maximum sprinkler spacing for wind speed of above 15 kph (rectangular pattern)

30% between sprinklers, 50% between laterals

Maximum sprinkler spacing for wind speed of up to 5 kph (square pattern)

55%

Maximum sprinkler spacing for wind speed of 6-11 kph (square pattern)

50%

Maximum sprinkler spacing for wind speed of above 13-19 kph (square pattern)

45%

The total pressure variation in the laterals, if practicable shall not be more than _____ of the design pressure.

10%

The allowable friction loss in the laterals is _____ of the average pressure.

20%

The velocity in the main line shall be less than or equal to _____

2 m/s

Standard pipe length

6m

Maximum flow velocity for rigid PVC pipes should not exceed

1.5 m/s

Maximum flow velocity in the plastic pipes should not exceed _____

1.5 m/s