Irrigation Systems Quiz
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Questions and Answers

What is the minimum working pressure for the nominal diameter pipes manufactured in inches?

  • 10.0 bars
  • 7.0 bars (correct)
  • 6.0 bars
  • 4.0 bars

What is a typical length provided for the pipes with aluminium quick couplings?

  • 7, 10 and 13 m
  • 6, 9 and 12 m (correct)
  • 8, 11 and 14 m
  • 5, 10 and 15 m

What is the maximum recommended flow velocity for rigid PVC pipes, according to the provided text?

  • 1.2 m/s
  • 1.5 m/s (correct)
  • 2.0 m/s
  • 1.0 m/s

What are the nominal diameters (DN) of rigid PVC pipes?

<p>50, 63, 75, 90, 110, 125, 140, 160, 200 and 225 mm (B)</p> Signup and view all the answers

What is the expected lifespan of the pipes, according to the provided text, under good management?

<p>15 years (D)</p> Signup and view all the answers

What is the primary factor determining sprinkler and lateral spacing in a periodic-move system?

<p>The extent of the field area, water source, and irrigation system type. (A)</p> Signup and view all the answers

According to Table 1, what is the maximum recommended spacing between laterals, as a percentage of the wetted diameter, in a rectangular pattern when average wind speeds are between 10-15 km/hr?

<p>60% (D)</p> Signup and view all the answers

If the average wind speed in an area is above 15 km/hr and a rectangular sprinkler pattern is used, what should be the maximum spacing between sprinklers as a percentage of the wetted diameter?

<p>30% (D)</p> Signup and view all the answers

According to Table 2, what is the maximum sprinkler spacing in a square pattern if the wind speed is between 6 and 11 km/hr, expressed as a percentage of the wetted diameter?

<p>50% (B)</p> Signup and view all the answers

What is a key consideration when selecting sprinklers for the irrigation system?

<p>Ensuring that the average application rate is lower than the soil infiltration rate. (D)</p> Signup and view all the answers

What is the relationship between average wind speed and the percentage of wetted diameter used for spacing in a rectangular pattern, based on Table 1?

<p>As wind speed increases, spacing between sprinklers and laterals decreases. (C)</p> Signup and view all the answers

If a field requires a square sprinkler pattern and the wind speed is consistently between 13-19 km/hr, what should be the target spacing between sprinklers as a percentage of the wetted diameter, according to Table 2?

<p>45% (C)</p> Signup and view all the answers

What adjustment would you make to the spacing between sprinklers in a rectangular pattern if the wind speed increases from 10km/hr to 16km/hr?

<p>Decrease lateral and sprinkler spacing, as percentage of wetted diameter (A)</p> Signup and view all the answers

What is the typical length of steel threaded pipes supplied for sprinkler systems?

<p>6 meters (C)</p> Signup and view all the answers

What is the primary disadvantage of using plastic pipes compared to steel pipes in sprinkler systems?

<p>They suffer a continuous creep strength (A)</p> Signup and view all the answers

Which type of pipe is most suitable for moveable lateral lines in sprinkler irrigation?

<p>Quick coupling aluminum pipes (B)</p> Signup and view all the answers

For which application are steel threaded pipes most often used in sprinkler systems?

<p>Risers and connector tubes (C)</p> Signup and view all the answers

What is the primary function of thrust blocks in underground PVC pipelines?

<p>To prevent movement of fittings and valves due to water pressure. (B)</p> Signup and view all the answers

What is the estimated average lifespan of welded hot-dip galvanized steel pipes when used on the surface in the atmosphere?

<p>15-20 years (B)</p> Signup and view all the answers

What is a key advantage of using quick coupling light steel pipes in sprinkler systems?

<p>They are easy to install and remove (A)</p> Signup and view all the answers

What is the purpose of adding 2.5 percent carbon black to polyethylene pipes?

<p>To protect against ageing and damage from sunlight and temperature fluctuations. (C)</p> Signup and view all the answers

What is the typical jointing method for small-diameter uPVC pipes (up to 50 mm)?

<p>Solvent cement welding. (B)</p> Signup and view all the answers

What are the typical diameters (DN) available for quick coupling light steel pipes, as mentioned in the document?

<p>70, 76, and 89 mm (C)</p> Signup and view all the answers

What is the estimated average lifespan for buried uPVC pipes?

<p>50 years. (A)</p> Signup and view all the answers

Compared to light steel pipes, approximately how much lighter are quick coupling aluminum pipes?

<p>About half the weight (D)</p> Signup and view all the answers

Which type of polyethylene pipe is typically used for micro-emitter laterals?

<p>LDPE (Low-Density Polyethylene). (A)</p> Signup and view all the answers

Which of the following is NOT a required detail on a topographic map for a center pivot irrigation system?

<p>Location of potential customers for the produce (A)</p> Signup and view all the answers

What does 'available moisture' refer to in the context of calculating the net depth of water application?

<p>The difference between field capacity and permanent wilting point (C)</p> Signup and view all the answers

Which parameter does 'drz' represent in the net depth of water application equation?

<p>The depth of the root zone (D)</p> Signup and view all the answers

What does 'peak $ET_a$' refer to when calculating irrigation frequency?

<p>Evapotranspiration rate at its maximum (C)</p> Signup and view all the answers

In calculating the gross depth of water application, what is 'Ea'?

<p>The application efficiency of the irrigation system (D)</p> Signup and view all the answers

What units are used to calculate the preliminary system capacity ($Q_{prelim}$)?

<p>cubic meters per hour (C)</p> Signup and view all the answers

What is the role of 'Nshift' in the preliminary system capacity equation?

<p>The number of shifts per day (B)</p> Signup and view all the answers

If the net depth of water application ($d_{net}$) is 60 mm and the peak $ET_a$ is 10 mm/day, what is the irrigation frequency ($I_f$)?

<p>6 days (C)</p> Signup and view all the answers

Given a net depth of water application of 50 mm and an application efficiency of 0.8, what will be the gross depth of water application ($d_{gross}$)?

<p>62.5 mm (A)</p> Signup and view all the answers

Which of the following data is NOT directly involved in calculating preliminary system capacity?

<p>Distance to the nearest city (B)</p> Signup and view all the answers

What is the expected service life of a plastic pipe laid on the surface?

<p>12-15 years (C)</p> Signup and view all the answers

Which of these is NOT a standard size (external diameter) in millimeters for plastic pipes?

<p>55 (D)</p> Signup and view all the answers

What is the maximum recommended flow velocity in plastic pipes?

<p>1.5 m/s (B)</p> Signup and view all the answers

What material is layflat hose made of?

<p>Soft PVC reinforced with interwoven polyester yarn (C)</p> Signup and view all the answers

What are the standard lengths that layflat hoses are supplied in?

<p>25, 50 and 100 m (D)</p> Signup and view all the answers

According to the sample computation, what was the calculated net depth of water application for a tomato crop?

<p>43.2 mm (A)</p> Signup and view all the answers

In the sample computation, what is the calculated irrigation frequency?

<p>8 days (B)</p> Signup and view all the answers

According to the sample computation for the side-roll system, what is the value used for the root zone depth when calculating the net depth of water application?

<p>0.9 m (D)</p> Signup and view all the answers

Flashcards

Available Moisture (FC-PWP)

The difference between field capacity and permanent wilting point, representing the amount of water available for plant use. It's crucial for calculating irrigation needs.

Depth of Root Zone (drz)

The depth of soil where plant roots can access water. It influences how much water is needed for irrigation.

Allowable Moisture Depletion (MAD)

The percentage of available moisture that is allowed to be depleted before re-irrigation. It ensures sufficient water for plant growth while preventing excessive water stress.

Net Depth of Water Application (dnet)

The net depth of water application, determined by the available moisture, root zone depth, and allowable moisture depletion. It represents the actual water needed by the plants.

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Irrigation Frequency (If)

The frequency at which irrigation is needed, calculated based on the net depth of water application and the actual evapotranspiration at peak demand. It ensures timely water supply to meet plant needs.

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Actual Evapotranspiration (ETa)

The rate of water loss from the soil due to evaporation and plant transpiration at the peak of the growing season. It helps determine the required irrigation frequency.

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Gross Depth of Water Application (dgross)

The total depth of water applied to the soil, accounting for application efficiency. It considers water losses due to evaporation and runoff.

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Application Efficiency (Ea)

The efficiency of the irrigation system, representing the proportion of applied water that reaches the root zone. It influences the gross depth of water application.

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Preliminary System Capacity (Qprelim)

The estimated capacity of the irrigation system, calculated based on the design area, gross depth of water application, irrigation frequency, number of shifts per day, and irrigation time per shift. It provides initial sizing estimates for the system.

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Center Pivot Sprinkler System

A type of sprinkler system where the sprinkler booms move in a circular pattern around a central pivot point, providing efficient irrigation coverage. They are commonly used in large fields with uniform soil conditions.

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Thrust blocking

PVC pipes should be secured to prevent movement caused by water pressure.

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LDPE

This type of pipe is flexible and often used for small emitters due to its lower density.

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HDPE

These pipes are more rigid and are used for main lines, submains, and manifolds. They are stronger due to their high density.

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Coil Length for PE Pipes

The length of pre-manufactured polyethylene pipes.

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Minimum depth of cover for PVC pipes

The minimum depth of cover protects the pipe from damage and freezing.

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Steel Pipe Advantages

Steel pipes are durable and withstand high pressures unlike plastic pipes that degrade over time.

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Steel Pipe Applications

Steel pipes are mainly used for risers in hydrants and connectors for head control units, where strength is crucial.

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Steel Pipe Specifications

Steel pipes are available in various sizes (DN) and pressure ratings (classes) based on standards like ISO R-65, BS 1387, DIN 2440/41/42.

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Steel Pipe Assembly

Steel pipes are supplied in 6-meter lengths and joined together with threaded joints for permanent installations.

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Steel Pipe Lifespan

Hot-dip galvanized steel pipes have an average lifespan of 15-20 years above ground and 10-15 years in soil, depending on the soil's properties.

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Quick Coupling Steel Pipes

Quick coupling light steel pipes are lightweight, easy to install and remove, suitable for mains, submains, feeder lines, and laterals.

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Quick Coupling Steel Pipe Sizes

Quick coupling light steel pipes are available in diameters of 70, 76, and 89 mm, suitable for farm-level pressure irrigation.

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Aluminum Pipes

Aluminum pipes are light, strong, and used above ground as movable lateral lines in portable sprinkler installations.

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Sprinkler spacing and Lateral movement

The distance between sprinklers and the distance between laterals (rows of sprinklers) depends on water source, sprinkler type, and field size, especially considering wind.

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Wind impact on sprinkler spacing

Tables 1 and 2 suggest spacing based on wind speeds for rectangular and square sprinkler patterns. The higher the wind, the closer the sprinklers need to be.

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Sprinkler size and spacing

Table 3 shows an example of sprinkler spacing based on the sprinkler’s size, determined by the manufacturer.

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Irrigation Period

The length of time that the sprinkler system runs, calculated based on how much water is applied to the area and the distance between sprinklers.

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Choosing the right sprinkler

Select sprinklers that can cover the whole field area evenly and apply water at a rate that is slower than the rate at which the soil absorbs water.

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Application rate

This ensures that the soil isn’t over-saturated, which can lead to problems like runoff and poor plant growth.

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Application rate

The amount of water that falls in a specific area over a given time. The application rate should be less than the rate at which the soil absorbs water.

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Soil infiltration rate

The rate (speed) at which water infiltrates into the soil, allowing it to soak in. The sprinkler’s rate should be less than this.

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What are the standard lengths and coupling types for aluminum irrigation pipes?

Aluminum quick couplings are either detachable using clamps and rings or permanently fixed to the tubes. They come in standard lengths of 6, 9, and 12 meters.

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What are the minimum working pressures for aluminum irrigation pipes?

The minimum working pressure for aluminum irrigation pipes is 7.0 bars. In the metric series, sizes are 50, 75, 100, 125 mm with working pressures of 4.0, 10.0, and 16.0 bars.

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What are the typical diameters of aluminum irrigation pipes?

They come in nominal diameters of 2, 3, 4, 5, and 6 inches (51, 76, 102, 127, and 159 mm).

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What are the uses of uPVC pipes?

uPVC pipes are ideal for irrigation, water conveyance, and distribution lines as mains and submains. They are frequently used as manifolds and laterals.

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What are the limitations on flow velocity and standard length for uPVC pipes?

The maximum flow velocity of uPVC pipes should not exceed 1.5 m/s. These pipes are manufactured in standard lengths of 6m.

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Service life

The time it takes for a material to become unusable due to wear and tear, aging, or other factors.

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DN (External Diameter)

Refers to the outermost diameter of a pipe, used for sizing and fitting.

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PN (Working Pressure)

The maximum pressure a pipe can withstand during operation without failing.

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Maximum flow velocity in plastic pipes

The speed of water flowing through a pipe, crucial for efficient and safe water delivery.

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Layflat hose

A flexible and lightweight pipe used for surface irrigation, offering an alternative to rigid PVC pipes.

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Layflat hose material

A strong material made of soft PVC with interwoven polyester yarn, providing flexibility and durability.

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Plain Ends of a Layflat Hose

The ends of the hose are used for connecting it to other parts of the irrigation system.

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Small diameter PE tubes

Smaller diameter PE tubes used to connect side-branches to the main layflat hose.

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Study Notes

Philippine National Standard: Design of a Pressurized Irrigation System - Part A: Sprinkler Irrigation

  • This standard provides minimum requirements, criteria, and procedures for designing periodic-move and continuous-move sprinkler irrigation systems.
  • References used in the standard include PNS/BAFS/PAES 217:2017 (Determination of Irrigation Water Requirements).
  • Key terms defined for the standard include average pressure, design pressure, distribution uniformity, irrigation period, and sprinkler irrigation.
  • Sprinkler spacing is the distance between two sprinkler heads.
  • Wetted diameter is the diameter of the circular area wetted by a sprinkler at a given pressure and no wind.
  • Components of a sprinkler irrigation system include pump units, filtration systems, and sprinklers. Mainlines and sub-mainlines deliver water from the pump unit to the laterals; laterals deliver water from the mainlines or sub-mainlines to the sprinklers.
  • Criteria for sprinkler irrigation system design include crop type (sprinkler irrigation is suitable for crops and trees where water can be sprayed over or under the crop canopy). Irrigation should also minimize pressure changes at the sprinklers to ensure uniform irrigation. The soil type is also important. Sprinkler irrigation should not be used on soils with low infiltration rates. Soil types that form crusts are also not suitable.
  • Important considerations in sprinkler irrigation are the irrigation water quality (water should be free of suspended sediments), and soil and slope types.
  • Different sprinkler systems are discussed. Set systems (fixed sprinklers) and periodic-move systems (maneuverable sprinklers—hand-move and mechanical-move) are described. Continuous-move systems are also detailed, such as center-pivot and linear-move, and sprinkler spacing based on various wind conditions is covered.
  • Data requirements for designing sprinkler systems include a topographic map, water resources data, climate data, and soil characteristics.
  • Procedures are provided to calculate net depth of water application, irrigation frequency at peak demand, gross depth of water application, and preliminary system capacity for sprinklers systems.
  • The standard details the final design procedure, including lateral movement, sprinkler selection, system capacity, the determination of pipe sizes, and the selection of other components.
  • Specific considerations for continuous-move sprinkler systems are also addressed.
  • Recommended materials for different parts of the sprinkler system (mainlines, submainlines, and laterals) are listed.
  • Types of sprinklers, including impact sprinklers and rotor sprinklers, are explained, including their key features and operation.

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Test your knowledge on the specifications and requirements for irrigation systems, including pipe dimensions, flow velocities, and optimal sprinkler spacing. This quiz covers key concepts from irrigation management and engineering standards.

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