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Texas Licensed Irrigator Certification

Exam Review Questions and Answers

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David Mungai [Date] [Course title]

Texas Licensed Irrigator Certification

Exam Review Questions and

Answers 100%Pass

Irrigation Supplying of water to land through artificial means What are the 2 types of irrigation systems

1. Sprinkler Irrigation
2. Trickle Irrigation Sprinkler Irrigation applies water under pressure through a delivery system that delivers the water over the top of plants Trickle Irrigation supplies water directly to the root zone of the plants. The delivery system is low pressure and may be placed on top or within the soil Sprinkler Head the device through which water leaves the pipe and is propelled onto the lawns or plantings. Spray Pattern the specific distribution pattern of a specific sprinkler head Spray Head One of two types of sprinkler heads. Spray heads are stationary and made of two parts, the sprinkler body and the spray nozzle. The Nozzles control the amount of water that leaves the spray head as well as the spray pattern. Rotary Heads One of two types of sprinkler heads. Rotary heads are more in a circle and propel water in tiny streams under pressure. Rotary heads can distribute water much further than spray heads can What are the 2 types of sprinkler heads?

Micro Spray Heads Similar to the spray-heads, but with a discharge rate more like that of an emitter in (GPH). The diameter of water throw is considerably reduced. It is used for small specialized areas of the landscape such as flower beds and groundcover plantings. Irrigation Pipe Used for sprinkler irrigation systems, there are two types of pipe currently popular due to their superiority over metal pipe. Polyethylene pipe (PE) and Polyvinyl Chloride pipe (PVC) are widely used both separately and together. Scheduled Rated Pipe A PVC pipe used as a covering or sleeve for thinner, weaker pipe when it passes beneath walks, roads, driveways, or walls. The higher the schedule rating is, the stronger the pipe will be. Pressure Rated Pipe A PVC pipe used to carry the water through an irrigation system. It is produced in 4 forms. Each form is guaranteed to withstand a particular water pressure of either 125, 160, 200, or 315 pounds per square inch (PSI). Drip Tubing Used for trickle irrigation systems, the thin black rubber carries the water to emitters. It is usually black in color and made of plastic. Flow The movement of water through the irrigation system Friction Loss The loss of pressure during water flow that results from the increasing speed of the water, the increasing length of the pipe , and the roughness of the lining of the pipe. Velocity The rate of flow, as expressed in feet of movement per second. For landscape irrigation, the ideal velocity of water is 5 feet per second. Surge Pressure

A shock wave type of pressure that results when water velocity is too high and then is suddenly stopped. Excessive surge pressure over time will weaken the pipe and connections with an irrigation system. Static Pressure The pressure (in PSI) that is present in a closed system, when water is not flowing. Dynamic Pressure The pressure (in PSI) that is present at any one point in a system as a given quantity of water flows past that point. Dynamic water pressure varies within an irrigation system due to the rise and fall of water as the pipes move up and down across a landscape. Friction losses within the pipes also affect dynamic pressure. What can Spray heads do? They are generally pop-up types that are recessed below mower level when not in use. Nozzles may distribute water in a full circle, half circle, or quarter circle. They can also deliver water at standard volumes or lower gallonages. They can propel water outward to a distance of only 14 to 16 feet without the pattern being interrupted. What can Rotary Heads do? They have moving parts and they may or may not pop up. They all move in full or partial circles and propel water further than spray heads, but not as quickly. They can throw water 110 feet or more from the nozzle. Precipitation Rate Formula PR = Total GPM of an area X 96.3/ Square footage of the area What affects the rate of absorption? The more clay, slower the absorption. The more sands, faster the absorption Sizing Irrigation Pipe The pipe is one of the most expensive factors in the price of an irrigation system. The larger the pipe diameter, the more costly it will be. They will be larger in diameter near the water source and smaller as they are needed away from the water source.

the flow of irrigation water. What will be the static pressure at the valve? Static Pressure at Valve = Static Pressure at Main Line + Elevation Change X 0.433 PSI = 60 PSI + 15(0.433 PSI) = 60 PSI + 6. = 66.5 PSI Moving Water Pressure = Static pressure in the main line; - the pressure loss in the water meter, the friction loss in the pipe, the pressure loss in valves and fitting; +/- elevation pressure gains. What controls the area that is covered by the Sprinkler? type of sprinkler head, either circular or rectangular. The size of the sprinkler head and the trajectory of the spray are responsible for the area that is covered Trajectory is the path of the water as it is propelled through the air. Flat or low trajectories are used in ground cover and beneath shrubs in in planting beds. Higher trajectories are used for lawns and for plantings that are watered from overhead. Positioning of Sprinklers usually set up in a square or triangular pattern. Triangular are preferred because they give more even water distribution and waste less water. Each sprinkler delivers the full amount of water to only 2/3 of its diameter. When is a trickle irrigation system useful? in any situation where slow water application is preferable to sprinkler irrigation due to constraint of space, budget or limited water supply. What is the difference between Pressure Compensating and Non Compensating Emitters? is based upon their ability or inability to deliver a constant GPH over a wide range of water pressures. In landscapes with rolling

topographies, the rise and fall of the land causes drastic inconsistency in the water pressure in the thin tubes. How do you determine the number of Emitters needed for a plant? the soil type and the subsurface wetting pattern that it promotes, the canopy area of the plant, and the percentage of the plant's root zone that is to be wetted. Most plants only require 50% of the root zone to be wetted. Emitters need to avoid direct contact with the trunk or stem of a plant. Irrigation pipes and valves are usually covered ___ with a valve cover? at ground level Circular Pattern heads are defined by:

1. Radius of water flow
2. Arc of water pattern
3. Trajectory of water from the head Static water pressure in any area can be determined by?
4. Calling the water supplier/Utility Company
5. Calling Fire Department
6. Checking it yourself with a proper gauge What is a water window? Amount of time available for irrigation What is a typical water pressure available in a city environment? 65 PSI On top of most valves there is a bleed screw, what is the purpose of the screw? Turns valve on and off How is pipe sized for irrigation? According to how much water can go through it In a static pressure situation, what position is the valve from the mainline in? off When running wire for irrigation in a trench, you should run the wires? Under the pipe in the trench

Increases pressure At what trajectory would your head be for watering under shrubs? 0" The controllers function in an irrigation system is? To schedule the time of day the system turns on and off What type of head is best for watering medians, narrow areas? Rectilinear If using plastic pipe for access to a valve you should place the pipe over the valve from ___ down to the valve? Ground level Spray heads have a precipitation rate ranging from? 1"-2" per hour What size valve box is common in commercial landscaping? 10'-12' What causes turbulence and shock waves in pipe? Water velocity over 5 FPS Low voltage wire for electric valves can be? Buried in the ground When pipe is run at the same elevation this allows the pressure to remain the same. If there is a rise or fall in elevation, what would this do to the pressure? Change 0.433 per foot In a drip irrigation system the maximum variation of pressure between the first emitter and the last emitter should be less than ____ to get a uniform GPH flow? 20% Spray heads have a radius of between? 1' - 16' Which way of watering a shrub is the least expensive and needs the least amount of maintenance? Emitters A spray head will...? Cover a smaller area and distribute a lot of water resulting in high precipitation levels

The terms: friction loss, velocity, surge pressure are considered what? Flow characateristics Specific to a drip system three components would be...? Emitters, micro tubing, pressure regulator AMPS and GPM both refer to? Quantity of flow At what trajectory would you need for windy conditions? 10" What is the best location for the valve box? Groundcover beds What is the last thing installed before the sprinkler head? Riser Most hydraulically actuated valves when in a normal state are considered? Open valves What type of rotary sprinkler head is generally used less frequently? 1/4 Circle When locating the valve on a system, what is good practice? Place near center of circuit to allow equal pressure If the difference in water pressure is more than ____ % from the list sprinkler to the farthest, this will cause problems in watering? 20% When designing an irrigation system, what factors are most important?

1. Similar plants water needs
2. Slope conditions - Sun or shade conditions
3. Soil permeability Good practice when wiring valves is to leave an extra ___ for repairs? 1.5' When you place the main water line so that it intersects near the center of the heads in each irrigation circuit, this is called the? H pattern of piping

Valve When routing pipe for irrigation, you should never place pipe at a right angle to the tree roots because? It may damage or kill the tree Pipe sizes are selected based on a flow velocity rate of? 5 FPS What type of jobs require low voltage irrigation wire to be run in plastic pipe for protection of wire? Federal Government Components of a public water delivery system are:

1. City Main
2. Water Meter
3. Service Line Which fitting has the thread on the outside? Male Adaptor What does an un-balanced loop design do? Shorter run, more GPM The maximum radius a spray head can cover is? 6'-8' Why should you use the loop method or loop pipe with irrigation piping? To reduce friction loss What trajectory would be considered stream spray for ground cover, shrub or turf? 35" Sprinkler valve boxes should be located ____ as not to create a hazard once landscape has been installed? at ground level When laying pipe in symmetrically circuits what can this reduce? Installation cost What kind of valve is best when the valve is located below the lateral lines? Angle When you want to change from a large pipe to a small pipe you should use?

a reducing bushing When a longer than usual electrical run for irrigation systems is requested, most contractors use?

Under normal conditions what is the most common wire size used for low voltage irrigation systems?

Which fitting is used to attach a sprinkler body to a PVC pipe? Male Adaptor Rotary gear drive heads pop up from? 2 1/2' - 4' What type of head is best for curvilinear, rectilinear and square areas? Circular The ___ Valve is generally used when all of the irrigation pipe... that is your main and lateral lines... is placed at the same depth? Globe When installing conduit, what type of sleeve should be used to run the electrical wire a minimum of 18" underground for landscaping? Schedule 40 When determining head placement, the major consideration is? Water distribution as if it was raining When water passed through pipe what is a cause of pressure loss? Roughness inside the pipe When calculating flow of working pressure, what don't do you do?

1. Don't go beyond 75% if maximum safe flow for the meter
2. Don't exceed 10% of the static water pressure
3. Don't go beyond velocities of 5'-6' per second If you have a 100' vertical line from a water service, when it hits the horizontal run, what is the PSI coming out?

At what trajectory would you need for turf or standard angle? 25" - 28"

An angle valve is best used when what occurs? changes in elevation What can cause water hammer? Opening and closing of valve too fast When wire in a low voltage irrigation system is wrapped six to eight times around a 1" piece of PVC this is to? Dissipate power if hit by lightning The type of wire used for irrigation systems is UF, and the control wire is typically what color? Red Dynamic water pressure is what? Moving water through pipes A transformer in the controller of an electric valve reduces 120V to what? 24V Wires for valves buried directly in the ground can attract what? Lightening strikes You have a 20' drop in elevation from the main line with a constant static pressure of 43 PSI, it's a 100' run to the valve, what is the PSI at the valve? 43 PSI + 20 X 0. static pressure at valve = 51.66 PSI A 7' drop in elevation will cause what increase in PSI? 7 X 0.433 = 3.03 PSI If a 1' column of water, 1/2" pipe exerts 0.433 PSI at the bottom, what will 1' of 1 1/2" pipe exert 0.433 PSI To prevent fungus growth, you should water your lawn? Before sunrise (4:30AM - 6:00AM) Why do golf courses usually use hydraulic systems rather than electrical systems? Because of frequency of lightning strikes On a planter 8' in diameter, how many linear feet of curbing is needed to go all the way around the planter?

When the trenches are back filled after pipes are laid and tested if need be, what amount of back fill should be placed before tamped? 4" increments If head placement is not done properly turf problems arise, which would be?

1. Dead patches
2. Uneven color
3. Disease and fertilizer damage What is shutoff head? The maximum head the pump will produce at a zero flow rate What kind of gardens would you use bubbler heads on? Rose What is the single most important aspect of an efficient water conserving irrigation system? Sprinkler head selection and placement When would you need to install a pressure regulating valve? When the system static pressure is above 75 PSI with little elevation change What is a controller? An electric timing device that operates each zone for a predetermined time and frequency What are the basic spacing configurations? Rectangular, triangular and square How would you resolve slope problems to some extent? Setting the heads on the slope at an angle 1/2 way between the vertical and perpendicular to the grade How would you install lateral pipe on a slope to avoid major pressure variations and control erosion? Horizontally What is vapor pressure? The pressure at which water turns to vapor How is operating pressure measured? With flow in the line What do you use to blow out a system?

are connected by pipes or tubes. Irrigation systems are divided into zones because there is usually not enough ____ and available flow to run sprinklers for an entire yard or sports field at once. Pressure Fertigation Is the injection of fertilizers, soil amendments, and other water-soluble products into an irrigation system. Drip irrigation Also known as trickle irrigation, micro irrigation or localized irrigation, is an irrigation method that saves water and fertilizer by allowing water to drip slowly to the roots of plants, either onto the soil surface or directly onto the root zone, through a network of valves, pipes, tubing, and emitters. It is done through narrow tubes that deliver water directly to the base of the plant. Bonnet It acts as a cover on the valve body. It is commonly semi- permanently screwed into the valve body or bolted onto it. During manufacture of the valve, the internal parts are put into the body and then it is attached to hold everything together inside. Circular patterns which make up the largest group of sprinkler heads, are defined by the following characteristics:

1. The radius of water thrown
2. The arc of the water pattern
3. The trajectory of the water as it is thrown from the sprinkler head As the water comes out of the sprinkler head, it travels through space to the ground. The angle at which the water leaves the head is trajectory of spray. Trajectories of spray include?
4. 0 Trajectory - This flat spray can be used for throwing water under low shrubs and on tops of hills.
5. 10 Trajectory - This low-angle spray can be used under windy conditions for shrubs, ground cover bed, and turf.

3. 25-28 Trajectory - This is the standard trajectory that most sprinklers throw for use on turf.
4. 35 Trajectory - This is a stream spray used for watering ground cover, shrubs and turf. If we discover our irrigation heads making some areas quite wet and other are relatively dry, then we are going to encounter turf problems such as:
5. Dead patches
6. Uneven color
7. Fertilizer damage (after spreading fertilizer, many people turn on their irrigation systems to wash the feritlizer into soil so that leaves are not burned by the chemicals)
8. Disease caused by overwatering To get even water distribution we must overlap sprinkler spray patterns because: A single sprinkler can supply enough water to grow green grass for only 2/3 of the radius of water throw. The outer 1/3 of the area covered does not receive enough water to sustain good plant growth. Water Window The amount of time available for irrigation. Precipitation rate refers to the number of inches (millimeters) of water that is placed over a certain area per hour. Precipitation rate in inches per hour = 96.3 X the total gpm in a given area/Total square feet of the area being covered Precipitation rate in millimeters per hour = 60 X the total (heads X L/min) in a given area/Square meters of the area being covered Dividing an irrigation design includes:
9. Areas that share similar plant water needs
10. Soil Permeability rates
11. Sun or shade conditions
12. Slope conditions