21 Sprinklers & Components Practice Questions & Answers

1. 1. A spray-head zone was extended by tapping two gear-driven rotors onto the same lateral. After several weeks the turf under the spray heads is soggy while the ground under the rotors stays dry, even though the station run time has been increased twice. What best explains this?

   • A.The rotors pop up more slowly than the sprays, so they lose much of the station's run time.
   • B.The rotors lower zone pressure, which makes the spray heads throw well beyond their spacing.
   • C.The rotors draw enough flow to stall the valve diaphragm, so the station never opens fully.
   • D.The rotors apply water far more slowly than the sprays, so no single run time can satisfy both.✓ Answer

   Rotors and fixed sprays have radically different precipitation rates because a rotor spreads its flow over a much larger area, so it applies depth several times more slowly than a spray. One valve gives both families the same run time, so any time long enough for the rotors floods the spray area. That is why device families are never mixed on one zone.

   Source: Irrigation Association, Landscape Irrigation System Installation & Maintenance — matched precipitation rate and zoning of like devicesReport a problem with this question

2. 2. A technician inspects a rotor zone and finds dry rings between heads: each rotor's stream stops several feet short of the neighbouring head. Which spacing rule should the layout have followed?

   • A.Space heads at about 50% of the diameter of throw so each stream reaches the next head.✓ Answer
   • B.Space heads at the full diameter of throw so that adjacent wetted patterns just touch.
   • C.Space heads at about 75% of the diameter of throw so that patterns barely overlap.
   • D.Space heads by nozzle discharge in gpm rather than by the distance the nozzle throws.

   A sprinkler applies most water near itself and very little at the end of its throw, so single coverage is never uniform. Head-to-head coverage places heads at about half the diameter of throw — that is, spacing equal to the radius — so every point receives water from more than one head and the thin outer edges are filled in by neighbours.

   Source: Irrigation Association, Landscape Irrigation System Installation & Maintenance — head-to-head spacing and distribution uniformityReport a problem with this question

3. 3. On a spray zone the water leaves the nozzles as a fine drifting mist and the outer edge of each pattern falls short of the heads it should reach. A pressure reading taken at the nozzle is well above the pressure the nozzle is rated for. What should the technician do?

   • A.Open the valve's flow control fully so the surplus pressure passes through the heads faster.
   • B.Add run time to the station so the misting area still receives the depth of water it needs.
   • C.Fit nozzles of a longer radius so the extra pressure carries the water across the full spacing.
   • D.Fit pressure-regulating bodies or a regulator so the nozzles run within their rated pressure.✓ Answer

   Above its rated pressure a nozzle atomises the stream: the droplets become so small that they lose energy and drift, so the effective radius actually shrinks while water is lost to wind. Bringing nozzle pressure back into the manufacturer's range with pressure-regulating bodies or an inline regulator restores droplet size, radius and uniformity.

   Source: Irrigation Association, Landscape Irrigation System Installation & Maintenance — operating pressure at the nozzle and pressure regulationReport a problem with this question

4. 4. Rotors on one zone throw only about half their rated radius and one rotor turns slowly and stops part way through its arc. The nozzles are the ones the design calls for and the arcs are set correctly. What is the most likely cause?

   • A.The rotor bodies sit too high on their swing joints for the finished grade of the turf.
   • B.Pressure at the nozzles is below what those rotors need to drive the gear and stream.✓ Answer
   • C.The rotors were spaced far closer than head to head, so their patterns overlap heavily.
   • D.Pressure at the nozzles is above what those rotors need, which shortens every throw.

   A gear-driven rotor takes its rotation energy from the stream itself, so pressure below the manufacturer's requirement produces both a short throw and slow or stalled rotation. Height on the swing joint and spacing change coverage but neither stops a rotor from turning, which points the diagnosis at nozzle pressure.

   Source: Irrigation Association, Landscape Irrigation System Installation & Maintenance — manufacturer pressure requirements for rotorsReport a problem with this question

5. 5. A spray zone mixes full-circle, half-circle and quarter-circle heads, all at the same radius, and the design specifies matched precipitation rate nozzles. What does that requirement mean for the nozzles?

   • A.Nozzle flow is proportional to arc, so a quarter circle discharges about a quarter of a full circle.✓ Answer
   • B.Every nozzle discharges the same flow, so each head delivers equal gallons per minute.
   • C.Nozzle flow depends only on radius, so any nozzle of that radius applies the same depth.
   • D.Nozzle flow is inversely proportional to arc, so a quarter circle discharges four times the flow.

   Matched precipitation rate means each nozzle's discharge is scaled to the area it waters. A quarter-circle head covers a quarter of the area a full circle covers, so it must discharge roughly a quarter of the flow for every head on the zone to apply the same depth per hour.

   Source: Irrigation Association Glossary of Irrigation Terms — matched precipitation rateReport a problem with this question

6. 6. Full-circle spray heads on a square spacing of 15 ft by 15 ft each discharge 3.0 gpm. Using PR = 96.3 x gpm / (S x L), where S and L are the spacings in feet, what is the precipitation rate of the zone?

   • A.0.64 in/hr
   • B.1.93 in/hr
   • C.2.57 in/hr
   • D.1.28 in/hr✓ Answer

   Each full-circle head is responsible for the rectangle formed by its spacings, 15 x 15 = 225 sq ft. Applying the formula, 96.3 x 3.0 / 225 = 1.28 in/hr. The constant 96.3 converts gallons per minute spread over square feet into inches of depth per hour.

   Source: Irrigation Association, Basic Irrigation Hydraulics Student Workbook — precipitation rate formulaReport a problem with this question

7. 7. The same heads and nozzles are laid out on a triangular pattern instead of a square one, with the rows set at 0.866 of the head spacing along each row. Compared with the square layout, what happens to the precipitation rate?

   • A.It rises, because the rows are closer together and each head covers a smaller area.✓ Answer
   • B.It stays the same, because the heads and nozzles discharge exactly the same flow.
   • C.It falls, because triangular rows overlap less and lose part of the applied water.
   • D.It falls, because each head in a triangular layout is responsible for a larger area.

   Precipitation rate is flow divided by the area each head serves. In an equilateral triangular layout the row spacing is 0.866 of the spacing along the row, so the same flow is applied to a smaller area and the rate rises. The 0.866 factor is entered as the row dimension in the precipitation rate formula.

   Source: Irrigation Association, Basic Irrigation Hydraulics Student Workbook — triangular spacing factor in precipitation rateReport a problem with this question

8. 8. A half-circle spray head throws about two feet past the edge of the lawn onto the walk. The nozzle's radius-reduction screw would have to be turned nearly all the way down to stop the overspray. What is the better repair?

   • A.Throttle the valve's flow control, since less zone flow shortens the throw at every head.
   • B.Lower the head on its swing joint, since a nozzle set lower throws a shorter distance.
   • C.Install a nozzle rated for the shorter radius, since heavy throttling ruins the pattern.✓ Answer
   • D.Change the nozzle arc from a half to a quarter, since a narrower arc shortens the throw.

   The radius-reduction screw shortens throw by deflecting and throttling the stream, so heavy use of it produces close-in fine drops, a distorted pattern and poor uniformity. A nozzle made for the shorter radius delivers a proper pattern at that distance, which is why nozzle selection rather than screw adjustment is the fix.

   Source: Irrigation Association, Landscape Irrigation System Installation & Maintenance — nozzle selection and radius adjustmentReport a problem with this question

9. 9. Every time a hillside zone shuts off, the two heads at the bottom of the slope keep running for a minute or two and then stop on their own, leaving a soggy patch. The rest of the zone stops cleanly. What should the technician do?

   • A.Replace the pressure-regulating stems in those heads, since a failed stem stays wide open.
   • B.Close the valve's manual bleed lever, since an open bleed holds the diaphragm off its seat all cycle.
   • C.Install check valves in or below those two heads, since the lateral drains out the low point.✓ Answer
   • D.Replace the zone valve's diaphragm and clean the seat, since the valve is passing water.

   Water left in the lateral after the valve closes runs downhill and escapes through the lowest heads until the pipe empties, which is low-head drainage. Because the flow stops by itself and only the low heads weep, the valve is sealing correctly; check valves in or ahead of those heads hold the column of water in the pipe.

   Source: Irrigation Association, Landscape Irrigation System Installation & Maintenance — low-head drainage and check valvesReport a problem with this question

10. 10. A technician replacing heads in a mowed lawn finds that the previous installer used fixed risers with the nozzles standing a few inches above grade. Why should pop-up bodies be used instead in that turf?

    • A.A pop-up body increases the nozzle's radius while it is up, which a fixed riser cannot match.
    • B.A pop-up body regulates its own inlet pressure, which a riser-mounted head cannot do at all.
    • C.A pop-up body retracts to grade between cycles, keeping the nozzle clear of mowers and feet.✓ Answer
    • D.A pop-up body drains the lateral after every cycle, which a fixed riser cannot do on a slope.

    A pop-up body lifts the nozzle above the grass only while the zone runs and returns flush with grade afterwards, so mowers, foot traffic and vehicles pass over it. A fixed riser standing above grade in turf is a trip and mower hazard and is broken off repeatedly, which is why risers belong in shrub beds.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — pop-up bodies and risersReport a problem with this question

11. 11. A technician is explaining to an apprentice how a normally closed diaphragm zone valve opens when the controller calls that station. Which description is correct?

    • A.The solenoid plunger pulls the diaphragm mechanically off its seat for as long as the station runs.
    • B.The solenoid vents water out of the bonnet chamber, and line pressure below lifts the diaphragm.✓ Answer
    • C.The solenoid admits line pressure into the bonnet chamber, and that pressure pushes the diaphragm up.
    • D.The solenoid turns a small motor that rotates the flow control stem open for the length of the cycle.

    The valve is held shut by water pressure trapped above the diaphragm in the bonnet chamber acting on a larger area than the inlet. Energising the solenoid opens a small bleed path that lets that water escape; the pressure differential reverses and inlet pressure lifts the diaphragm off the seat. De-energising closes the path, the chamber refills and the valve reseats.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — diaphragm valve operationReport a problem with this question

12. 12. The flow control stem on top of an electric zone valve has been turned partway down. What does that adjustment do to the valve?

    • A.It limits how far the diaphragm can lift, throttling the flow the valve passes downstream.✓ Answer
    • B.It trims the current drawn by the solenoid so the coil matches the controller's station rating.
    • C.It sets how long the diaphragm takes to reseat, which controls surge when the valve closes.
    • D.It holds the outlet pressure at a set value no matter how the supply pressure changes upstream.

    The flow control stem is a mechanical stop that reaches down into the valve and limits the travel of the diaphragm. Screwing it down restricts the opening, so less water passes and pressure downstream drops; run fully down it closes the valve by hand for service.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — valve flow controlReport a problem with this question

13. 13. A zone is running continuously. The technician switches the controller off and disconnects that station's field wires at the controller, and the zone keeps running. What is the most likely cause?

    • A.The solenoid coil is shorted and is still being energized by the controller's station output.
    • B.A failed pressure regulator upstream is holding the valve's diaphragm off its seat.
    • C.The valve's manual bleed is open, venting the bonnet so the diaphragm cannot reseat.✓ Answer
    • D.The master valve circuit is stuck on and is driving that station's solenoid directly.

    With the controller off and the field wires disconnected, no electrical path can be holding the valve open, so the fault must be hydraulic or mechanical at the valve. An open manual bleed keeps venting the bonnet chamber, which is exactly what the solenoid does electrically, so the diaphragm stays lifted until the bleed is closed.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — manual bleed and valve troubleshootingReport a problem with this question

14. 14. After a station shuts off, a small stream keeps coming from the heads on that zone and never stops. With the solenoid removed the valve still passes water. What is the most likely cause?

    • A.A short in the field wiring is holding a small current on that station's solenoid coil.
    • B.The lowest heads on the zone have no check valves, so the lateral drains after shutoff.
    • C.Debris on the seat or a damaged diaphragm is keeping the valve from sealing completely.✓ Answer
    • D.Static pressure at the point of connection is higher than the valve's rated working range.

    Removing the solenoid takes the electrical circuit out of the picture, so a valve that still passes water is failing to seal mechanically. Grit trapped on the seat or a torn, warped or swollen diaphragm leaves a gap the water flows through. Low-head drainage is ruled out because that stops once the lateral empties, while this leak never stops.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — valve maintenance and repairReport a problem with this question

15. 15. A commercial system has a valve at the point of connection that the controller energizes whenever any station is running. What is that valve's purpose?

    • A.It keeps the mainline unpressurized between cycles, limiting the loss if a main line breaks.✓ Answer
    • B.It lets a technician isolate one lateral for repair without draining the system.
    • C.It energizes the stations in turn so that only one zone valve can be open at any moment.
    • D.It reduces the pressure delivered to every downstream zone valve to a preset working value.

    That component is a master valve. It opens only while a station is calling, so the mainline downstream of it carries pressure just during irrigation. If the main or a zone valve later fails, the volume that can escape is limited to a running cycle instead of days of constant pressure.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — master valvesReport a problem with this question

16. 16. A large turf area has a fitting set flush in a box on the pressurized mainline; a grounds crew opens it with a special key and hose swivel. What is that component and what is it for?

    • A.A drain valve, which empties the mainline into a gravel sump when the system is winterized.
    • B.A pressure-relief valve, which opens on its own when mainline pressure climbs too high.
    • C.A test port valve, which lets a gauge read mainline pressure while the system stays under pressure.
    • D.A quick-coupling valve, which gives a keyed outlet on the main for hand watering with a hose.✓ Answer

    A quick-coupling valve is a spring-loaded outlet permanently tapped into the pressurized main and normally closed. Inserting and turning the coupler key opens it and gives a hose connection wherever it is placed, so crews can syringe, hand water or wash without running a hose from a distant bib.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — quick-coupling valvesReport a problem with this question

17. 17. A drip zone is being assembled downstream of its zone valve. In what order should the components be installed?

    • A.Filter first, then the lateral, with the pressure regulator at the flush end.
    • B.Filter first, then the pressure regulator, then the dripline lateral.✓ Answer
    • C.Pressure regulator first, then the lateral, with the filter at the flush end.
    • D.Pressure regulator first, then the filter, then the dripline lateral.

    Every drip zone needs both filtration and pressure regulation, and the filter goes upstream of the regulator so grit never reaches the regulator's working parts or the emitters. Filtering after regulation, or at the end of the lateral, leaves the emitters exposed to the particles that plug them.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — drip zone filtration and pressure regulationReport a problem with this question

18. 18. A drip zone has 60 emitters rated at 1.0 gph and 30 emitters rated at 2.0 gph. What is the total flow of that zone in gallons per minute?

    • A.2.0 gpm✓ Answer
    • B.12.0 gpm
    • C.1.5 gpm
    • D.120 gpm

    Emitters are rated in gallons per hour, so the totals must be converted before they can be compared with a system flow in gallons per minute. Here 60 x 1.0 + 30 x 2.0 = 120 gph, and 120 divided by 60 minutes gives 2.0 gpm.

    Source: Irrigation Association, Basic Irrigation Hydraulics Student Workbook — emitter flow rates and unit conversionReport a problem with this question

19. 19. A dripline zone that has run for two seasons is being serviced. Which procedure clears sediment that has settled in the tubing before it plugs the emitters?

    • A.Open the flush end of each lateral and run the zone until the water discharging runs clear.✓ Answer
    • B.Take the filter element out and run the zone so the trapped sediment washes down the laterals.
    • C.Raise the regulator's setting for a few minutes so higher pressure drives debris out of the emitters.
    • D.Cap the far end of each lateral and run the zone so pressure forces particles out the emitters.

    Emitter outlets are far too small to pass the silt and biological growth that settle in a lateral, so debris has to leave through an opening larger than an emitter. Opening the flush end sends a high velocity slug of water down the tube and out the end, carrying the sediment with it; the end is closed again once the discharge runs clear.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — drip system maintenance and flushingReport a problem with this question

20. 20. A subsurface dripline zone is installed in a lawn that has a noticeable high point. The specification calls for an air/vacuum relief valve at that high point. What does that device do for the zone?

    • A.It holds water in the laterals after shutoff so the zone reaches full output more quickly.
    • B.It admits air as the lines drain so suction cannot pull soil and grit back into the emitters.✓ Answer
    • C.It relieves pressure as the zone fills so the dripline is not over-pressured at startup.
    • D.It bleeds trapped air out during operation so the emitters at the high point discharge more.

    When a buried zone shuts off, water draining to the low points leaves a partial vacuum behind it at the high point, and buried emitters will then suck in soil, silt and roots that permanently plug them. An air/vacuum relief valve at the high point breaks that vacuum by letting air in, and it also lets air escape as the zone fills.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — subsurface drip air/vacuum reliefReport a problem with this question

21. 21. A system with a flow sensor and a master valve shuts down mid-cycle and reports flow far above the value learned for the station that was running. What condition does that reading point to?

    • A.Worn nozzles on that zone are applying water more slowly than the design intended for it.
    • B.A clogged filter ahead of the zone is restricting the water reaching the running station.
    • C.A partly closed isolation valve upstream is throttling the supply feeding the running zone.
    • D.A broken lateral or a missing head on that zone is passing more water than designed.✓ Answer

    A flow sensor compares measured flow with the normal flow learned for each station, and only an unintended opening downstream makes the number go up. A broken lateral, a sheared head or a blown fitting passes far more water than the nozzles alone, so the controller closes the master valve to limit the loss. Restrictions such as a closed valve or a plugged filter show up as low flow instead.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — flow sensors and master valve shutdownReport a problem with this question

Practice questions based on the Irrigation Association's published Certified Irrigation Technician content — basic irrigation principles, basic electrical principles and basic hydraulics — together with standard irrigation installation, hydraulics and backflow-prevention references. This site is not affiliated with or endorsed by the Irrigation Association. Irrigation work is governed by local plumbing and irrigation codes, water-purveyor rules and licensing that vary by jurisdiction; backflow assemblies in particular must be selected, installed and tested to the rules in force where you work. Confirm current exam requirements with the Irrigation Association before testing. About IA certification →