CLT Preparation Workshops

1
CLT Preparation Workshops

• Irrigation Valve Repair

2
Learning Objectives

• Upon completion of this class, you will be able
  to
  
• Describe the common elements of irrigation
  controls systems.
  
• Explain how solenoid valves operate.
• Troubleshoot solenoid valves.
• Repair and re-assemble solenoid valves.
• Check the system for electrical faults.

3
Additional Information

• Troubleshooting Irrigation Control Systems
  (booklet) by Bill Derryberry
  
• CCC Irrigation Design Course
• ALCA Irrigation Training Manual

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Irrigation Electrical System Elements

• Controller
• Wires
• Valves

5
Typical Irrigation Electrical System
Single controller, single transformer
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Irrigation Electrical System
Cut-Away View of a Solenoid Valve in the CLOSED
Position
7
Irrigation Electrical System
Cut-Away View of the Solenoid Valve in the OPEN
Position
8
Irrigation Electrical System
Water gets into the upper chamber of the valve
byporting.
Ways that the water ports depends on the
manufacturer.
9
Operating Valves Manually

• Manual bleeding is opening the valve manually
  without energizing the solenoid.
  
• Manual bleed mechanism
• External bleed
• bleed screw
• manual bleed lever
• Internal bleed

10
Diagnosing a Valve That Does Not Open

• Is the mainline pressurized? Check the meter,
  main shut off valve and the backflow device
  valves.
  
• Is the flow control handle turned down? Open
  the flow control handle.
  
• Does the valve open and close manually? Open
  and close the manual bleed.
  
• Does that station on the controller have a 24
  volt output? Turn on the station and check with
  voltmeter.
  
• Do you get 24 volts at the valve solenoid wires?
  Check with voltmeter.
  
• Make sure the power is off before taking ohm
  readings.
  
• What is the ohm reading of the solenoid?
• What is the ohm reading of the field wires?

11
Diagnosing a Valve That Does Not Close

• Is the manual bleed mechanism open? Make sure
  bleed mechanism is in the off position.
  
• Does the controller put out a constant 24 volts?
  Check the voltage at the controller.
  
• Will the valve close when you turn down the flow
  control? (If the valve has flow control.)
  
• Is the porting mechanism clogged? Disassemble
  the valve and check it.
  
• Does the diaphragm have a crack or hole
  (unintentional) in it?
  
• Be sure to tighten bolts in a cross sequence when
  you reassemble the valve (twice around).

12
Checklist for Solenoid Valve Disassembly/Assembly

• Turn off mainline or isolation valve. Manually
  bleed the valve.
  
• Carefully remove solenoid assembly and store in a
  safe, dry location.
  
• Slowly loosen valve bonnet bolts/screws in cross
  pattern and let water escape.
  
• Remove bonnet and put internal parts (diaphragm
  assy., spring etc.) and store in a safe, dry
  location.
  
• Clean and inspect the parts and replace defective
  parts.
  
• Bail out any excess water from the valve box and
  clean the valve body.
  
• Reassemble valve with new and/or clean parts. Be
  sure to get proper alignment of the diaphragm.
  Finger tighten bolts/screws in cross pattern.
  Tighten bolts/screws to manufacturers specs in
  cross pattern.

13
Checklist for Electrical Work On Controllers,
Valves, and Wires

• Always make sure the power to the controller is
  OFF when doing electrical work, unless you are
  checking voltage with a voltmeter. Make sure
  the power is OFF when you are checking for
  resistance with an ohmmeter.
• Never touch wires to a hot terminal to identify
  them. Use an ohmmeter or checkmate to identify
  wires.
  
• Always secure wire splices that are made in the
  ground and at the valve with a waterproof
  connecting device.
  
• Coil approximately 24 of the field wires at the
  valve box and at every 90 degree bend in the
  wire path.
  
• Never send current to a solenoid where the
  plunger has been removed. As a precaution,
  always tape the plunger into the solenoid
  after removal.
• When using a multimeter, always set the range
  selector to one level higher than the
  anticipated reading.
  
• Make sure the controller is UL-approved and
  adequately grounded.

14
Basic Electronic Instrument Readings
Multi-meters measure power (volts) and resistance
(ohms). Checking voltage. Primary Secondary O
hm readings Faults open circuits, shorts and p
artials
15
Waterproof Connection Devices
DBY
Scotchlock
Pintite
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What have you learned today?

• Before you leave today
• Complete the post-class test to help us determine
  how effective the class has been.
  
• Fill out the evaluation form.
• Thank you and good luck on the CLT test!