Globe Valves

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Globe Valves

GCO 2431

Irrigation

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Remote Control Valves


The theory of valve operation is the same

regardless of the manufacturer


• Forward Flow

• Reverse Flow

Two Different Styles of Valves


Identifying A Forward Flow Valve

• When looking into the inlet side, you will see the center

of the diaphragm


Identifying A Reverse Flow Valve

• When looking into the inlet side, you will find a wall of

brass or plastic, the diaphragm is not visible


Major Components


Internal Components


Valve Operation

• Forward flow in the closed position


Why does the valve stay off?

• There is greater force above the diaphragm than below

the diaphragm

• Why is pressure not the correct answer?


Force = Pressure x Surface Area

• The pressure above the diaphragm is the same as

below the diaphragm

• The surface area above the diaphragm is

approximately 1½ times greater than the surface area

below the diaphragm, therefore, there is 1½ times

greater force above the diaphragm keeping the valve

closed


Purpose Of The Spring

• It pushes down on the diaphragm so that it wants to

close.


Opening the Valve

• Release the pressure in the upper chamber

– This reduces the force above the diaphragm

• This can be done automatically or manually


Opening the Valve Automatically

• The controller sends 24 VAC to the solenoid

• The solenoid coil develops a magnetic field which lifts

the plunger

• The upper chamber water exits through the exhaust

port

• The force below the diaphragm is now greater


Opening The Valve Automatically

• Water Escapes From The Upper Chamber


Forward Flow Valve Open


Closing The Valve

• The controller stops sending 24 VAC

• The plunger covers the exhaust port

• Water is trapped in the upper chamber

• The force increases above the diaphragm


Force Increases In The Upper Chamber


Forward Flow Valve Closed


Opening the Valve Manually

• Internal manual bleed

– Turn the solenoid counter-clockwise ¼ turn

– The upper chamber water exits through the exhaust port

– The force below the diaphragm is now greater

– The valve opens


Internal Manual Bleed Operation


Reverse Flow Valve

• How does the water enter the upper chamber?

– External tube

– Internal port

– Directly through the diaphragm


Reverse Flow Valve

• Directly through the diaphragm

– DV series


DV Series Valve


• Internal port

– GB series

Reverse Flow Valve


GB Series Valve


• External tube

– EFB-CP series

Reverse Flow Valve


EFB-CP Series Valve


Closing Speed

• The closing speed is controlled by using a fluid resistor

to regulate how fast water enters the upper chamber

• The solenoid port and exhaust port allow water to

escape faster than it can be replenished into the upper

chamber


Opening the Valve Automatically

• The controller sends 24 VAC to the solenoid

• The solenoid coil develops a magnetic field which lifts

the plunger

• The upper chamber water exits through the exhaust

port

• The force below the diaphragm is now greater


Opening the Valve Automatically

• Water Escapes From The Upper Chamber


Reverse Flow Valve Open


Closing The Valve

• The controller stops sending 24 VAC

• The plunger covers the exhaust port

• Water is trapped in the upper chamber

• The force increases above the diaphragm


Force Increases In The Upper Chamber


The Valve Closes


Opening the Valve Manually

• Internal manual bleed

– Turn the solenoid counter-clockwise ¼ turn

– The upper chamber water exits through the exhaust port

– The force below the diaphragm is now greater

– The valve opens


Internal Manual Bleed Operation


Opening the Valve Manually

• External manual bleed

– Turn the bleed screw counter-clockwise

– The upper chamber water “vents to atmosphere”

» Water escapes faster through the external bleed

– The force below the diaphragm is now greater

– The valve opens


External Manual Bleed Operation


• Check for the obvious

– Is the water turned on?

Troubleshooting

» Manually bleed several valves

– Is the valve receiving 24 VAC?

» Feel the solenoid for heat or vibration

• Defective controller or programming problem


• Valve not closing

– Seeping

• Valve not opening

Troubleshooting


Valve Is Not Closing

• Solenoid plunger stuck in the up position

– Dirt and debris

– Corrosion


Plunger Stuck In The Up Position


• Diaphragm filter plugged

Valve Is Not Closing

– No water can enter the upper chamber


Diaphragm Filter Plugged


Valve Is Not Closing

• Receiving voltage from the controller

– Defective controller

– Incorrect programming


Constant Voltage To The Solenoid


Valve Is Not Closing

• Debris under the diaphragm assembly

– Rocks and other debris


Debris Under The Diaphragm


Valve Is Not Closing

• Large hole in the diaphragm - Forward Flow

– Sufficient force cannot develop in the upper chamber


Large Hole In A Diaphragm - FF Valve


Valve Is Not Closing

• DV valve installed backwards

• The valve operates backwards

– When 24 VAC is applied, the valve closes


• Diaphragm seat damaged

Valve Is Seeping


Diaphragm Seat Damaged


• Solenoid seat damaged

Valve Is Seeping


Solenoid Seat Damaged


Valve Is Seeping

• Small hole in the diaphragm - Forward Flow


Small Hole In The Diaphragm - FF Valve


Valve Is Not Opening

• Valve is installed backwards

– All valve have arrows on them which indicates the

direction of water flow


Valve Is Not Opening

• Flow control tightened too far

– Water will pass through the exhaust port only


Flow Control Stem Too Tight


• Solenoid defective

Valve Is Not Opening

– Check the resistance of the field wires and the coil with a

multimeter

» The solenoid should be between 20 and 60 ohms


Valve Is Not Opening

• Solenoid plunger stuck in the down position

– Dirt and debris

– Corrosion

– Plunger spring installed incorrectly


Plunger Stuck In The Down Position


• Plugged solenoid port

– Small rocks or sand

Valve Is Not Opening


Plugged Solenoid Port


• Plugged exhaust port

– Small rocks or sand

Valve Is Not Opening


Plugged Exhaust Port


Valve Is Not Opening

• Large hole in the diaphragm - Reverse Flow

– Water will pass through the exhaust port only


Large Hole In The Diaphragm - RF Valve


Valve Is Not Opening Fully

• Small hole in the diaphragm - Reverse Flow


Vave Not Opening Fully - RF Valve

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