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