Control Valves

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Control Valves
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Types of Valves

• Directional Control Valves
• Sliding Spool Valves
• Poppet-Type Valves
• Flow Control Valves
• Pressure Control Valves
• Manual Shut-off Valves

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Spool Principle
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Spool Principle
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Spool Valves

• System pressure does not cause spool to move.
• If more streams are needed, spool is made with
  more than one groove.

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Spool Valve
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Action of the 2 -way
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3-Way Normally Closed
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3-Way Normally Open
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Common Valve Actions
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Poppet Valves
Poppet valves are always unbalanced. Not suited
to high pressure at high flowrate.
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Poppet Valves
Air Pilot Operated
Solenoid Operated
Foot Pedal Poppet
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DC Solenoid
Same current throughout stroke Constant closing
time Quiet operation 6,12,24 Volts are standard
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AC Solenoid
Takes more current when plunger is out of the
coil and can therefore burn up if it sticks. Must
close completely to reduce current to safe
level. Faster than DC but closing time is
variable. Can be noisy (hum) 110, 230 VAC are
standard
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AC Coil Current Heating

• If the armature does not close far enough, the
  reactance of the coil will remain low.
• The low reactance will permit too much current in
  the coil.
• The coil will heat and burn out prematurely.

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Pressure Relief Valves
Equalizes pressure
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Piloted Pressure Relief Valve
If system pressure goes high, needle valve opens
relieving pressure on top of poppet.
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Application of Pressure Relief Valve
Coasting
Driven
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Gate Shut-Off Valves
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Ball Valve
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Needle Valve
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Flow Control Application
Needle Valve
DP only if there is some resistance to piston.
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Four and Five-Way
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Four Way Air Valve
Dual Exhausts
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Direct acting solenoids
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Solenoid Operated Valves
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Pilot Operated Solenoids
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Trio
Filter Pressure Regulator Lubricator