Valves

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Valves

• Directional control valves
• Non-return valves
• Flow control valves
• Pressure control valves
• Shut-off valves

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Directional control valves

• Directional control valves are devices which
  influence the path taken by an air stream.
  Normally this involves one or all of the
  following opening the passage of air and
  directing it to particular air lines, cancelling
  air signals as required by blocking their passage
  and/or relieving the air to atmosphere via an
  exhaust port.

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Directional control valves

• The valve is described by
• Number of ports or openings (ways) 2-way,
  3-way, 4-way, etc.
• Number of positions 2 positions, 3 positions,
  etc.
• Methods of actuation of the valve manually
  actuated, mechanically actuated, pneumatically
  actuated, electrically actuated.
• Methods of return actuation Spring return, air
  return, etc.

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Directional control valvessymbol development
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(No Transcript)
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numbering system used to designate directional
control valves
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Actuation of valves
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Actuation of valves
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3/2-way valve,normally closed,ball seat
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3/2-way valvedisc seat normally closed,
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3/2-way valvedisc seat normally open,
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3/2-way valve single pilot, normally closed, with
spring return,
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Pilot valveleft unactuated, right actuated
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3/2-way roller levervalve, internal pilot,
Normally closed
Normally open
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4/2-way valve,disc seat,
unactuated
actuated
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4/3-way plate slide valve,mid-position closed
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5/2-way valvelongitudinal slide principle
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5/2-way double pilot valve,suspended disc seat,
flow from 1 to 2
flow from 1 to 4
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5/3-way valve, neutral position variations
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Non-return valve and its derivatives

• Check valve
• Shuttle valve
• Dual-pressure valve
• Quick exhaust valve

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Non-return valve
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Dual pressure valvelogic AND function
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Shuttle valvelogic OR function
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Quick exhaust valveflow from 1 to 2
Quick-exhaust valves are used to increase the
piston speed of cylinders by reducing the
resistance to flow, the air is expelled to
atmosphere close to the cylinder via a large
orifice opening
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Flow control valves
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Throttle valve

• Flow control valves influence the volumetric flow
  of the compressed air
• in both directions
• normally adjustable
• used for speed control of cylinders

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One-way flow control valve

• air flow is throttled in one direction only
• A check valve blocks the flow of air in the bypass

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• Fundamentally, there are two types of throttling
  circuits for double-acting
• cylinders
• Supply air throttling
• Exhaust air throttling

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Mechanically adjustable one-way flow control valve
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Pressure valves

• They are divided into the three groups
• Pressure regulating valve
• Pressure sequence valve
• Pressure limiting valve

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Pressure regulating valve
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Adjustable pressuresequence valve
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Pressure relief valves Pressure limiting valve
Pressure relief valves protect the compressor
and components by setting the maximum sys tem
pressure within safe working limits.
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Combinational valves

• Components of different control groups can be
  combined into the body of one unit with the
  features, characteristics and construction of a
  combination of valves, such as.
• Time delay valves for the delay of signals
• Two-hand start unit
• Pulse generator
• Stepper modules
• Memory modules

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Time delay valvenormally closed
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Time delay valvenormally open
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Time response of circuits with time delay valves
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Time response of circuitswith time delay valves
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Time response of circuitswith time delay valves
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Pulse generator, Stepper modules Memory modules

• which incorporate directional control
• valve functions and logic elements to perform a
  combined processing
• task.
• This reduces size, cost and complexity of the
  system