Transcript pneumatic valves

Valves
Directional control valves
Non-return valves
Flow control valves
Pressure control valves
Shut-off valves
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.
Directional control valves
The valve is described by:
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Number of ports or openings (ways): 2-way, 3-way,
4-way, etc.
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Number of positions: 2 positions, 3 positions, etc.
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Methods of actuation of the valve: manually
actuated, mechanically actuated, pneumatically
actuated, electrically actuated.
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Methods of return actuation: Spring return, air
return, etc.
Directional control valves:
symbol development
numbering system used to designate directional control
valves
Actuation of valves
Actuation of valves
3/2-way valve,normally
closed,ball seat
3/2-way valve:
disc seat normally closed,
3/2-way valve:
disc seat normally open,
3/2-way valve single pilot, normally
closed, with spring return,
Pilot valve:
left unactuated, right actuated
3/2-way roller lever
valve, internal pilot,
Normally closed
Normally open
4/2-way valve,
disc seat,
unactuated
actuated
4/3-way plate slide valve,
mid-position closed
5/2-way valve:
longitudinal slide principle
5/2-way double pilot valve,
suspended disc seat,
flow from 1 to 2
flow from 1 to 4
5/3-way valve, neutral
position variations
Non-return valve and its derivatives
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Check valve
Shuttle valve
Dual-pressure valve
Quick exhaust valve
Non-return valve
Dual pressure valve:
logic AND function
Shuttle valve:
logic OR function
Quick exhaust valve:
flow 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
Flow control valves
Throttle valve
Flow control valves
influence the volumetric
flow of the compressed
air
in both directions
•normally adjustable
•used for speed control
of cylinders
One-way flow control valve
•air flow is throttled in one direction only
•A check valve blocks the flow of air in
the bypass
Fundamentally,
there are two types
of throttling circuits
for double-acting
cylinders:
•Supply air
throttling
• Exhaust air
throttling
Mechanically adjustable oneway flow control valve
Pressure valves
They are divided into the three groups:
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Pressure regulating valve
Pressure sequence valve
Pressure limiting valve
Pressure regulating valve
Adjustable pressure
sequence valve
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.
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:.
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Time delay valves: for the delay of signals
Two-hand start unit
Pulse generator
Stepper modules
Memory modules
Time delay valve:
normally closed
Time delay valve:
normally open
Time response of circuits
with time delay valves
Time response of circuits
with time delay valves
Time response of circuits
with time delay valves
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