valves directional control valves non-return valves flow control valves pressure control valves...
TRANSCRIPT
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 valvesThe 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.
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 levervalve, 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
Check valve Shuttle valve Dual-pressure valve Quick exhaust valve
Non-return valve and its derivatives
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, theair is expelled to atmosphere close to the cylinder via a large orificeopening
Flow control valves
Throttle valve
Flow control valves influence the volumetric flow of the compressed airin 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-actingcylinders :
•Supply air throttling• Exhaust air throttling
Mechanically adjustable one-way flow control valve
Pressure valves
They are divided into the three groups: Pressure regulating valve Pressure sequence valve Pressure limiting valve
Pressure regulating valve
Adjustable pressuresequence valve
Pressure relief valves protect the compressor andcomponents by setting the maximum sys tem pressure within safe working limits.
Pressure relief valves
Pressure limiting valve
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
Time delay valve:normally closed
Time delay valve:normally open
Time response of circuitswith time delay valves
Time response of circuitswith time delay valves
Time response of circuitswith time delay valves
Pulse generator, Stepper modules Memory modules
which incorporate directional controlvalve functions and logic elements
to perform a combined processingtask. This reduces size, cost and
complexity of the system