Air Circuitry

1
Air Circuitry

• An Introduction

2
Pressure Control

• Air compressor operates between set point (cut-in
  and cut-out) Typically 110 to 140 PSI
• Set pressure regulator below cut-in pressure
• Place close to actuator for maximum accuracy

3
Where to put the regulator?
4
Processing the Air

• Air directly from compressor must be filtered,
  regulated, and lubricated (always in that order).
• Put a trio on every machine.

5
Power Loss through the regulator.

• Any time air pressure steps down without
  performing useful work, power is lost.
• The power loss is proportional to the pressure
  drop.
• To conserve energy, set the compressor cut off
  pressure only as high as needed to get desired
  force and speed for all actuators in the system.

6
Cylinder Speed and Air Pressure

• Whenever air flows, there will be a pressure drop
  because of air flow resistance.
• Compressor pressure must be high enough to move
  the load and to make up for system losses.
• Cylinder speed depends on how much additional
  pressure is available.

7
No Surplus of Air pressure
Air does not flow, Load does not move.
8
Small surplus of air pressure.
Air flows, Load moves slowly upward.
9
25 (Normal Design)surplus provides good speed
10
Additional load reduces surplus pressure and flow
slows and piston slows.
11
Stall causes 0 pressure surplus. Flow stops,
Piston stops.
12
Cylinder Size vs. Inlet pressure for sufficient
speed.

• Cylinder should provide 25 to 100 more force
  than needed to balance the load.
• This gives enough surplus pressure for sufficient
  speed.
• If the speed is too fast, slow it down with a
  flow control valve.

13
Clamp Circuit

• Open needle valves and set regulator to
  sufficient squeeze force.
• Adjust needle valve 1 for sufficient speed
  without impact.
• Adjust needle valve 2 to limit speed of return
  stroke.

Clamp force on extension.
14
Hydraulic cylinder slows down an air cylinder
and keeps it from bouncing.
At breakaway pressure, load would suddenly and
dangerously accelerate.
15
Multiple Air Cylinders

• Independently acting cylinders must have separate
  control valves.