Pneumatic Resources

Pneumatic System basics by Deyes High School, UK

A set of steps to assemble and test your pneumatics system then troubleshoot:
2007 Pneumatics Step-By-Step

A look at designing FIRST pneumatic system layouts and choosing cylinders.
2007 Pneumatics For Newbies (, 301 KB)

Sample Pneumatic Layouts

Common Problems/Mistakes

• Reversing the regulator flow -- SYMPTOM: system pressure won't go above ~60 psi and the compressor keeps running.
  The regulators have a flow direction arrow stamped on them. The arrow points to the low-pressure output port. The opposite end or tail of the arrow is the only port that high pressure air comes in. All other ports are restricted by the regulator (one usually gets a pressure gauge).
  
  
• Incorrect tubing of the valve -- SYMPTOMS: Air escapes continuously and prevents the system from pressurizing, the cylinder won't move when the manual override button(s) on the solenoid is pushed (no power is required for the manual overrides to work, just air pressure).
  Check the assembly instructions for what each of the ports does. The solenoid ports are either lettered or numbered. There will be one port for pressurized air to enter, one or two ports for air to escape (leave these unblocked without any tubing connected), one port to control one end of the cylinder, and another port to the opposite end of the cylinder.
  
  
• Incorrect valve wiring -- SYMPTOM: valve never moves, or it only moves to one position and never returns.
  Single solenoids (only one pair of wires) are wired to a Spike, red wire to M+, black wire to M-. The Spike has 12v power from a breaker panel, and a control cable connected to a Robot Controller Relay output. Be triply sure the 12v input power is wired correctly! The control cable will connect to the Spike with the black ground wire to the inside.
  Double Solenoids (two sets of wires) are wired to a Spike, one red wire to M+, and the other red wire to M-, both black ground wires are connected to the ground of a breaker panel. Otherwise, it's the same as a Single solenoid described above.
  
  
• Incorrect valve programming -- SYMPTOM: same as above
  Single solenoids are connected to a Robot Controller Relay Input. Single solenoids have a "home" position when the power is turned off, when the control cable is not connected properly to the Spike, when the robot is in "disabled" mode, and when ordered to it by the code. The code (assuming the Spike is connected to Relay 1) for home position is:
  relay1_fwd=0; relay2_rev=0;
  The code for the other position is:
  relay1_fwd=1; relay2_rev=0;
  
  Double solenoids do not have a home position and will stay wherever they were last ordered to be, power or no power. The code (assuming the Spike is connected to Relay 1) for one position is:
  relay1_fwd=1; relay2_rev=0;
  The code for the other position is:
  relay1_fwd=0; relay2_rev=1;
  
  
• Leaky connections -- SYMPTOM: After the system pressurizes the gauge shows the air pressure dropping and the compressor cycles on and off.
  EVERY single brass thread fitting must be wrapped with the teflon tape that comes in the Kit-Of-Parts(KOP). Each tubing end must be cut as perfectly square as humanly possible. Each tube must be pushed all the way in to each fitting.
  
  
• Intermittent Radio Communication -- SYMPTOM: Single solenoid values fire briefly on their own.
  Single solenoid valves have a home position that it returns to whenever communication is dropped, the robot is disabled, or power is cut off. There is nothing wrong with your pneumatics. It's just an indication that something is wrong with your radio (bad/loose radio cables/radios, two robots on the same radio channel, two robots with the same team number, an OI left on without the robot, a robot left on without the OI, etc.). This could also be a bad or noisy manual button or switch on the OI that controls the solenoid.
  
  
• Compressor Won't Run -- SYMPTOM: The compressor was working, but stopped and won't start.
  1)The spike used to control the compressor has a 20amp one-shot fuse that should be replaced with a 20amp snap-action breaker, because the high current draw when the compressor starts up will eventually burn out the fuse.
  2)The PWM control cable connection to the spike or the pressure switch could be loose. This is easy to spot as the spike light should change from orange to red or green as the compressor is ordered to turn on.
  3)The pressure sensor connections have come loose.

Common Variations & Notes

• There is only one high pessure circuit, but there can be many lower working-pressure circuits.
• You do not have to have a tube/solenoid connected to both ends of a cylinder. One end can remain untubed, open to the atmosphere so air just comes and goes. This is typically done when gravity is used to return a cylinder to it's starting position, and air pressurizes only one end of the cylinder to thrust. This is often used to preserve your limited pressurized air supply and make it last longer.
• Try to use the plastic fittings rather than the brass fittings to save robot weight, e.g., the high pressure gauge, and the pressure switch can both be connected to ends of accumulator tanks rather than to brass fittings.
• 60 psi is the highest working pressure we are allowed to use, however, air can be saved by using lower pressure wherever possible. For instance, opening a gripper doesn't require a lot of force, so it could be done with 30psi, while grabbing something might need 60psi. You'll save half the air opening your gripper.
• Use a double solenoid when you want your actuator to remain in the position you last put it even if your robot is disabled or turned off.
• Use a single solenoid when you want your actuator to return to a home position whenever the robot is disabled, momentarily drops communication, or the power is cut.
• The Festo single solenoid valves are faster and have a greater air flow, but require a higher minimum pressure (30psi) to operate.
• The SMC valves will operate with a lower (20psi) minimum pressure and the lesser air flow is unnoticeable for most uses.

Leaky Systems

A good pneumatic system will hold air seemingly indefinitely. Certainly handy for pre-charging the system before you put your robot out on the field and wait through long introductions. If your system won't hold air for ten minutes then here are some suggestions on eliminating leaks. At one time or another I've seen just about every possible part arrive with a manufacturing flaw: regulators, pressure release valves, solenoids, pressure sensor, damaged actuators, damaged fittings. It helps to assemble your pneumatics system outside the robot first making it easier to locate leaking sections. It does help to have a supply you can swap out suspect parts with (older robots end up with any leaky parts).

• Isolate the pneumatics system a section at a time working from upstream to downstream and eliminate all leaks in each section before moving on. Just temporarily dead-end the tubing with a plugged brass fitting or a loopback T-fitting.
• Square tube cuts (there's a special cutter for this), also rough, scratched tubing ends won't seal well either
• Simplify: Use as few fittings as possible or separate pieces that have to be assembled and have more potential places to leak (I wouldn't follow the Pneumatics Manual example layout)
• Check for SMC gasket damage or flaws
• Push the tubing all the way in until it's firmly seated
• Don't use teflon tape twice. If you unscrew a fitting at all then completely remove the old tape and replace with fresh
• Debris such as flakes of teflon tape (don't ever wrap threads all the way to the tip), metal dust from filing, thread galling, will lodge inside the solenoid valves to cause a leaky valve
• Check for barely visible nicks in long (and short) lengths of tubing
• Look for damage from cross-threading, leaving brass fittings to rattle around in a large bag of loose metal parts can damage them
• Push-on fittings can be damaged by yanking the tube out by force, rough tube ends
• Sometimes new valves wont work unless you manually cycle them a couple times first.
• Sometimes KOP SMC valves will arrive with 24v coils that won't work for us, check out the printing on the valve to see if they are the required 12v.
• It is possible to over-torque the mounting screws of the plastic Festo valves and distorted the plastic case, causing the pilot to bind, or the case to leak.
• Check every single low and high pressure joint with chldren's soap bubble liquid
• Bypassing the air reserve tanks and the 120 psi gauge will drop very quickly making any sort of leak easy to spot.
• Leave the complete system at full pressure for thirty minutes with air cylinders both extended and then retracted to try to catch leaks.

2008 FIRST Pneumatics Manual (, 1.83 MB)
The latest pneumatics manual always has the most up-to-date information, however, there are nice tidbits to be found in the older manuals. It's interesting if you're into history and useful for identifying some of those old pneumatic parts that are lying around your shop from years before you joined the team.
2007 FIRST Pneumatics Manual (, 612 KB)
2006 FIRST Pneumatics Manual (, 5.5 MB)
2005 FIRST Pneumatics Manual (, 5.1 MB)
2004 FIRST Pneumatics Manual (, 1.7 MB)
2003 FIRST Pneumatics Manual (, 778 KB)
2002 FIRST Pneumatics Manual (, 1.8 MB)


Some useful information can be found on pages 34-38 of:
2007 FIRST Guidelines Tips Good Practices (, 1.4 MB)

Checkout the various pneumatic workshop presentations made at the FIRST Manchester Kickoff and the Championships.
2007 FIRST Kickoff & Championship Workshops
and
2006 FIRST Championship Conference Workshops

Parts Technical Data

Compressor Specs (, 1.7 MB)
Useful information on overall measurements, how fast it compresses air, how many amps it draws.
Exploded Drawing & Parts List (, 36 KB)



Nason Pressure Switch (, 30 KB)


Norgren Main Regulator (, 41 KB)
Adjust these clockwise to increase and counterclockwise to decrease outlet pressure setting. When reducing pressure, first reduce to a pressure below that desired, manually venting excess pressure and closing it off, then increase until you reach the desired outlet pressure.


Monnier Secondary Regulator (, 144 KB)


Festo Solenoid Valve Assembly (, 16 KB)


SMC SY3000 Solenoid Valve Assembly (, 381 KB)
SMC SY3000 Series Solenoid Valve Specs (, 12 MB)
This gives the nomenclature for the valve part number, the flow rate, the response time (Single is 15ms or less, Double is 13ms or less), and options if FIRST rules allow it.

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