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Safety·Lesson 22 of 28

Stored-Energy Surprises: Pneumatics and Springs

The pressurized-system and spring/tubing mistakes that injure hands during pit work, plus the relieve-and-verify fix.

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Mechanical and pneumatic stored energy injures people during routine pit work because it's invisible. A cylinder that fires when you bump a button, or a climber spring that releases when you remove a pin, moves faster than you can pull your hand back.

Pneumatic mistakes:

  • Mistake - Working on a charged system. A robot can hold stored air even when 'off.' Touching a fitting or solenoid can fire a cylinder. Fix: before any pneumatic work, open the manual vent plug (FRC rules require an easily accessible manual vent valve that releases all system pressure without tools) and confirm BOTH the storage and working pressure gauges read 0 psi. Inspectors verify that pressure fully vents.
  • Mistake - Wrong relief valve or regulator setting (R811 / R808). The compressor relief valve must be set to release at 125 psi (R811), and the working-pressure regulator must be set to 60 psi or less (R808), providing all working pressure. Fix: install/verify the relief valve and regulator before inspection.
  • Mistake - Assuming 'off' means 'safe.' It doesn't. Fix: make 'vent to zero' part of your LOTO procedure every time.

Spring and elastic mistakes:

  • Mistake - Removing a pin from a loaded climber or intake. Springs and surgical tubing store energy, and R203 governs unsafe energy-storage devices. Pulling a retaining pin can snap a mechanism shut on a hand. Fix: relieve the spring/tubing first - back off tension, support the mechanism, or use a controlled-release tool. Never put fingers in the path of a loaded element.
  • Mistake - Raised arm with no support. A raised arm or elevator held only by a motor will drop when power is cut. Fix: lower it or block it before working under it (part of dissipating stored energy in LOTO).

Diagnostic habit: before reaching into any subsystem, ask 'what's still holding energy here?' and answer for all three forms - air, springs/elastic, and gravity-held masses. Vent it, relieve it, or block it, then try to move it by hand to verify it's safe. The teams that get hurt are the ones who skip the 'verify zero energy' step because the fix 'will only take a second.'

Key takeaways

  • Vent pneumatics to 0 psi on both gauges (manual vent plug) before touching fittings - 'off' is not 'safe.'
  • Set the relief valve to 125 psi and the working regulator to 60 psi or less (R811); relieve loaded springs/surgical tubing (R203) before removing pins.
  • Block or lower any motor-held raised arm before working under it, then hand-verify zero energy.

Go deeper

Lesson quiz

Required

Answer all 3 questions correctly to complete this lesson.

1.Before working on an FRC robot's pneumatic system, what does the FIRST Safety Manual require you to do?

2.In a legal FRC pneumatic system, what is the maximum stored (high-side) pressure and the maximum working pressure?

3.Besides venting air, what else does the Safety Manual list as a stored-energy hazard to neutralize before servicing a robot?

Answer every question to submit.