Color system on airlock doors: How signal colors protect cleanroom safety

Why airlock doors in the cleanroom must never be open at the same time

The most important principle in any regular operation of a cleanroom system is that both airlock doors must never be open at the same time.
Because as soon as outside air flows into the cleanroom, the risk of particle contamination and pressure drops increases.

To prevent this from happening, cleanroom doors in airlocks are technically interlocked:

• Only when one door is fully closed can the other be unlocked.
• In this way, the separation between the cleanroom and the environment is guaranteed at all times.

Traffic light system on cleanroom doors: green, yellow, red, blue for safety

To ensure that employees and external visitors immediately understand which door they are allowed to use and when, our door control systems for cleanroom airlocks use a color signal system:

• 🟢 Green = Entry permitted → The door can be opened.
• 🟡 Yellow = door is currently open → the door lights up yellow for the short time it is open.
• Red = Blocked → The other door is currently open, access not possible.
  The red signal also lights up if the emergency stop button has been pressed or if a door has been open for too long.
• 🔵 Blue = airlock in purge → Wait briefly. Both doors are locked at the same time while the air is automatically filtered.

The blue signal in particular is crucial for cleanroom safety: during this phase, the airlock is flushed, particles are removed and the air quality is stabilized. After a few seconds, the display switches back to green – and access is granted.

Conclusion: Cleanroom doors with color system increase safety and efficiency

The color system on interlock doors makes complex technology easy for people to understand.
The combination of door interlock, traffic light signals and interlock flushing reliably prevents cleanroom doors from being opened simultaneously and uncontrolled air from entering the cleanroom. Safety is guaranteed at all times – the interlock control system can be overridden by activating the emergency stop for rescue and escape purposes

This makes cleanroom safety recognizable at a glance – even for new employees or external visitors. The result: no double-opened doors, no uncontrolled air exchange – maximum cleanliness.