Cleanroom door interlock systems are typically used to prevent both doors of an airlock from being opened at same time. This is to prevent particulates from directly entering the cleanroom from outside the cleanroom.
Door interlock system components:
- Door open sensor (2)
- Door magnetic lock (2)
- PLC control
- Emergency release button
Optional features include:
- LED signs that light up when a door is open.
- Buzzer that goes off when a door is open.
- Timer that delays second door opening (to give airlock time to flush particles).
- Connection to room pressure sensor (To ensure hazardous USP800 room is at negative pressure) before allowing door to open.
The emergency release button is for use when somebody is trapped in airlock and must exit for safety reasons. It overrides the interlock system to allow the second door to be opened even if the first door is not closed.
Door interlocks can be put in rooms with more than two doors. However, design and operation of the interlock system can be complex and requires clear training of personnel in usage.
Material pass thru’s also use door interlocks. Smaller size material pass thru’s use can use mechanical interlocks to ensure that only one door is open at a time. Larger pass thru’s use electrical interlocks.
Air showers use electronic door interlocks with timers to ensure the personnel stay in the shower for the full cleaning cycle.
Door interlocks are often used for laser cleanrooms. They have LED display that warns personnel outside the cleanroom that lasers are operating. Typically, if the personnel open the door the interlock system automatically turns off power to the laser(s) .
Cleanroom door interlocks are most common in more critical applications like pharmaceutical manufacturing cleanrooms, air showers, and medical device cleanrooms.
Summary: Cleanroom door interlocks prevent both doors in airlock/gown room from being opened at same time. This prevents particulates from directly entering the cleanroom from outside the cleanroom. Most interlock systems are electronic. Most common usage are pharmaceutical cleanrooms, medical device cleanrooms and air showers.