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Muting and Unmuting the MASH Alarm

December 22, 2025

A MASH alarm (Motion and Sash Height alarm) is a active feedback monitoring device for fume hoods that sounds an alarm if the sash is left open for a period of time without a user present. This system was developed at MIT to promote energy efficiency and safe laboratory practices.

Each Sashimi is equipped with a MASH alarm that can be toggled on or off. The instructions are muting and unmuting the alarm are below.

Instructions:

  • Press on the sensor’s button one time after the initial setup during normal operation.

  • The LED light will blink:

    • Blue if the MASH alarm has been unmuted, or

    • Yellow if the MASH alarm has been muted

Note: If the sensor is restarted, this setting is saved (ie. If the sensor is muted, it will stay muted after restart).