A Matheson's Oxygen Deficiency Monitor model #8061 was installed inside the Hydra room, the sensor is close to the refilling area and the unit is in the room next to it (upper right corner). It was adjusted at 20.9% as recommended. A pulsating alarm tone sounds if the oxygen level drops below 19.5%
19.5%-21.0% no symptom
14.0%-19.5% Headache, fatigue, faulty judgment
10.0%-14.0% Rise in temperature, difficulty breathing
6.0% -10.0% Convulsions, indistinct consciousness
below 6.0% Coma and heart failure, death in minutes
The unit should be used when work is done in the room, in special while refilling the dewar.
It uses 2 AA rechargable batteries (steady sound means battery low). They last ~75 hours, when fully charged.
Sensor's lifetime: 18-24 months, starting today (July 2003). Accuracy +/- 0.3%