The ICA 221 is an oxygen indicator and alarm to monitor the oxygen in the atmosphere surrounding the instrument. It is designed to protect both product and personnel from low ambient oxygen caused by leakage from storage and production plant for nitrogen, carbon dioxide or other asphyxiant gases.

The ambient atmosphere diffuses into the oxygen sensor which is mounted on the front of the instrument. The output is measured and displayed on the digital controller and the alarm level is set with the control buttons. The alarm will activate below the setpoint which is typically 19% O2.

The alarm consists of an internal low intensity audio sounder and a contact that can be used to switch an external alarm system.

The high-performance electrochemical oxygen sensor is very stable in operation with an expected life of two years. The calibration will gradually decline during the sensor life and recalibrating with fresh air at 21% will occasionally be required.

This sensor, like most gas sensors, measures the partial pressure of the oxygen and therefore the reading will vary in proportion to the barometric pressure. The ICA221 will operate continuously and is powered from the mains AC supply.