Back Diffusion Assembly

Oxygen Sensor Protection During Loss of Flow

The Back Diffusion Assembly protects the oxygen sensor in the analyzer from oxygen exposure through the vent line during a loss of flow condition. When there is no gas flow through your AMI oxygen analyzer, the sensor can be exposed to air entering through the analyzer exhaust line. As air is 20.9% oxygen, the oxygen sensor usable life can be depleted quickly with this continuous exposure to oxygen via backflow through the exhaust line.

Power loss or treatment equipment upsets can result in flow being shutoff to the analyzer. With a Back Diffusion Assembly installed on the vent line, the liquid in the BACK DIFFUSION ASSEMBLY prevents oxygen in air from reaching the sensor through the vent line when gas flow is lost. Glycol is the recommended liquid to use in the Back Diffusion Assembly due to its low freezing point. During normal gas flow operation, the Back Diffusion Assembly has negligible back pressure on the vent line and does not impact the analyzer performance.