Phosphine tester is a potent, highly toxic and acutely irritating gas. Chronic exposure to low concentrations of phosphine has been associated with chromosomal damage and can cause low red blood cell counts (anemia), inflammation of the large airways (bronchitis), gastrointestinal disturbances, kidney failure and vision, speech and motor disturbances. Ingestion of phosphine is also associated with a painful jaw disorder called “phossy jaw” and can be fatal if ingested in sufficient quantities.

The current testing method at some grain receival sites requires a spear sample of the grain to be below a Safe Work Australia standard of 0.3 parts per million (ppm) time-weighted average (TWA), i.e. the gas levels in the air that operators breathe over an eight-hour workday and 40-hour week. Further research is needed to compare the phosphine gas concentrations measured within the grain bulk with those measured in the air that operators breathe, and determine if these locations have appropriate TWA exposure standards.

Sensing Combustibles: Understanding the Function of Combustibles Sensors

Previous work has demonstrated the effectiveness of a wireless system that uses 23 permanently installed sampling airlines in metal grain bins to monitor phosphine concentration during a fumigation. However, this system is labor intensive and dependent on worker availability. This study aims to reduce the monitoring frequency by using wireless technology and by comparing the readings of this new system with those of the monitoring lines and a hand-held meter. The sensitivity and accuracy of the sensors and meter were tested in various ambient conditions, and the impact of humidity was studied. The device was found to be capable of testing phosphine canister performance, and the relationship between canister protection times and concentration and flow rate was identified.