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ChemCentre keeps divers breathing easy

ChemCentre keeps divers breathing easy

Date Published: 19-Aug-16

When underwater, divers need to know that the compressed air they are breathing is safe, so ChemCentre analyses compressed air samples to ensure they meet standards.
ChemCentre laboratory technician Greg Buck said divers’ air is either supplied directly by compressors or from compressed air in cylinders.

“We test the quality of air from compressors and from cylinders for compliance with Australian Standards for operations and selection, use and maintenance of respiratory protective equipment,” he said.

“The air supplied by compressors is tested from samples in diving cylinders submitted by the Department of Defence, the State Water Police, and companies that supply compressors or air cylinders for occupational diving.

“We analyse two types of compressors; high pressure compressors, those that supply air at pressures of 12MPa or more and are used for filling storage or diving cylinders, and low pressure compressors that supply air at pressures of 500kPa or less and are used for direct breathing,” Greg said.

Greg and fellow laboratory technician Annette Kolay are responsible for ChemCentre’s compressed air testing service. Sample numbers have been steadily increasing, with 550 samples submitted for analysis in 2015. Most come from the Royal Australian Navy (RAN).
The normal turnaround time for reporting on RAN samples is three days, with urgent samples turned around in one working day. Last year there were 38 samples requiring urgent analysis.

“Usually samples fail because the compressor’s filters have not been replaced at the correct time,” Annette said. “Urgent analysis is sometimes also required because a ship is due to sail. On occasions RAN ships have been refused to leave dock pending results.

“Breathing air must not contain dangerous amounts of carbon monoxide (CO), carbon dioxide (CO2), moisture, oil and other impurities because these contaminates adversely affect the human body when the partial pressure of the gasses is increased.”

Analysis against the standards is carried out using various methods; direct reading instruments are employed to analyse carbon monoxide, oxygen and moisture; Electrochemical Detectors are used to determine carbon monoxide and oxygen concentrations and moisture is determined using a Dew-Point Hygrometer. Carbon dioxide is tested using a Gas Chromatograph coupled to a-Thermal Conductivity Detector and a Flame Ionisation Detector (GC-TCD/FID) by introducing the sample onto the column via the instruments gas inlet. Oil mist is initially sampled onto a membrane filter before being analysed by Fourier Transform Infra-Red Spectroscopy (FTIR).

For further information regarding compressed air analysis, or to arrange for a sample to be tested, contact Greg Buck directly by email or phone 9422 9931. Alternatively contact ChemCentre on 08 9422 9800 or via email (organic_enquiries@chemcentre.wa.gov.au).

Photo: ChemCentre laboratory technician Annette Kolay is part of the team that tests compressed air samples.

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