Evidence shall show that knowledge has been acquired of safe working practices and designing gas detection systems. All knowledge and skills detailed in this unit should be contextualised to current industry practices and technologies. KS01-EM079A Gas detection systems Evidence shall show an understanding of gas detection systems to an extent indicated by the following aspects: T1 Maintenance procedures in hazardous areas that will ensure the integrity of the explosion-protection technique encompassing: the purpose of a maintenance schedule; the purpose and extent of ‘close’, ‘sample’ and ‘periodic’ inspections; the features of each explosion-protection techniques that should be included in a maintenance schedule; the impact of environmental conditions on explosion-protected equipment, including corrosion and frequency of maintenance; the documentation requirements for recording the maintenance process and results; the use of Standards in determining the requirements with which the design of explosion-protected apparatus shall comply. T2 Techniques for the installation and maintenance of fixed gas detection equipment encompassing: Use of manufacturer’s instruction manual; for example, operating instructions, adjustments procedures and operational limitations. Installation and maintenance of Standards and/or Codes of Practice for gas detection equipment. T3 Location of fixed sample points or sensors encompassing: optimal sensing; maintainability and ease of calibration; and protection against environmental and mechanical damage. T4 Gas and vapour releases encompassing— the nature of a site; and natural and mechanical ventilation. T5 Common problems with fixed gas detectors. T6 Calibration and response checking. T7 Factors to consider in the evaluation and selection of portable and fixed gas detection equipment encompassing: Requirements for gas detection for a given situation: sources for obtaining data on physical chemistry of the gas to be detected; and sources for obtaining data on the conditions under which the gas may be present. processes of assessing the specifications of gas detection equipment against established requirements. T8 Detecting gases and vapours encompassing: apparatus capability and users’ knowledge; propagation of gases - This includes release of gas and vapours, ventilation, density, temperature and location. gases to be detected and not to be detected; intended application; environmental effects; safety when monitoring for flammable gases where personnel could be present; common properties of gases and vapours - This includes density of gases, vapours and their mixtures; effect of temperature on density; LEL and UEL of combustibles and toxicity. the differences between detecting gases and vapours - These include added complication of evaporation, condensation and temperature effects of vapours and their effect on propagation, calibration and detection, including sampling. T9 Oxygen deficiency and effects on safety encompassing: chemical reaction of oxygen with solid products; chemical reaction of oxygen with gaseous products; and dilution of the air by displacement by some other gas or vapour. T10 Measuring principles of catalytic sensors, electrochemical sensors, infrared sensors and semi-conductor sensors encompassing: common applications; limitations and safety; interferences of other gases with the measurement; and poisoning of the sensor. NOTE: Detailed information on gas detection is given in AS/NZS 60079.29.2. T11 Measuring principles of thermal conductivity sensors, flame ionization, detectors (FID), flame temperature analyzers (FTA), photo ionisation detectors (PID) and paramagnetic oxygen detectors. T12 Selection of apparatus encompassing: environment; system response delay; and gas to be detected with respect to measurement principles. T13 Behaviour of gas and vapour releases encompassing: rate of release; density; and temperature/pressure. T14 Design and installation encompassing: sensor, sampling or open path; location; site; and environmental conditions. NOTE: These include adverse weather, excess temperature, vibration and other mechanical interference, hosing, airborne contaminants and corrosion. T15 Integrity and safety encompassing: redundancy; and protection against loss of power supply. T16 Commissioning and scheduled maintenance encompassing: sample lines; diffusion sensor screens; initial gas calibration; adjustment of alarm set points; and plans and records. |