AS NZS 3580.2.2:2016 pdf free download

AS NZS 3580.2.2:2016 pdf free download
AS NZS 3580.2.2:2016 pdf free download.Methods for sampling and analysis of ambient air
6.6 Manifold
Manifolds shall be used to distribute the reference test atmosphere to the measuring instrument and to exhaust the excess out of the working environment if it is considered hazardous. The gas lines, mixing chamber and manifold shall be of a size such that no pressure differential greater than 1 kPa relative to atmospheric pressure occurs subsequent to the flow control devices.
6.7 Dilution apparatus
The dilution apparatus shall utilize flow controllers (e.g. mass flow controllers, critical orifices) for regulating the flow of CRM and zero air to generate the desired reference test atmosphere. The flow devices shall be capable of maintaining individual constant gas flows within a manufacturer’s stated specification of ±1% of full scale. The operating range shall be in accordance with manufacturer’s specifications. As a general rule for mass flow controllers, the operating range should be between 10% and 90% of full scale.
Zero air and the CRM shall be completely mixed prior to entry to the analyser.
When conducting linearity checks on analysers employing inherently linear measurement principles (e.g. chemiluminescence), the dilution apparatus shall be capable of generating at least three non-zero reference test concentrations of the determinand spaced approximately equally (e.g. 25%, 50%, 75%) over the measurement range. When conducting linearity checks on analysers employing inherently non-linear measurement principles (e.g. non-dispersive infrared), the dilution apparatus shall be capable of generating at least six non-zero reference test concentrations of the determinand spaced approximately equally (e.g. 15%, 30%, 45%, 60%, 75% and 90%) over the measurement range.
The dilution apparatus shall also be capable of generating a zero reference test atmosphere. All reference test atmospheres shall be generated such that there is excess gas produced which is vented in accordance with Clause 6.6.
NOTE: A calibrated measurement device such as a bubble flow meter, dry gas meter or other flow meter certified to traceable national standards, such as a piston type unit, may be suitable. Bubble flow meter readings need to be corrected for water vapour pressure. The swept volume for a bubble meter is calibrated by weighing the equivalent volume of water displaced.
Temperature and pressure corrections to the reference flow meter indicated rate may be required for certain flow measurement devices (e.g. mass flow controllers), to enable comparison with the flow meter measurement. When temperature and pressure corrections are necessary, the temperature and pressure at the time of calibration shall be used.