Ambient Air quality Monitoring Guidlines. - Maharashtra Pollution ...

(vi) Lack of Dedicated Manpower
If due to shortage of manpower, personnel involved in ambient air quality monitoring are
also involved in other activities and the monitoring data is not generated for adequate
number of days, then the annual average computed may not represent the true annual
average.
(vii) Non-availability of Continuous Power Supply
If due to non-availability of continuous power supply, monitoring is not carried out for 24
hours in a day, then the daily average computed may not represent true daily average.
5.3 Suggestions for Improvement
The following suggestions are made to improve the quality of data
(i) Calibration of Equipments
Calibration of blower, rotameter and time totaliser must be carried out regularly
depending upon use. Calibrated balance and spectrophotometer must be used in the
laboratory. Facilities for calibration must be developed at recognised laboratories such
as zonal offices of CPCB and SPCBs maybe asked to get their instruments calibrated at
these laboratories. The calibration and auditing equipments are described below:
(a) Calibration and Auditing Equipment
Primary Flow Rate Standard - A positive volume displacement device serves as a
primary standard. A spirometer, a "frictionless" piston meter, or a Roots meter can
serve as such a standard.
Orifice Transfer Standard - The high volume sampler calibration orifice consists of
a 3.175 cm (1.25 in) diameter hole in the end cap of 7.62 cm (13 in) diameter by
20.3 cm (8 in) long hollow metal cylinder. This orifice is mounted tightly to the filter
support in place of the inlet during calibration. A small tap on the side of the cylinder
is provided to measure the pressure drop across the orifice. A flow rate of 1132 l/min
through the orifice typically results in a pressure difference of several inches of
water. The relationship between pressure difference and flow rate is established via
a calibration curve derived from measurements against a primary standard at
standard temperature and pressure. Flow resistances that simulate filter resistances
are introduced at the end of the calibrator opposite the orifice by a set of perforated
circular disks.
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