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

section comprises two independent flow controls that can be varied individually to
provide a dilution ration of up to 1,000 to 1. The GPT section comprises a
current-regulated ozone generator through which a portion of the dilution air
flows even when the ozonator is not in operation. For dynamic dilution, the
metered NO combines with this portion of the dilution air and passes through the
reaction chamber. It then combines with the balance of the dilution air and
passes through the sampling manifold. For GPT the flow path is the same
except that a portion of the oxygen in the air passing through the ozone
generator is converted to ozone.
10.2.1 Air Flow Controller - A device capable of maintaining constant clean-air flow up
to 5 L/min within + 2% of the required flow rate.
10.2.2 Air Flowmeter - A calibrated flowmeter capable of measuring air flow rates
within + 2%.
10.2.3 Nitric Oxide Flow Controller - A device capable of maintaining constant NO
flow within + 2% of the required flow rate.
10.2.4 Nitric Oxide Flowmeter - A calibrated flowmeter capable of measuring NO flow
rates within + 2%.
10.2.5 Two-Stage Regulator - The two-stage pressure regulator for the standard NO
cylinder must be of stainless steel to prevent any reaction of the NO gas.
10.2.6 Ozone Generator - The generator must be capable of generating stable levels of
O3 for the GPT of NO to provide NO2 concentrations throughout the calibration
range.
10.2.7 Reaction Chamber - The chamber used for the reaction of O3 with excess NO
should be of sufficient volume that the residence time is not less than 2 minutes
(11).
10.2.8 Mixing Chamber - A chamber used to allow thorough mixing of reaction
products and dilution air.
10.2.9 Sampling Manifold - The sampling manifold should be of adequate design to
insure against any pressure buildup. It must have a vent to insure atmospheric
pressure at the manifold, and for safety considerations to direct excess
calibration air streams to an exhaust system.
10.3 Procedure - Prior to start of calibration, for safety purposes, insure proper
venting of the analyzer exhaust and the calibration system have excess flow.
Insure that the analyzer and the calibration system have been on for a time
sufficient to provide stable operation.
135