Particulate Matter Concentration and Limits

Mass Flow Rate – Recently at a training course on Dust Control where Gerry Kuhn and Chris Loans presented, the question of dilution of particulate matter levels for the purpose of meeting legislated concentration limits was raised.

Training was organised by Tour De Force Training Solutions – Highly recommended.  Excellent training facilities and well organised.

After phoning a friend, the conclusion in this regard is that yes, dilution of the stack before the isokinetic measurement or continuous measurement point will dilute the particulate matter concentration and could be used to decrease the values below the limit.

The NEMA 2004 Act using the Section 21 List of Activities does specify that a mass flow rate must be reported.  See quoted portion below.

“(2) The report contemplated in 8(1) shall include-
(a) The name, description and license reference number of the plant as reflected in the
Atmospheric Emission License.
(b) Where periodic emission monitoring is required for a listed activity in terms of the
minimum emission standards as contained in Part 3 –
(i) the name and address of the accredited measurement service-provider that carried
out or verified the emission test, including the test report produced by the accredited
measurement service-provider;
(ii) the date and time on which the emission test was carried out;
(iii) a declaration by the Atmospheric Emission License holder to the effect that normal
operating conditions were maintained during the emission tests;
(iv) the total volumetric flow of gas, expressed in normal cubic meters (Nm3) per unit
time and mass flow (kg per unit time) being emitted by the listed activity or
activities measured during the emission test, as the average of at least two (2)
measurements;
(v) the concentration or mass of pollutant for which emissions standards have been set
in this Notice emitted by listed activity or activities as the average of at least two (2)
measurements; each measured over a minimum sample period of 60 minutes and a
maximum of 8 hours to obtain a representative sample, and
(vi) the method or combination of methods used for determining the flow rate and
concentration as contemplated in Section 4.”

The phone a friend advice was that even though this is possible, the dilution of the gases being emitted will not be achieved due to the normalisation and the behaviour of a gas in a stack.  This will mean that the client will not be compliant with regard to the gas concentration levels, even though the particulate matter concentrations are within the limits.  The logic is that if the gas concentrations are controlled to the limit then the particulate matter concentrations will also be compliant.

Noted, there are some issues here and there will be situations where the gas concentration is within the limit and the particulate matter concentration is above the limit (possibly due to a poorly maintained dust control system – Bag Plant, Cyclone etc) and then dilution could be used to meet the particulate matter limit.

The advice from “phone a friend” was that the local municipalities were meant to use the Act to generate their own internal limits for the activities within their areas they service to adequately describe the environmental emissions from the various activities.  This might still happen in the future and this would then presumably provide for some limits for particulate matter in mass per flow units, based on a baseline measurements taken.

Please contact us regarding any additional queries.

DustWatch – 082 875 0209 – Chris Loans and Gerry Kuhn (083 308 4764)

Fallout Dust Monitoring Specialists.

Fallout Dust Monitoring Specialists

Fallout Dust Monitoring Specialists

Stack Sampling can be done by : Exco Services – Highly recommended for Stack Monitoring in Gauteng and the whole of South Africa.

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