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2. Useful conversions and formulas for air dispersion modeling

   en.wikipedia.org/wiki/Useful_conversions_and...

   A normal cubic meter (Nm 3) is the metric expression of gas volume at standard conditions and it is usually (but not always) defined as being measured at 0 °C and 1 atmosphere of pressure. A standard cubic foot (scf) is the USA expression of gas volume at standard conditions and it is often ( but not always ) defined as being measured at 60 ...

3. Air pollutant concentrations - Wikipedia

   en.wikipedia.org/wiki/Air_pollutant_concentrations

   Environmental agencies in the USA often use the terms "dscf" or "scfd" to denote a "standard" cubic foot of dry gas. Likewise, they often use the terms "dscm" or "scmd" to denote a "standard" cubic meter of gas. Since there is no universally accepted set of "standard" temperature and pressure, such usage can be and is very confusing.

4. Threshold limit value - Wikipedia

   en.wikipedia.org/wiki/Threshold_limit_value

   Its units are in parts per million (ppm) for gases and in milligrams per cubic meter (mg/m 3) for particulates such as dust, smoke and mist. The basic formula for converting between ppm and mg/m 3 for gases is ppm = (mg/m^3) * 24.45 / molecular weight. This formula is not applicable to airborne particles.

5. Peak programme meter - Wikipedia

   en.wikipedia.org/wiki/Peak_programme_meter

   A typical British quasi-PPM. Each division between '1' and '7' is exactly four decibels and '6' is the intended maximum level. A peak programme meter (PPM) is an instrument used in professional audio that indicates the level of an audio signal. Different kinds of PPM fall into broad categories: True peak programme meter. This shows the peak ...

6. Particulate matter sampler - Wikipedia

   en.wikipedia.org/wiki/Particulate_matter_sampler

   Modern particulate samplers use a volumetric flow control system that pulls air through the particle separator at the velocity required to achieve the desired cutpoint. For air pollution applications, the definition of "particulate" does not include uncombined water, and water from a particulate sample must be removed before it is weighed.

7. Clean air delivery rate - Wikipedia

   en.wikipedia.org/wiki/Clean_Air_Delivery_Rate

   The clean air delivery rate (CADR) is a figure of merit that is the cubic feet per minute (CFM) of air that has had all the particles of a given size distribution removed. For air filters that have air flowing through them, it is the fraction of particles (of a particular size distribution) that have been removed from the air, multiplied by the ...