Chapter 4 Calibration And Particle Size Selection; Factory Calibration - Thermo Scientific MIE ADR-1500 Instruction Manual

Calibration and Particle Size Selection
Calibration
4-2 MIE ADR-1500 Instruction Manual
Factory
For mass concentration measurements, each ADR-1500 is factory
calibrated against a set of reference monitors that, in turn, are periodically
calibrated against a gravimetric standard traceable to the National Institute
of Standards and Testing (NIST).
The primary factory reference method consists of generating a dust aerosol
by means of a fluidized bed generator, and injecting continuously the dust
into a mixing chamber from which samples are extracted concurrently by
two reference filter collectors and by two master real-time monitors that are
used for the routine calibration of every ADR-1500.
The primary dust concentration reference value is obtained from the weight
increase of the two filters due to the dust collected over a measured period
of time, at a constant and known flow rate. The two master real-time
monitors are then adjusted to agree with the reference mass concentration
value (obtained from averaging the measurements of the two gravimetric
filters) to within ±1%.
Three primary NIST traceable measurements are involved in the
determination of the reference mass concentration: the weight increment
from the dust collected on the filter, the sampling flow rate, and the
sampling time. Additional conditions that must be met are: a) suspended
dust concentration uniformity at all sampling inlets of the mixing chamber;
b) identical sample transport configurations leading to reference and
instrument under calibration; and c) essentially 100% collection efficiency
of filters used for gravimetric reference for the particle size range of the test
dust.
The test dust used for the factory calibration of the ADR-1500 is SAE Fine
(ISO Fine) supplied by Powder Technology, Inc. It has the following
physical characteristics (as dispersed into the mixing chamber):
Mass median aerodynamic particle diameter: 2 to 3 μm
●
Geometric standard deviation of lognormal size distribution: 2.5
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Bulk density: 2.60 to 2.65 g/cm
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Refractive index: 1.54
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In addition to the mass calibration described above, the ADR-1500 is
factory calibrated for temperature, relative humidity, barometric pressure,
and volumetric flow rate using NIST-traceable standards.
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