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74
PM10 are computed using flow rates corrected to EPA reference conditions of temperature
and pressure (Qstd).
8.2 Flow Rate Calibration Procedure.
8.2.1 PM10 samplers employ various types of flow control and flow measurement devices. The
specific procedure used for flow rate calibration or verification will vary depending on the
type of flow controller and flow indicator employed. Calibration in terms of actual volumetric
flow rates (Qa) is generally recommended, but other measures of flow rate (eg. Qstd) may be
used provided the requirements of section 8.1 are met. The general procedure given here is
based on actual volumetric flow units (Qa) and serves to illustrate the steps involved in the
calibration of a PM10 sampler. Consult the sampler manufacturer's instruction manual and
Reference 2 for specific guidance on calibration. Reference 14 provides additional information
on the use of the commonly used measures of flow rate and their interrelationships.
8.2.2 Calibrate the flow rate transfer standard against a primary flow or volume standard traceable
to NBS. Establish a calibration relationship (eg. An equation or family of curves) such that
traceability to the primary standard is accurate to within 2 percent over the expected range of
ambient conditions (ie temperatures and pressures) under which the transfer standard will be
used. Recalibrate the transfer standard periodically.
8.2.3 Following the sampler manufacturer's instruction manual remove the sampler inlet and connect
the flow rate transfer standard to the sampler such that the transfer standard accurately
measures the sampler's flow rate. Make sure there are no leaks between the transfer standard
and the sampler.
8.2.4 Choose a minimum of three flow rates (actual m3/min), spaced over the acceptable flow rate
range specified for the inlet (see 7.1.2) that can be obtained by suitable adjustment of the
sampler flow rate. In accordance with the sampler manufacturer's instruction manual, obtain
or verify the calibration relationship between the flow rate (actual m3/min) as indicated by the
transfer standard and the sampler's flow indicator response. Record the ambient temperatures
and barometric pressure. Temperature and pressure corrections to subsequent flow indicator
readings may be required for certain types of flow measurement devices. When such
corrections are necessary, correctin on an individual or daily basis is preferable. However,
seasonal average temperature and average barometric pressure for the sampling site may be
incorporated into the sampler calibration to avoid daily corrections. Consult the sampler
manufacture's instruction manual and Reference 2 for additional guidance.
8.2.5 Following calibration, verify that the sampler is operation at its design flow rate (actual
m3/min) with a clean filter in place.
8.2.6 Replace the sampler inlet.
9.0 Procedure.
9.1 The sampler shall be operated in accordance with the specific guidance provided in the
sampler manufacturer's instruction manual and in Reference 2. The general procedure given
here assumes that the sampler's flow rate calibration is based on flow rates at ambient
conditions (Qa) and serves to illustrate the steps involved in the operation of a PM10
sampler.
9.2 Inspect each filter for pinholes, particles, and other imperfections, establish a filter information
record and assign an identification number to each filter.
9.3 Equilibrate each filter in the conditions environment (see 7.4) for at least 24 hours.
9.4 Following equilibration, weigh each filter and record the presampling weight with the filter
identification number.
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