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the sensitivity of the inlet to variations in flow rate and on the particle distribution in the
atmosphere during the sampling period. The use of a flow control device (section 7.1.3) is
required to minimize this error.
6.6 Air Volume Determination. Errors in the air volume determination may result from errors in
the flow rate and/or sampling time measurements. The flow control device serves to minimize
errors in the flow rate determination, and an elapsed time meter (section 7.1.5) is required to
minimize the error in the sampling time measurement.
7.0 Apparatus.
7.1 PM10 Sampler.
7.1.1 The sampler shall be designed to:
a. Draw the air sample into the sampler inlet and through the particle collection filter at a
uniform face velocity.
b. Hold and seal the filter in a horizontal position so that sample air is drawn downward
through the filter.
c. Allow the filter to be installed and removed conveniently.
d. Protect the filter and sampler from precipitation and prevent insects and other debris from
being sampled.
e. Minimize air leaks that would cause error in the measurement of the air volume passing
through the filter.
f. Discharge exhaust air at a sufficient distance from the sampler inlet to minimize the
sampling of exhaust air.
g. Minimize the collection of dust from the supporting surface.
7.1.2 The sampler shall have a sample air inlet system that, when operated within a
specified flow rate range, provides particle size discrimination characteristics
meeting all of the applicable performance specifications prescribed in Part 53 of this
this chapter. The sampler inlet shall show no significant wind direction dependence.
The latter requirement can generally be satisfied by an inlet shape that is circularly
symmetrical about a vertical axis.
7.1.3 The sampler shall have a flow control device capable of maintaining the sampler's
operating flow rate within the flow rate limits specified for the sampler inlet over
normal variations in line voltage and filter pressure drop.
7.1.4 The sampler shall provide a means to measure the total flow rate during the sampling
period. A continuous flow recorder is recommended but not required. The flow
measurement device shall be accurate to +/-2 percent.
7.1.5 A timing/control device capable of starting and stopping the sampler shall be used to
obtain a sample collection period of 24 +/-1 hr (1,440 +/-60 min). An elapsed time
meter, accurate to within +/-15 minutes, shall be used to measure sampling time.
This meter is optional for samplers with continuous flow recorders if the sampling
time measurement obtained by means of the recorder meets the +/-15 minute
accuracy specification.
7.1.6 The sampler shall have an associated operation or instruction manual as required by
Part 53 of this chapter which includes detailed instructions on the calibration,
operation, and maintenance of the sampler.
7.2 Filters.
7.2.1 Filter Medium. No commercially available filter medium is ideal in all respects for
all samplers. The user's goals in sampling determine the relative importance of
various filter characteristics (e.g., cost, ease of handling, physical and chemical
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