# Title 40

## SECTION 1065.545

### 1065.545 Verification of proportional flow control for batch sampling.

§ 1065.545 Verification of proportional flow control for batch sampling.For any proportional batch sample such as a bag or PM filter, demonstrate that proportional sampling was maintained using one of the following, noting that you may omit up to 5% of the total number of data points as outliers:

(a) For any pair of flow rates, use recorded sample and total
flow rates, where total flow rate means the raw exhaust flow rate
for raw exhaust sampling and the dilute exhaust flow rate for CVS
sampling, or their 1 Hz means with the statistical calculations in
§ 1065.602. Determine the standard error of the estimate,
*SEE*, of the sample flow rate versus the total flow rate. For
each test interval, demonstrate that *SEE* was less than or
equal to 3.5% of the mean sample flow rate.

(b) For any pair of flow rates, use recorded sample and total flow rates, where total flow rate means the raw exhaust flow rate for raw exhaust sampling and the dilute exhaust flow rate for CVS sampling, or their 1 Hz means to demonstrate that each flow rate was constant within ±2.5% of its respective mean or target flow rate. You may use the following options instead of recording the respective flow rate of each type of meter:

(1) *Critical-flow venturi option.* For critical-flow
venturis, you may use recorded venturi-inlet conditions or their 1
Hz means. Demonstrate that the flow density at the venturi inlet
was constant within ±2.5% of the mean or target density over each
test interval. For a CVS critical-flow venturi, you may demonstrate
this by showing that the absolute temperature at the venturi inlet
was constant within ±4% of the mean or target absolute temperature
over each test interval.

(2) *Positive-displacement pump option.* You may use
recorded pump-inlet conditions or their 1 Hz means. Demonstrate
that the flow density at the pump inlet was constant within ±2.5%
of the mean or target density over each test interval. For a CVS
pump, you may demonstrate this by showing that the absolute
temperature at the pump inlet was constant within ±2% of the mean
or target absolute temperature over each test interval.

(c) Using good engineering judgment, demonstrate with an engineering analysis that the proportional-flow control system inherently ensures proportional sampling under all circumstances expected during testing. For example, you might use CFVs for both sample flow and total dilute exhaust (CVS) flow and demonstrate that they always have the same inlet pressures and temperatures and that they always operate under critical-flow conditions.

[79 FR 23777, Apr. 28, 2014]