1065.920—PEMS Calibrations and verifications.
(a) Subsystem calibrations and verifications.
Use all the applicable calibrations and verifications in subpart D of this part, including the linearity verifications in § 1065.307, to calibrate and verify PEMS. Note that a PEMS does not have to meet the system-response and updating-recording verifications of §§ 1065.308 and 1065.309 if it meets the overall verification described in paragraph (b) of this section. This section does not apply to ECM signals.
(b) Overall verification.
We require only that you maintain a record showing that the particular make, model, and configuration of your PEMS meets this verification. We recommend that you generate your own record to show that your specific PEMS meets this verification, but you may also rely on data and other information from the PEMS manufacturer. If you upgrade or change the configuration of your PEMS, your record must show that your new configuration meets this verification. The verification consists of operating an engine over a duty cycle in the laboratory and statistically comparing data generated and recorded by the PEMS with data simultaneously generated and recorded by laboratory equipment as follows:
(1)
Mount an engine on a dynamometer for laboratory testing. Prepare the laboratory and PEMS for emission testing, as described in this part, to get simultaneous measurements. We recommend selecting an engine with emission levels close to the applicable duty-cycle standards, if possible.
(i)
Engine operation that represents normal in-use speeds, loads, and degree of transient activity. Consider using data from previous field tests to generate a cycle.
(iii)
At least 50% of engine operating time must include at least 10 valid test intervals for calculating emission levels for field testing. For example, for highway compression-ignition engines, select a duty cycle in which at least 50% of the engine operating time can be used to calculate valid NTE events.
(3)
Starting with a warmed-up engine, run a valid emission test with the duty cycle from paragraph (b)(2) of this section. The laboratory and PEMS must both meet applicable validation requirements, such as drift validation, hydrocarbon contamination validation, and proportional validation.
(4)
Determine the brake-specific emissions for each test interval for both laboratory and the PEMS measurements, as follows:
(i)
For both laboratory and PEMS measurements, use identical values to determine the beginning and end of each test interval.
(ii)
For both laboratory and PEMS measurements, use identical values to determine total work over each test interval.
(iii)
If the standard-setting part specifies the use of a measurement allowance for field testing, also apply the measurement allowance during calibration using good engineering judgment. If the measurement allowance is normally added to the standard, this means you must subtract the measurement allowance from the measured PEMS brake-specific emission result.
(ii)
The entire set of test-interval results passes the 95% confidence alternate-procedure statistics for field testing (t -test and F -test) specified in subpart A of this part.