Document ID: chunk:federal_register_of_legislation:F2012C00283:reg:21:p30
Version: federal_register_of_legislation:F2012C00283
Segment Type: reg
Provision Reference: reg 21 (pt 30/39)
Character Range: 339567–342582

calibration. Linearity of response is calculated as the square of the Pearson product moment correlation coefficient (R2) of the two data sets and shall be equal to or greater than 0.97. In calculating both the gradient and R2 the linear regression shall be forced through the origin (zero concentration on both instruments).
               In the reference PNC case, calibration shall be undertaken using at least six standard concentrations across the PNC's measurement range. At least three points shall be at concentrations below 1,000 cm-3, the remaining concentrations shall be linearly spaced between 1,000 cm-3 and the maximum of the PNC's range in single particle count mode. These points will include a nominal zero concentration point produced by attaching HEPA filters of at least class H13 of EN 1822:2008, or equivalent performance, to the inlet of each instrument. With no calibration factor applied to the PNC under calibration, measured concentrations shall be within ±10 per cent of the standard concentration for each concentration, with the exception of the zero point, otherwise the PNC under calibration shall be rejected. The gradient from a linear regression of the two data sets shall be calculated and recorded. A calibration factor equal to the reciprocal of the gradient shall be applied to the PNC under calibration. Linearity of response is calculated as the square of the Pearson product moment correlation coefficient (R2) of the two data sets and shall be equal to or greater than 0.97. In calculating both the gradient and R2 the linear regression shall be forced through the origin (zero concentration on both instruments).
              2.1.4. Calibration shall also include a check, against the requirements in paragraph 1.3.4.8., on the PNC's detection efficiency with particles of 23 nm electrical mobility diameter. A check of the counting efficiency with 41 nm particles is not required.
              2.2. Calibration/Validation of the Volatile Particle Remover
              2.2.1. Calibration of the VPR's particle concentration reduction factors across its full range of dilution settings, at the instrument's fixed nominal operating temperatures, shall be required when the unit is new and following any major maintenance. The periodic validation requirement for the VPR's particle concentration reduction factor is limited to a check at a single setting, typical of that used for measurement on diesel particulate filter equipped vehicles. The Technical Service shall ensure the existence of a calibration or validation certificate for the volatile particle remover within a 6 month period prior to the emissions test. If the volatile particle remover incorporates temperature monitoring alarms a 12 month validation interval shall be permissible.
               The VPR shall be characterised for particle concentration reduction factor with solid particles of 30 nm, 50 nm and 100 nm electrical mobility diameter. Particle concentration reduction factors (fr(d)) for