Document ID: chunk:federal_register_of_legislation:F2008C00323:reg:120:p14
Version: federal_register_of_legislation:F2008C00323
Segment Type: reg
Provision Reference: reg 120 (pt 14/23)
Character Range: 274440–277368

less than 5 per cent of the NO concentration). The NOx analyser shall be in the NO mode so that the span gas does not pass through the converter. Record the indicated concentration.

         3.2. Via a T-fitting, oxygen or synthetic air is added continuously to the span gas flow until the concentration indicated is about 10 per cent less than the indicated calibration concentration given in paragraph 3.1. above. Record the indicated concentration (C). The ozonator is kept deactivated throughout this process.

         3.3. The ozonator is now activated to generate enough ozone to bring the NO concentration down to 20 per cent (minimum 10 per cent) of the calibration concentration given in paragraph 3.1. above. Record the indicated concentration (d).

         3.4.  The NOx analyser is then switched to the NOx mode, which means that the gas mixture (consisting of NO, NO2, O2 and N2 ) now passes through the converter. Record the indicated concentration (a).

         3.5.  The ozonator is now deactivated. The mixture of gases described in paragraph 3.2. above passes through the converter into the detector. Record the indicated concentration (b).
Figure 6/1

Diagram of NOx converter efficiency devices

         3.6. With the ozonator deactivated, the flow of oxygen or synthetic air is also shut off.  The NO2 reading of the analyser shall then be no more than 5 per cent above the figure given in paragraph 3.1. above.

         3.7. The efficiency of the NOx converter is calculated as follows:

   Efficiency (per cent) = (1+  a-b  ) . 100
   c-d

         3.8.  The efficiency of the converter shall not be less than 95 per cent.

         3.9.  The efficiency of the converter shall be tested at least once a week.

         4.  CALIBRATION OF THE CVS SYSTEM

         4.1. The CVS system shall be calibrated by using an accurate flowmeter and a restricting device. The flow through the system shall be measured at various pressure readings and the control parameters of the system measured and related to the flows.

         4.1.1. Various types of flowmeter may be used, e.g. calibrated venturi, laminar flow-meter, calibrated turbine-meter, provided that they are dynamic measurement systems and can meet the requirements of paragraphs 4.4.1. and 4.4.2. of Annex 4.

         4.1.2.  The following paragraphs give details of methods of calibrating PDP and CFV units, using a laminar flowmeter, which gives the required accuracy, together with a statistical check on the calibration validity.

         4.2. Calibration of the positive displacement pump (PDP)

         4.2.1. The following calibration procedure outlines the equipment, the test configuration and the various parameters which are measured to establish the flow-rate of the CVS pump. All the parameters related to the pump are simultaneously measured with the parameters related to the flowmeter which is connected in series with the