40 CFR 86.309-79 - Sampling and analytical system; schematic drawing.
(a) Any variation from the specifications in this subpart including performance specifications and emission detection methods may be used only with prior approval by the Administrator.
(1) An example of a sampling and analytical system which may be used for testing under this subpart is shown in Figure D79-1. All components or parts of components that are wetted by the sample or corrosive calibration gases shall be either chemically cleaned stainless steel or inert material, e.g. polytetrafluoroethylene resin. The use of “gauge savers” or “protectors” with nonreactive diaphragms to reduce dead volumes is permitted. The specific detection methods to be used for each exhaust component can be found in § 86.316 for CO. § 86.317 for HC, and § 86.318 for NOX. Additional components such as instruments, valves, solenoids, pumps, switches, etc. may be employed to provide additional information and coordinate the functions of the component systems.
(2) The following requirements must be incorporated in each system used for testing under this subpart.
(ii) The sample transport system from the engine exhaust pipe to the HC analyzer and the NOX analyzer must be heated as is indicated in Figure D79-1.
(iii) Carbon monoxide and carbon dioxide measurements must be made on a dry basis. Specific requirements for the means of drying the sample can be found in § 86.309 (b)(5) and § 86.311(e).
(iv) All NDIR analyzers must have a pressure gauge immediately downstream of the analyzer. The gauge tap must be within 2 inches of the analyzer exit port. Gauge specifications can be found in § 86.309(b)(3).
(v) All bypass and analyzer flows exiting the analysis system must be measured. Capillary flows such as in HFID and CL analyzers are excluded. For each ND IR analyzer with a flow meter located upstream of the analyzer, an upstream pressure gauge must be used. The gauge tap must be within 2 inches of the analyzer entrance port.
(vi) Calibration or span gases for the NOX measurement system must pass through the NO2 to NO converter.
(c) System components list. The following is a list of components shown in Fig. D79-1 by numeric identifier.
(1) Filters. Glass fiber filter paper is permitted for F1, F2, and F3. Optional filter F4 is a coarse filter for large particulates.
(3) Gauges. Downstream gauges are required for any system used for testing under this subpart. Upstream gauges may be required under this subpart per § 86.309(b)(2)(v).
(ii) Downstream gauges G3 and G4 measure the exit pressure of the CO and CO2 analyzers. If the normal operating range of the downstream gauges is less than 3 inches of water, then the downstream gauges must be capable of reading both pressure and vacuum.
(5) Water traps. Water traps WT1, and WT2 to remove water from the sample. A water trap performing the function of WT1 and meeting the specifications in § 86.311(e) is required for any system used for testing under this subpart. Chemical dryers are not an acceptable method of removing the water. Water removal by condensation is acceptable. Means other than condensation may be used only with prior approval from the Administrator.
(i) R1, R3, R4, and R6—linepressure regulators to control span pressure at inlet to flow control valves.
(ii) R2 and R5—back presssure regulators to control sample pressure at inlet to flow control valves.
(ii) V2—optional heated selector valve to purge the sample probe, perform leak checks, or to perform hang-up checks.
(9) Temperature sensor. A temperature sensor (T1) to measure the NO2 to NO converter temperature is required for any system used for testing under this subpart.
Title 40 published on 2013-07-01
no entries appear in the Federal Register after this date.