86.110-90—Exhaust gas sampling system; diesel vehicles.
(a) General.
The exhaust gas sampling system described in this paragraph is designed to measure the true mass of both gaseous and particulate emissions in the exhaust of either diesel light-duty vehicles and light-duty trucks. This system utilizes the CVS concept (described in § 86.109) of measuring mass emissions. The mass of gaseous emissions is determined from the sample concentration and total flow over the test period. The mass of particulate emissions is determined from a proportional mass sample collected on a filter and from the total flow over the test period. General requirements are as follows:
(1)
This sampling system requires the use of a PDP-CVS or a CFV sample system with heat exchanger connected to a dilution tunnel. Figure B90-5 is a schematic drawing of the PDP system. Figure B90-6 is a schematic drawing of the CFV system (methanol-fueled Otto-cycle vehicles may be tested using this test equipment.)
Code of Federal Regulations
Code of Federal Regulations
482
Code of Federal Regulations
Code of Federal Regulations
483
(2)
Bag, HFID, and particulate sampling capabilities as shown in Figure B90-5 (or Figure B90-6) are required to provide both gaseous and particulate emissions sampling capabilities from a single system.
(3)
Petroleum-fueled diesel vehicles require a heated flame ionization detector (HFID) (375°±20 °F (191°±11 °C)) sample for hydrocarbon analysis. The HFID sample must be taken directly from the diluted exhaust stream through a heated probe in the dilution tunnel.
(4)
Methanol-fueled vehicles require the use of a heated flame ionization detector (HFID) (235°±15 °F (113°±8 °C)) for hydrocarbon analysis. With an HFID, the hydrocarbon analysis can be made on the bag sample and the methanol and formaldehyde analyses are performed on the samples collected for these purposes (Figures B90-2 and B90-3). NOTE: For 1990 through 1994 model year methanol-fueled vehicles, methanol and formaldehyde sampling may be omitted provided the bag sample is analyzed using a HFID calibrated with methanol.
(i)
A tailpipe to dilution tunnel duct of unrestricted length maintained at 235° ±15 °F (113° ±8 °C) through heating and cooling as required; or
(ii)
Using short duct (up to 12 feet long) constructed of smooth wall pipe with a minimum of flexible sections maintained at 235° ±15 °F (113° ±8 °C) prior to the test and during breaks in testing (insulation may remain in place and/or heating may occur during testing provided maximum temperature is not exceeded); or
(iv)
Omitting the duct and performing the exhaust gas dilution function at the vehicle tailpipe exit.
(6)
Since various configurations can produce equivalent results, exact conformance with these drawings is not required. Additional components such as instruments, valves, solenoids, pumps, and switches may be used to provide additional information and coordinate the functions of the component systems.
(7)
Other sampling systems may be used if shown to yield equivalent results and if approved in advance by the Administrator.
(b) Component description—petroleum-fueled diesel vehicles.
The components necessary for petroleum fueled diesel vehicle exhaust sampling shall meet the following requirements:
(1)
The PDP-CVS, Figure B90-5, shall conform to all of the requirements listed for the exhaust gas PDP-CVS ( § 86.109(b) ), with one exception: a flow rate of sufficient volume is required to maintain the diluted exhaust stream, from which the particulate sample flow is taken, at a temperature of 125 °F (52 °C) or less.
(2)
The CFV sample system, Figure B90-6, shall conform to all of the requirements listed for the exhaust gas CFV sample system ( § 86.109(c) ), with four exceptions:
(i)
A flow rate of sufficient volume is required to maintain the diluted exhaust stream, from which the particulate sample flow is taken, at a temperature of 125 °F (52 °C) or less.
(iii)
The gas mixture temperature, measured at a point immediately ahead of the critical flow venturi, shall be within ±20 °F (11 °C) of the designed operating temperature at the start of the test. The gas mixture temperature variation from its value at the start of the test shall be limited to ±20 °F (11 °C) during the entire test. The temperature measuring system shall have an accuracy and precision of ±2 °F (1.1 °C).
(3)
The transfer of heat from the vehicle exhaust gas shall be minimized between the point where it leaves the vehicle tailpipe(s) and the point where it enters the dilution tunnel airstream. To accomplish this, a short length (not more than 12 feet (365 cm) if uninsulated, or not more than 20 feet (610 cm) if insulated) of smooth stainless steel tubing from the tailpipe to the dilution tunnel is required. This tubing shall have a maximum inside diameter of 4.0 inches (10.2 cm). Short sections of flexible tubing at connection points are allowed.
(4)
The vehicle exhaust shall be directed downstream at the point where it is introduced into the dilution tunnel.
(i)
Sized to permit development of turbulent flow (Reynold's No. >>4000) and complete mixing of the exhaust and dilution air between the mixing orifice and each of the two sample probes (i.e., the particulate probe and the heated HC sample probe). It is recommended that uniform mixing be demonstrated by the user.
(iii)
Constructed of electrically conductive material which does not react with the exhaust components.
(7)
The temperature of the diluted exhaust stream inside of the dilution tunnel shall be sufficient to prevent water condensation. However, the sample zone dilute exhaust temperature shall not exceed 125 °F (52 °C) at any time during the test.
(i)
Installed facing upstream at a point where the dilution air and exhaust are well mixed (i.e., near the tunnel centerline, approximately 10 tunnel diameters downstream from the point where the exhaust enters the dilution tunnel).
(ii)
Sufficiently distant (radially) from the total hydrocarbon probe so as to be free from the influence of any wakes or eddies produced by the total hydrocarbon probe.
(iv)
The distance from the sampling tip to the filter holder shall be at least 5 probe diameters (for filters located inside of the tunnel), but not more than 40.0 inches (102 cm) for filters located outside of the dilution tunnel.
(vi)
Configured so that a clean particulate filter (including back-up filter) can be selected simultaneously with the selection of an empty gaseous emissions bag.
(9)
The flow rate through the particulate probe shall be maintained to a constant value within ±5 percent of the set flow rate.
(10)
The particulate sample pump shall be located sufficiently distant from the dilution tunnel so that the inlet gas temperature is maintained at a constant temperature (±5.0 °F (2.8 °C)).
(11)
The gas meters or flow instrumentation shall be located sufficiently distant from the tunnel so that the inlet gas temperature remains constant (±5.0 °F (2.8 °C)).
(i)
Installed facing upstream at a point where the dilution air and exhaust are well mixed (i.e., approximately 10 tunnel diameters downstream from the point where the exhaust enters the dilution tunnel).
(ii)
Sufficiently distant (radially) from the particulate probe so as to be free from the influence of any wakes or eddies produced by the particulate probe.
(iii)
Heated and insulated over the entire length to maintain a 375°±20 °F (191°±11 °C) wall temperature.
(13)
It is intended that the total hydrocarbon probe be free from cold spots (i.e., free from spots where the probe wall temperature is less than 355 °F). This will be determined by a temperature sensor located on a section of the probe wall outside of the dilution tunnel. The temperature sensor shall be insulated from any heating elements on the probe. The sensor shall have an accuracy and precision of ±2 °F (1.1 °C).
(i)
At 375 °F±10 °F (191 °C±6 °C) immediately before the heated filter. This will be determined by a temperature sensor located immediately upstream of the filter. The sensor shall have an accuracy and precision of ±2 °F (1.1 °C).
(ii)
At 375 °F±10 °F (191 °C±6 °C) immediately before the HFID. This will be determined by a temperature sensor located at the exit of the heated sample line. The sensor shall have an accuracy and precision of ±2 °F (1.1 °C).
(15)
It is intended that the dilute exhaust gas flowing in the total hydrocarbon sample system be between 365 °F and 385 °F (185 °C and 197 °C).
(c) Component description—methanol-fueled diesel vehicles.
The components necessary for methanol-fueled diesel vehicle exhaust sampling shall meet the following requirements:
(1)
The PDP-CVS, Figure B90-5 shall conform to all of the requirements listed for the exhaust gas PDP-CVS ( § 86.109 (a)(3) and (b) ), with one exception: a flow rate of sufficient volume is required to maintain the diluted exhaust stream, from which the particulate sample flow is taken, at a temperature of 125 °F (52 °C) or less and shall prevent the condensation of water vapor in the dilution tunnel.
(2)
The CFV sample system, Figure B90-6 shall conform to all of the requirements listed for the exhaust gas CFV sample system ( § 86.109 (a)(4) and (c) ), with four exceptions:
(i)
A flow rate of sufficient volume is required to maintain the diluted exhaust stream, from which the particulate sample flow is taken, at a temperature of 125 °F (52 °C) or less and shall prevent the condensation of water vapor in the dilution tunnel.
(iii)
The gas mixture temperature, measured at a point immediately ahead of the critical flow venturi, shall be within ±20 °F (11 °C) of the designed operating temperature at the start of the test. The gas mixture temperature variation from its value at the start of the test shall be limited to ±20 °F (11 °C) during the entire test. The temperature measuring system shall have an accuracy and precision of ±2 °F (1.1 °C).
(3)
Losses of methanol due to condensation of water in the duct connecting the vehicle tail pipe to the dilation tunnel must be minimized. This may be accomplished by:
(i)
The use of a duct of unrestricted length maintained at 235°±15 °F (113°±8 °C) through heating and cooling as required, or
(ii)
The use of a short duct (up to 12 feet long) constructed of smooth wall pipe with a minimum of flexible sections maintained at 235°±15 °F (113°±8 °C) prior to the test and during breaks in testing (insulation may remain in place and/or heating may occur during testing provided maximum temperature is not exceeded); or
(iv)
Omitting the duct and performing the exhaust gas dilution function at the vehicle tailpipe exit.
(4)
The vehicle exhaust shall be directed downstream at the point where it is introduced into the dilution tunnel.
(i)
Sized to permit development of turbulent flow (Reynold's No. >>4000) and complete mixing of the exhaust and dilution air between the mixing orifice and the particulate sample probe. It is recommended that uniform mixing be demonstrated by the user.
(iii)
Constructed of electrically conductive material which does not react with the exhaust components.
(7)
The temperature of the diluted exhaust stream inside of the dilution tunnel shall be sufficient to prevent water condensation. However, the sample zone dilute exhaust temperature shall not exceed 125 °F (52 °C) at any time during the test.
(i)
Installed facing upstream at a point where the dilution air and exhaust are well mixed (i.e., near the tunnel centerline, approximately 10 tunnel diameters downstream from the point where the exhaust enters the dilution tunnel).
(ii)
Sufficiently distant (radially) from the total hydrocarbon probe so as to be free from the influence of any wakes or eddies produced by the total hydrocarbon probe.
(iv)
The distance from the sampling tip to the filter holder shall be at least 5 probe diameters (for filters located inside of the tunnel), but not more than 40.0 inches (102 cm) for filters located outside of the dilution tunnel.
(vi)
Configured so that a clean particulate filter (including back up filter) can be selected simultaneously with the selection of an empty gaseous emissions bag.
(9)
The flow rate through the particulate probe shall be maintained to a constant value within ±5 percent of the set flow rate.
(10)
The particulate sample pump shall be located sufficiently distant from the dilution tunnel so that the inlet gas temperature is maintained at a constant temperature (±5.0 °F (2.8 °C)).
(11)
The gas meters or flow instrumentation shall be located sufficiently distant from the tunnel so that the inlet gas temperature remains constant (±5.0 °F (2.8 °C)).
(i)
Installed facing upstream at a point where the dilution air and exhaust are well mixed (i.e., approximately 10 tunnel diameters downstream from the point where the exhaust enters the dilution tunnel).
(ii)
Sufficiently distant (radially) from the particulate probe so as to be free from the influence of any wakes or eddies produced by the particulate probe.
(iii)
Heated and insulated over the entire length to maintain a 235°±15 °F (113°±8 °C) wall temperature.
(13)
It is intended that the total hydrocarbon probe be free from cold spots (i.e., free from cold spots where the probe wall temperature is less than 220 °F.) This will be determined by a temperature sensor located on a section of the probe wall outside of the dilution tunnel. The temperature sensor shall be insulated from any heating elements on the probe. The sensor shall have an accuracy and precision of ±2 °F (1.1 °C).
(i)
At 235 °F±15 °F (113 °C±8 °C) immediately before the heated filter. This will be determined by a temperature sensor located immediately upstream of the filter. The sensor shall have an accuracy and precision of ±2 °F (1.1 °C).
(ii)
At 235 °F±15 °F (113 °C ±8 °C) immediately before the HFID. This will be determined by a temperature sensor located at the exit of the heated sample line. The sensor shall have an accuracy and precision of ±2 °F (1.1 °C).
(15)
It is intended that the dilute exhaust gas flowing in the hydrocarbon sample system be between 220 °F and 250 °F (105 °C and 121 °C).
(16)
For methanol-fueled vehicles, bag sampling procedures for the measurement of hydrocarbons as described in § 86.109 may be employed.
(d) Filters, particulate sampling.
(1)
Filter acceptance criteria. Valid diesel particulate net filter weights shall be accepted according to the following criteria:
(i)
During each phase of the UDDS, dilute exhaust will be simultaneously sampled by paired primary test and back-up test filters.
(ii)
The back-up filter holder shall be located 3 to 4 inches downstream of the primary filter holder.
(iii)
The net weight of particulate material collected on each primary test filter and each back-up test filter shall be determined by the procedure outlined in § 86.139.
(v)
If the ratio is greater than 0.95, then particulate emissions calculations are based on the net weight of the primary filter only.
(vi)
If the ratio is less than 0.95, then particulate emissions calculations are based on the combined net weights of the back-up test filter and the primary test filter.
(2)
The particulate filter must have a minimum 47 mm diameter (37 mm stain area). Larger diameter filters are also acceptable. (Larger diameter filters may be desirable in order to reduce the pressure drop across the filter when testing vehicles which produce large amounts of particulate.)
(3)
The recommended minimum loading on the primary 47 mm filter is 0.5 milligrams. Equivalent loadings (i.e., mass/stain area) are recommended for larger filters.
(4)
Fluorocarbon coated glass fiber filters or fluorocarbon-based (membrane) filters are required for particulate collection.