~14g-

Figure B81-1B are required to provide both gaseous and

particulate emissions sampling capabilities from a single system.

(4) 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.

(5) Other sampling systems ‘may be used if shown to yield

equivalent results and if approved in advance by the Administrator.

(b) Component description. The components necessary for

Diesel exhaust sampling shall meet the following requirements:

(1) |The PDP-CVS, Figure B81-1B 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 (51.7°C) or less.

(2) The transfer of heat from the vehicle exhaust gas shall
be minimized between the point where it leaves the vehicle tail-
pipe(s) and the point where it enters the dilution tunnel air-
stream, To accomplish this, a short length (not more than

12 feet (365 cm)) of 2.5 in (6.4 cm) I.D. smooth stainless steel


-35-

(1) Diurnal breathing losses resulting from daily temperature

changes, measured by the enclosure technique;

(2) Running losses from suspected sources (if indicated by
engineering analysis or vehicle inspection) resulting from a simulated

trip on a chassis dynamometer, measured by carbon traps; and

(3) Hot soak losses which result when the vehicle is parked
and the hot engine is turned off, measured by the enclosure

technique.

(e) Except in cases of component malfunction or failure,
all emission control systems installed on or incorporated in a
new motor vehicle shall be functioning during all procedures in
this subpart. Maintenance to correct component malfunction or

failure shall be authorized in accordance with §86.078-25.


-31-

§86.121-81 Hydrocarbon analyzer calibration.

[Each] FID hydrocarbon analyzer shall receive the following
initial and periodic calibration. [Each HFID] shall be operated

[at a temperature of 375° + 10°F (191° + 5.6°C)].

(a) Initial and periodic optimization of detector response.
Prior to its introduction into service and at least annually
thereafter [each] FID hydrocarbon analyzer shall be.adjusted for
optimum hydrocarbon response. Alternate methods yielding equiv-
alent results may be used, if approved in advance by the Admin-

istrator.

(1) Follow the manufacturer's instructions for instrument
startup and basic operating adjustment using the appropriate fuel

and zero-grade air.

(2) ‘ Optimize on the most common operating range. Introduce
into the analyzer, a propane in air mixture with a propane con-
centration equal to approximately 90 percent of the most common

operating range.

(3) Select an operating fuel flow rate that will give near
maximum response and least variation in response with minor fuel

flow variations.


-40-

that during field operation the vehicle receives additional
cooling, and that such additional cooling is needed to provide a
representative test, the fan capacity may be increased or additional

fans used if approved in advance by the Administrator.

(c) The vehicle speed as measured from the dynamometer
rolls shall be used. A speed vs. time recording, as evidence of
dynamometer test validity, shall be supplied on request of the

Administrator.

(d) Practice runs over the prescribed driving schedule may
be performed at test point, provided an emission sample is not
taken, for the purpose of finding the minimum throttle action to
maintain the proper speed-time relationship, or to permit sampling

system adjustment.

NOTE. - When using two-roll dynamometers a truer speed-time
trace may be obtained by minimizing the rocking of the vehicle in
the rolls. The rocking of the vehicle changes the tire rolling
radius on each roll. This rocking may be minimized by restraining
the vehicle horizontally (or nearly so) by using a cable and

winch.

(e) The drive wheel tires may be inflated up to a gauge
pressure of 45 psi (310 kPa) in order to prevent tire damage.
The drive wheel tire pressure shall be reported with the test

results.


~8-

The variable mixture flow rate is maintained at sonic velocity,
which is directly proportional to the square root of the gas

temperature, and is computed continuously. Since the pressure
and temperature are the same at both venturi inlets, the sample

volume is proportional to the total volume.

[ (4)] Other systems. Other sampling systems may be used if
shown to yield equivalent results, and if approved in advance by
the Administrator (e.g., a heat exchanger with the CFV-CVS; an
electronic flow integrator without a heat exchanger, with the

PDPCVS).

(b) Component description, PDP-CVS. The PDP-CVS, Figure

[B81-1A] consists of a dilution air filter and mixing assembly,
heat exchanger, positive displacement pump, sampling system, and
associated valves, pressure and temperature sensors. The PDP-CVS

shall conform to the following requirements:

(1) Static pressure variations at the tailpipe(s) of the
vehicle shall remain within + 5 inches of water (1.2 kPa) of the
static pressure variations measured during a dynamometer driving
cycle with no connection to the tailpipe(s). (Sampling systems
capable of maintaining the static pressure to within + 1 inch of
water (0.25 kPa) will be used by the Administrator if a written

request substantiates the need for this closer tolerance.)


-50-

[ (22)] Vehicles to be tested for evaporative emissions
will proceed according to §86.138. For all others this completes

the test sequence.


-48-

if (17)J Repeat the steps in paragraph (b)(2) through [(11)]
of.this section for the hot start test, except only one evacuated
sample bag is required for sampling exhaust gas and one for dilu-
tion air. The step in paragraph (b)[(8)] of this section shall

begin between 9 and 11 minutes after the end of the sample period

for the cold start test.

( (18) (1) Gasoline-fueled vehicles.] At the end of the
deceleration which is scheduled to occur at 505 seconds, simul-
taneously turn off gas flow measuring device No. 1 and postion
the sample selector valve to the "standby" position, (Engine

shutdown is not part of the hot start test sample period.)

[ (41) Diesel vehicles.

(1) At the end of the deceleration which is scheduled to
occur at 505 seconds, simultaneously turn off gas flow measuring
device No. 1 and both No. 1 Diesel hydrocarobn integrators, mark
both Diesel hydrocarbon recorder charts and start both No. 2
Diesel hydrocarbon integrators, and position the sample selector

valve to the "standby" position.

(2) Continue to operate the vehicle according to the Urban
Dynamometer Driving Schedule (§86.115) and continue to analyze
hydrocarbons on both HFIDs and to collect particulates on the

filter during the "stabilized" phase of the hot start test.


-54-

and dynamometer serial number. As an alternative to recording
the dynamometer serial number, a reference to a vehicle test cell
number may be used, with the advance approval of the Administra-

tor, provided the test cell records shown the pertinent information.

(h) All pertinent instrument information such as tuning -
gain - serial number - detector number - range. As an alternative,
a reference to a vehicle test cell number may be used, with the
advance approval of the Administrator, provided test cell calibra-

tion records show the pertinent instrument .information.

(i) Recorder charts: Identify zero, span, exhaust gas, and

humidity.

(j) Test cell barometric pressure, ambient temperature and

humidity.

NOTE. - A central laboratory barometer may be used: Provided,
That individual test cell barometric pressures are shown to be
within + 0.1 percent of the barometric pressure at the central

barometer location.

(k) Fuel temperatures, as prescribed.

(1) Pressure of the mixture of exhaust and dilution air

entering the CVS metering device, the pressure increase across


~58-

(b) The mass of particulate for either the cold start test

or the hot start test is determinéd as follows:

P
e P,
mF ‘nix, x ia - z (1 - 1/DF)]
; ep, bp

where:

(1) j = 1 or 2 depending on which test, the mass of particu-
late is being determined for (i.e., the cold start test, or the

hot start test).

(2) Vinx = total dilute exhaust volume in cubic feet per
test, corrected to standard conditions 528°R (293K) and 760 mm Hg
(101.3 kPa). Viy, is further defined in §86.144.

(3) Po = mass of particulate per test on the exhaust filter,

grams.

(4) PB = mass of particulate on the "background" filter,

grams.

(4) The background particulate level, P_, inside the dilu-

b?

tion air filter box at EPA is very low. PB will be assumed = 0,

and backgound particulate samples will not be taken with each

exhaust sample. It is recommended that background particulate


-46~
meter Driving Schedule (§86.115).

{ NOTE. During Diesel testing, adjust the flow rate through

the isokinetic sample probe to maintain a constant value within +
10 percent of isokinetic flow. Record the average temperature and
pressure at the gas meter inlet. If isokinetic flow cannot be
maintained because of high particulate loading on the filter, the
test shall be terminated. The test shall be rerun using a smaller
diameter probe, 0.5 in (1.27 cm) minimum. or larger diameter
filter, or both, and appropriate flow rate to maintain isokinetic

sampling. ]

[ (12)] At the end of the deceleration which is scheduled

to occur at 505 seconds, simultaneously switch the sample flows
from the "transient" bags to the "stabilized" bags, switch off
gas flow measuring device No. 1 (and [both No. 1] Diesel hydrocarbon
[integrators], mark [both] Diesel hydrocarbon recorder [charts])
and start gas flow measuring device No. 2 (and [both No. 2]
Diesel hydrocarbon [integrators]). Before the acceleration which
is scheduled to occur at 510 seconds, record the measured roll or
shaft revolutions and reset the counter or switch to a second
counter. As soon as possible transfer the "transient" exhaust
and dilution air samples to the analytical system and process the
samples according to §86.140 obtaining a stabilized reading of

the exhaust sample on all analyzers within 20 minutes of the end


-18-

(i) installed facing upstream at a point where the dilution
air and exhaust are well mixed (i.e., approximately 10 tunnel
diameters downstream of 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 to maintain a 375° + 10°F (191° + 5.6°C) sample

temperature.

(iv) 0.18 in. (0.476 cm) minimum inside diameter.

(v) free from cold spots (i.e., free from spots where the

probe wall temperature is less than 365°F).
(11) The dry gas meter shall be located sufficiently far from
the tunnel so that the inlet gas temperature remains constant

(+ 5°F (2.8°C)) and near room temperature.

(c) Filters, particulate sampling.

(1) Filters used for particulate collection must have a
collection efficiency of 99.9 percent or greater. The collection

efficiency shall be determined by the procedure specified in ASTM


~36-

§86.132-81 Vehicle preconditioning.

(a) The vehicle shall be moved to the’test area and the

following operations performed:

(1) The fuel tank(s) shall be drained through the provided
fuel tank(s) drain(s) and filled to the prescribed "tank fuel
volume" with the specified test fuel, §86.113. For the above
operations the evaporative emission control system shall neither

be abnormally purged nor abnormally loaded.

(2) Within one hour of being fueled the vehicle shall be
placed, either by being driven or pushed, on a dynamometer and
operated through one Urban Dynamometer Driving Schedule test pro-
cedure, see §86.115 and Appendix I. A gasoline-fueled test

vehicle may not be used to set dynamometer horsepower.

(3) For those unusual circumstances where additional precon-
ditioning is desired by the manufacturer, such preconditioning
may be allowed with the advance approval of the Administrator.
The Administrator may also choose to conduct or require the
conduct of additional preconditioning to insure that the evapor-
ative emission control system is stabilized [in the case of
gasoline engines, or to insure that the exhaust system is stabilized
in the case of Diesel engines.] The additional preconditioning

shall consist of an initial one hour minimum soak and, one, two,


*

Section

86.115-78
86.116-78
86.116-81

86.117-78

86.118-78
86.119-78
86.120-78

{86.120-81}

86.121-78
86.121-81
86.122-78

86.123-78

86.124-78
86.125-78
86.126-78
86.127-78
86.127-81
86.128-78

86.129-78

86.129-79

86.130-78

86.131-78

EPA dynamometer driving schedules.
Calibrations; frequency and overview.
Calibrations; frequency and overview.

Evaporative emission enclosure
calibrations.

Dynamometer calibration.
CVS calibration.
Reserved.

Gas meter calibration; particulate
measurement.

Hydrocarbon analyzer calibration.
Hydrocarbon analyzer calibration.
Carbon monoxide analyzer calibration.

Oxides of nitrogen analyzer
calibration.

Carbon dioxide analyzer calibration.
Reserved.

Calibration of other equipment.

Test procedures; overview.

Test procedures; overview.
Transmissions.

Road load power and inertia weight
determination.

Road load power and inertia weight
determination.

Test sequence; general requirements.

Vehicle preparation.

27

29

31

33


~29-

[§86. 120-81 Gas meter calibration, particulate measurement.

Sampling for particulate emissions requires the use of a gas
meter to measure flow through the particulate filter. This meter

shall receive initial and periodic calibration as follows:

(a) Install a standard air flow measurement instrument (such
as a laminar flow element) upstream of the gas meter. This stan-
dard instrument shall measure SCFM air flow with an accuracy of
+1 percent. Standard conditions are defined as 68°F (293°K) and
760 mm Hg (101.3 kPa). A critical flow orifice or a laminar flow

element is recommended as the standard instrument.

(b) Flow air through the calibration system at the isokin-
etic sampling flow rate of the system and at the back pressure

which occurs: during the sampling procedure.

(c) When the temperature and pressure in the system have
stabilized, measure the gas meter indicated volume over a time
period of at least 5 minutes and until a flow volume of at least
+1 percent accuracy can be determined by the standard instrument.
Record the stabilized air temperature and pressure upstream of

the gas meter and as required for the standard instrument.

(d) Calculate SCFM as measured by both the standard instru-

ment and the gas meter.


-15-

tubing from the tailpipe to the dilution tunnel is required. Short

.sections of flexible tubing at connection points are allowed.
(3) The dilution tunnel shall be:

(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 isokinetic particulate probe and the heated HC sample

probe).

(ii) large enough in diameter to permit isokinetic sampling

through the probe as required in paragraph (b)(5) of this section.

(iii) constructed of a material which does not react with the

exhaust components.

(4) The temperature of the diluted exhaust stream inside of
the dilution tunnel shall be sufficient to prevent water conden-
sation, However, the sample zone dilute exhaust temperature shall

not exceed 125°F (51.7°C) at any time during the test.
(5) The particulate sample probe shall be:

(i) installed facing upstream at a point where the dilution

air and exhaust are well mixed (i.e., on the tunnel centerline,


-21-

§86.111-81 Exhaust gas analytical system.

(a) Schematic drawings. Figure B78-3 is a schematic drawing
of the exhaust gas analytical system. The schematic of the
hydrocarbon analysis [trains] for Diesel vehicles [are] shown as
part of Figure [B81-1B]. Since various configurations can produce
accurate results, exact conformance with either drawing 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.

(b) Major component description. The analytical system,

Figure B78-3, consists of a flame ionization detector (FID) for
the determination of hydrocarbons, nondispersive infared analyzers
(NDIR) for the determination of carbon monoxide and carbon dioxide
and a chemiluminescence analyzer (CL) for the determination of
oxides of nitrogen. [Two] heated flame ionization [detectors]
(HFID) [are] used for the continuous determination of hydrocarbons
from Diesel fueled vehicles, Figure [B81-1B]. The exhaust gas

analytical system shall conform to the following requirements:

(1) The CL requires that the nitrogen dioxide present in
the sample be converted to nitric oxide before analysis. Other
types of analyzers may be used if shown to yield equivalent

results and if approved in advance by the Administrator.


-1)-

(7) The flow rate through the particulate probe shall be:

(1) within 10 percent of isokinetic at all times throughout
the test as determined by assuming uniform flow radially across

the dilution tunnel; and

(ii) at least 0.35 CFM (0.16 1/s).

(8) The particulate sample flow shall be heated to a temp-
erature of 375° + 10°F (191° + 5.6°C) shortly (within two feet
(61 cm)) after the particulate has been collected. A portion of
this heated sample is extracted for HFID hydrocarbon analysis, and
then is returned to the main particulate sample flow before any
flow measurements are taken. The main particulate sample flow

need not be heated beyond the point where this hydrocarbon sample
is taken.

(9) The particulate sample pump shall be:

(i) heated so as to maintain the sample gas temperature at

375 + 10°F (191 + 5.6°C).

(ii) of sufficient capacity to maintain isokinetic flow into

the probe throughout the test.

(10) The total hydrocarbon probe shalltbe:


-30-

(e) Repeat the procedure of paragraph (b). through (a) above
using flow rates which are 10 percent above the isokinetic flowrate

and 10 percent below the isokinetic flowrate.

(£) If the SCFM measured by the gas meter differs by more
than + 1 percent from the standard measurement at any of the
three measured flow rates, than a correction shall be made by

either of the following two methods:

(1) Mechanically adjust the gas meter so that it agrees
within 1 percent of the standard measurement at the three specified

flowrates, or

(2) Develop a calibration curve for the gas meter from the
three calibration points. A correction factor for the gas meter,
at any flow rate which differs by more than 1 percent from the

standard instrument is defined as:

K= SCFM as measured by standard instrument ]
m SCFM as measured by gas meter .



-12-

. AABIENT AR
aa
.
ute a
mune
1 |

eycronie
SEPARATOR

mows |

Figure B78-2 - rama
Exhaust Gas Sampling System (CFV-CVS)

(See Figure B78-3 For Symbol Legend)


-56-

(1) Pressure and temperature of the dilute exhaust mixture
(and dilution air if sampled) at the inlet to the gas meter used

for particulate sampling.

(2) The maximum temperature of the dilute exhaust mixture
inside the dilution tunnel near‘the inlet of the isokinetic

probe.

(3) Dry gas meter readings at the start of each sample per-

iod, and at the end of each sample period.

(4) The stabilized pre-test weight and post test weight of

each particulate sample filter.

(5) The temperature and humidity of the ambient air in

which the particulate filters were stabilized. ]


§86.105-81 Introduction; structure of subpart.

(a) This subpart describes the equipment required and the’
procedures to follow in order to perform [gaseous] exhaust, [Diesel
particulate,] and evaporative emission tests on light-duty vehi-
cles and light-duty trucks. Subpart A sets forth the testing
requirements and test intervals necessary to comply with EPA

certification procedures.

(b) Three topics are addressed in this subpart. Sections
86.106 through 86.115 set forth the specifications and equipment
requirements; §§86.116 through 86.126 discuss calibration methods
and frequency; test procedures and data requirements are listed

(in approximate order of performance) in §§86.127 through 86.145.


-27-

§86.116-81 Calibrations, frequency and overview.

(a) Calibrations shall be performed as specified in §§86.117

through 86.126.

(b) At least yearly or after any maintenance which could
alter background emission levels, enclosure background emission

measurements shall be performed.

(c) At least monthly or after any maintenance which could
alter calibration, the following calibrations and checks shall be

performed:

(1) Calibrate the hydrocarbon analyzers (both evaporative
and exhaust instruments), carbon dioxide analyzer, carbon monoxide

analyzer, and oxides of nitrogen analyzer.

(2) Calibrate the dynamometer. If the dynamometer receives
a weekly performance check (and remains within calibration) the

monthly calibration need not be performed.

(3) Perform a hydrocarbon retention check and calibration

on the evaporative emission enclosure.

[ (4) Calibrate the gas meter(s) used for providing total

flow measurement for particulate sampling. ]


~24-

For Diesel HC Analysis (OPEN TO ATMOSPHERE
XY See Figure [B81-1B]
ti
TRO
2 as
H =
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MCE | FIGURE 878-2 EXHAUST GAS ANALYTICAL SYSTEM



-l-

[§86.081-2 Definitions.

The following definitions apply begining with the 1981 model

year. §§86.077-2 and 86.078-2 remain in effect.

"Isokinetic" means that the velocity of a gas in a sample
stream is the same as the free stream velocity of the gas from

which the sample is collected.

"Particulate" means any material (excluding condensed water)
collected by filtering a sample of diluted exhaust. Both the
filter and the exhaust stream from which the sample is taken must

be at or below a temperature of 125°F (51.7°C). ]


*

Section

86.132-78
86.132-81
86.133-78
86.134-78
86.135-78
86.135-81
86.136-78
86.137-78

86.137-81

86.138-78
86.139-78

{86.139-81}

86.140-78

86.141-78
86.142-78
86.142-81
86.143-78
86.144-78
86.145-78

{86.145-81}

= sections contained in this document.

Vehicle preconditioning.
Vehicle preconditioning.
Diurnal breathing loss test.
Running loss test.

Dynamometer procedure.
Dynamometer procedure.

Engine starting and restarting.
Dynamometer test runs.

Dynamometer test run; gaseous
and particulate emissions.

Hot ‘soak test.
Reserved.

Diesel particulate filter handling
and weighing.

Exhaust sample analysis; [gaseous
emissions. ]

Reserved.
Records required.

Records required.

Calculations; evaporative emissions.

Calculations; gaseous exhaust emissions.

Reserved.

Calculations; particulate emissions.

see 42 FR 32906 (June 28, 1977).

Page

36

38

42

51

53

57

For other sections,


-13-

[§86.110-81 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 light-duty

- Diesel vehicles. This system utilizes the CVS concept (described
in §86.109-81) of measuring mass emissions. The mass of gaseous
emissions is determined from the sample concentration and total-
ized flow over the test period. The mass of particulate emissions
is determined from a proportional mass sample collected on a
filter and from the totalized flow over the test period. General

requirements are as follows:

qd) This sampling system requires the use of a PDP-CVS
connected to a dilution tunnel. Figure B81-1B is a schematic

drawing of the recommended system.

(2) Diesel vehicles require two heated flame ionization
detector (HFID) samples for hydrocarbon analysis. The first HFID
sample must be taken directly from the diluted exhaust stream
through a heated probe which must be installed in the dilution
tunnel. The second HFID sample must be taken (through heated lines)
from the particulate sample flow after the particulate has been

collected by the unheated filter.

(3) Bag, HFID and particulate sampling capabilities as shown in


-3-

§86.102 Definitions

The definitions in §§86.077-2, 86.078-2 [and 86.081-2] apply

to this subpart.


~-19-

D-2986.

(2) 47 mm nominal diameter is sufficiently large for most
Diesel powered vehicles. Larger diameter filters are also accep-—
table. (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) Glass fiber filters are recommended for particulate
collection because of their characteristic low pressure drop.
However, glass fiber filters have two characteristic disadvantages:
they are hydroscopic; and they are very fragile. Specific steps
(§86.112-81 and §86.139-81) must be taken to be sure that neither
of these two disadvantages affect the measured mass of particulate.
Fluorocarbon coated glass fiber filters are less fragile and less
hydroscopic than glass fiber filters, but are considered to have
a relatively high pressure loss. However, these filters may be
used without prior EPA approval if shown to yield results

equivalent to those of glass fiber filters.]


Draft
Recommended Practice

for
Measurement of Gaseous and Particulate Emissions
from

Light-Duty Diesel Vehicles

March, 1978


~42-

§86.137-81 Dynamometer test run, gaseous [and particulate]

emissions.

[(a) General. ]

{ (1) Gasoline-fueled vehicles.] The vehicle shall be allowed
to stand with the engine turned off for a period of not less than
12 hours or more than 36 hours before the cold start exhaust
emission test. The cold start exhaust test shall follow the
diurnal breathing loss test by not more than one hour. The
vehicle shall be stored prior to the emission test in such a
manner that precipitation (e.g., rain or dew) does not occur on

the vehicle. The complete dynamometer test consists of a cold
start drive of 7.5 miles (12.1 km) and simulates a hot start

drive of 7.5 miles (12.1 km). The vehicle is allowed to stand on
the dynamometer during the 10 minute time period between the cold
and hot start tests. The cold start test is divided into two
periods. The first period, representing the cold start "transient"
phase, terminates at the end of the deceleration which is scheduled
to occur at 505 seconds of the driving schedule. The second
period, representing the "stabilizied" phase, consists of the
remainder of the driving schedule including engine shutdow. The
hot start test similarly consists of two periods. The first
period, representing the hot start "transient" phase, terminates

at the same point in the driving schedule as the first period of

the cold start test. The second period of the hot start test,


~6-

fueled vehicles are either tested for evaporative emissions or
undergo a diurnal heat build, Diesel vehicles are excluded from

this requirement. Equipment necessary and specifications appear

in §§86.108 through 86.114.

(3) Fuel, analytical gas, and driving schedule specifications.

Fuel specifications for exhaust and evaporative emissions testing
and for mileage accumulation for gasoline-fueled and Diesel
vehicles are specified in §86.113. Analytical gases are specified

in §86.114.

The EPA Urban Dynamometer Driving Schedule (UDDS) for use in
(both gasoline-fueled and Diesel exhaust emissions tests] is

specified in §86.115 and Appendix I.


-5-

§86. 106-81 Equipment required; overview.

(a) This subpart contains procedures for both exhaust and
evaporative emissions tests on Diesel or gasoline-fueled light-
duty vehicles and light-duty trucks. Certain items of equipment
are not necessary for a particular test, e.g., evaporative enclo-
sure when testing Diesel vehicles. Equipment required and

specifications are as follows:

(1) Evaporative emission tests, gasoline-fueled vehicles.

The evaporative emission test is closely related to and connected
with the exhaust emission test, All vehicles tested for evapora-
tive emissions must be tested for exhaust emissions. Further,
unless the evaporative emission test is waived by the. Administra-
tor under§86.078-26, all gasoline-fueled vehicles must undergo both
tests. (Diesel vehicles are excluded from the evaporative emis-

sion standard.) Section 86.107 specifies the necessary equipment.

(2) Exhaust emission tests. All vehicles subject to this
subpart are tested for exhaust emissions. [The exhaust from gaso-
line-fueled vehicles is tested for gaseous emissions only, using the
CVS concept (§86.109-81). The exhaust from Diesel vehicles is
tested for gaseous and particulate emissions. Diesel testing also
utilizes the CVS concept of measuring emissions, but requires that
a PDP CVS be used, and that it be connected to a dilution tunnel in

order to sample particulate emissions (§86.110-81).] All gasoline-


-55-

the device, and the temperature at the inlet.’ The temperature

may be recorded continuously or digitally to determine temperature

variations.

(m) The number of revolutions of the positive displacement
pump accumulated during each test phase while exhaust samples are
being collected. The number of standard cubic feet metered by a
critical flow venturi during each test phase would be the equiva-

lent record for a CFV-CVS.
(n) The humidity of the dilution air.

NOTE. - If conditioning columns are not used (see §86.122
and §86.144) this measurement can be deleted. If the conditioning
columns are used and the dilution air is taken from the test

cell, the ambient humidity can be used for this measurement.

(0) Temperature [of the gas in both heated sample lines and
the temperature of the control system of both heated hydrocarbon

detectors] (for Diesel vehicles only).

(p) The driving distance for each of the three [(four for
Diesels)] phases of the test, calculated from the measured roll

or shaft revolution.

C (a) Additional ‘required ‘records ‘for Diesel vehicles.



-38-

§86.135-81 Dynamometer procedure.
{ (a) Dynamometer cycles. ]
t @ Gasoline-fueléd vehicles. ] The dynamometer run consists

of two tests, a "cold" start test after a minimum 12-hour and a
maximum 36 hour soak according to the provisions of §86.132 and
§86.133 and a "hot" start test following the "cold" start by 10
minutes. Engine startup (with all accessories turned off), oper-
ation over the driving schedule, and engine shutdown make a com-
plete cold start test. Engine startup and operation over the
first 505 seconds of the driving schedule complete the hot start
test. The exhaust emissions are diluted with ambient air and a
continuously proportional sample is collected for analysis during
each phase. The composite samples collected in bags are analyzed
for hydrocarbons, carbon monoxide, carbon dioxide, and oxides of
nitrogen. A parallel sample of the dilution air is similarly

analyzed for hydrocarbon, carbon monoxide, and oxides of nitrogen.

{ (2) Diesel vehicles. The dynamometer run consists of two
tests, a "cold" start test after a minimum 12 hour soak according
to the provisions of §86.132 and §86.133 and a "hot" start test
following the "cold" start by 10 minutes. Engine startup (with
all accessories turned off), operation over the UDDS and engine
shutdown make a complete cold start test. Engine startup,

repeat operation over the complete UDDS and engine


-26-

(1) The microgram balance used to determine the weights of all
filters shall have a precision (standard deviation) and a read-

ability (micrometer) of one microgram.

(2) The microgram balance used to determine the weights of

all filters shall have a minimum weighing range of one gram. ]


-43-

"stabilized" phase, is assumed to be identical to the second
period of the cold start test. Therefore, the hot start test

terminates after the first period (505 seconds) is run.

{[ (2) Diésel vehicles. The vehicle shall be allowed to stand
with the engine turned off for a period of not less than 12 hours
or more than 36 hours before the cold start exhaust emission test.
The vehicle shall be stored prior to the emission test in such a
manner that precipitation (e.g., rain or dew) does not occur on

the vehicle. The complete dynamometer test consists of a cold
start drive of 7.5 miles (12.1 km) and a hot start drive of 7.5
miles (12.1 km). The vehicle is allowed to stand on the dynamome-
ter during the 10 minute time period between the cold and hot start
tests. The cold start test is divided into two periods. The first
period, representing the cold start "transient" phase, terminates
at the end of the deceleration which is scheduled to occur at 505
second of the driving schedule. The second period, representing
the "stabilized" phase, consists of the remainder of the driving
schedule including engine shutdown, The hot start test similarly
consists of two periods. The first period, representing the hot
start "transient" phase, terminates at the same point in the -
driving schedule as the first period of the cold start test. The
second period of the hot start test, "stabilized" phase, is

identical to the second period of the cold start test. ]

(b) The following steps shall be taken for each test:


-25-

[§86.112-81 Weighing room and microgram balance specifica-

tions.

(a) Ambient conditions.

(1) Temperature. The temperature of the room in which the
particulate filters are conditioned and weighed shall be maintained
to within + 5°F (+ 2.8°C) of a set point between 68°F (20°C) and

86°F (30°C) during all filter conditioning and filter weighing.

(2) Humidity. The relative humidity of the room in which
the particulate filters are conditioned and weighted shall be
maintained to within + 5 percent of a set point between 40 and 50

percent during all filter conditioning and filter weighing.

(3) The room air shall be free from any ambient contaminates
(such as dust) that would settle on the particulate filters
during their conditioning. It is recommended that two reference
filters remain in the weighing room at all times, and that these
filters be weighed daily. If the weight of these reference
filters changes by more than + 0.015 percent (typically + 20 micro-
grams for a 47 mm glass fiber filter) in any twenty-four hour
period, then all filters in the process of being conditioned

should be discarded, and any tests repeated.

(b) ‘Microgram balance spécifications.



§86.101 General applicability.

(a) The provisions of this subpart are applicable to 1977
and later model year new light-duty vehicles and light-duty

trucks.

{(1) Sections ending in "-81" apply for 1981 and later model

years.)

(2) Sections §86.101 through §86.145-78 apply for 1978 and

later model years.

(3) Sections §86.177-4 through §86.117-23 apply for the

1977 model year only.

(b) Provisions of this’ subpart apply to tests performed by

both the Administrator and motor vehicle manufacturers.


-16-

approximately 10 tunnel diameters downstream of the point where

the exhaust enters the dilution tunnel).

(ii) sufficiently distant (radially) from the total hydro-
carbon probe so as to be free from the influence of any wakes

or eddies produced by the total hydrocarbon probe.

(iii) sized to permit isokinetic sampling.

(iv) 0.5 in. (1.27 cm) minimum inside diameter.

(v) 5-10 probe diameters from sampling tip to the filter

holder which shall be located inside of the tunnel or immediately

outside of the tunnel.

(vi) free from sharp bends.

(6) The flow velocity near the particulate probe tip shall

be determined by:

(i) measurement; or

(ii) by assuming that it is 10 percent greater than the
average velocity of the diluted exhaust stream in the tunnel.
The average velocity is defined as the actual volumetric flow

divided by the cross sectional area of the dilution tunnel.


-53-

§86.142-81 Records required.

The following information shall be recorded with respect to

each test:

(a)

(b)

(c)

(a)

Test number.

System of device tested (brief description).

Date and time of day for each part of the test schedule.

Instrument operator.

Driver or operator.

(£)

Vehicle: ID number, manufacturer, model year, standards,

engine family, evaporative emissions family, basic engine descrip-

tion (including displacement, number of cylinders, and catalysts

usage), fuel system (including number of curburetors, number of

carburetor barrels, fuel injection type and fuel tank(s) capacity

and location), engine code, gross vehicle weight rating, inertia

weight class, actual curb weight at zero. miles, actual road load

at 50 mph, transmission configuration, rpm and drive wheel tire

pressure, as applicable.

(g)

Indicated road load power absorption at 50 mph (80 kph)


-60-

(iv) P ip = pressure elevation above ambient measured at the
inlet to the dilute exhaust sample gas meter, mm Hg. For most

gas meters with unrestricted discharge P. p is negligible and can

4

be assumed = 0.

(v) Tip = average temperature of the dilute exhaust sample

at the inlet to the gas meter, °R.

(7) Yop = total volume of the background sample, cubic feet

at standard conditions. Wy, is not required if PB is assumed =

0.) It is calculated using the following formula:

v= Kup * Yap * Char + Ps) x 528

b Ty * 760
where:

(4) Ko = background gas meter correction factor determined
in §85.120.

(ii) Vp = actual backgound sample volume, cubic feet.

(i1i) P,

bar barometric pressure, mm Hg.

(iv) Pip = pressure elevation above ambient measured at the
inlet to the background gas meter, mm Hg. For most gas meters

with unrestricted discharge PY is negligible and can be assumed = 0.


-33-

§86.127-81 Test procedures; overview.

The procedures described in this and subsequent sections are
used to determine the conformity of vehicles with the standards
set forth in Subpart A for light-duty vehicles and light-duty

trucks.

(a) The overall test consists of prescribed sequences of
fueling, parking and operating conditions. [Vehicles are tested

for any or all of the following emissions:

(i) gaseous exhaust HC, CO, NOx, cO,.

(4i) particulates (Diesels only).

(ii4) evaporative HC. ]

The evaporative portion of the test procedure occurs before and
after the exhaust emission test, and in some cases, during the

exhaust emission test.

(b) The [gasoline~fueled] exhaust emission test is designed
to determine hydrocarbon, carbon monoxide, and oxides of nitrogen
mass emissions while simulating an average trip in an urban area
of 7.5 miles (12.1 km). The test consists of engine startups and

vehicle operation on a chassis dynamometer, through a specified


-34-

driving schedule. A proportional part of:.the diluted exhaust is
collected continuously for subsequent analysis, using a constant

volume (variable dilution) sampler.

[ (c) The Diesel exhaust emission test is designed to determine
particulate and gaseous mass emissions during a test similar to
the test in §86.127-81(b). Dilute exhaust is continuously analyzed
for total hydrocarbons, and for hydrocarbon retention by particulate
material (computed from the difference in integrated responses be-
tween the two separate HFID systems). The other gaseous emissions,
co, co, and NOx are collected continuously for analysis as in
§86.127-81(b). Simultaneous with the gaseous exhaust collection
and analysis, particulates from a proportional part of the diluted
- exhaust are collected continuously on a filter. The mass of parti-
culate is determined by the procedure described in §86.139-81. This
testing requires a dilution tunnel as well as the constant volume

sampler. ]

(d) The evaporative emission test (gasoline-fueled vehicles

only) is designed to determine hydrocarbon evaporative emissions
as a consequence ‘of diurnal temperature fluctuation, urban driving,
and hot soaks during parking. It is associated with a series of
events representative of a motor vehicle's operation, which result
in hydrocarbon vapor losses. The test procedure is designed to

measure:


-49-

(3) Turn the engine off 2 seconds after the end of the last

deceleration (at 1,369 seconds)

(4) Five seconds after the engine stops running, simul~
taneously turn off both No. 2 Diesel hydrocarbon integrators,
mark both hydrocarbon recorder charts, and turn off the parti-
culate sample pump. Record the measured roll or shaft revolu-
tions, dry gas meter reading, and re-set the counter. Remove the
second particulate sample filter from the holder, and place in a

clean covered glass petri dish.

(5) As soon as possible, and in no case longer than 20 min-
utes after the end of this portion of the test transfer the two

particulate filters to the weighing room for post-test conditioning. ]

[ (19) ] As soon as possible transfer the hot start "tran-
sient" exhaust and dilution air samples to the analytical system
and process the samples according to §86.140 obtaining a stabil-
ized reading of the exhaust sample on all analyzers within 20
minutes of the end of the sample [bag] collection phase of the

test.

[ (20) ] Disconnect the exhaust tube from the vehicle

tailpipe(s) and drive the vehicle from dynamometer.

[ (21)] The CVS may be turned off, if desired.


-22-

(2) The carbon monoxide (NDIR) analyzer may require a
sample conditioning column containing CaSO, , or indicating silica
gel to remove water vapor and containing ascarite to remove

carbon dioxide from the CO analysis stream.

(i) If CO instruments which are essentially free of co, and
water vapor interference are used, the use of the conditioning

column may be deleted, see §§86.122 and 86.144.

(ii) A CO instrument will be considered to be essentially
free of co, and water vapor interference if its response to a
mixture of 3 percent co, in Ny which has been bubbled through
water at room temperature produces an equivalent CO response, as
measured on the most sensitive CO range, which is less than 1
percent of full scale CO concentration on ranges above 300 ppm
full scale or less than 3 ppm on ranges below 300 ppm full scale,

see §86.122.

(3) For Diesel vehicles [two] continous samples shall be
measured using [two] heated analyzer [trains] as show in Figure
[B81-1B]. [Both of these trains] shall include a heated continuous
sampling line, a heated particulate filter [(total HC system
only)], and a heated hydrocarbon instrument (HFID) complete with

heated pump, filter and flow control system.

(i) The response time of [these instruments] shall be less

than 1.5 seconds for 90 percent of full scale response.


~52-

lost during handling, and especially when removing the filter
from the filter holder. This material loss will result in an
erroneous (low) measurement of the particulate mass. These

handling losses must be minimized.

(ii) Should the sample on the filter contact the petri dish

or any other surface, the test is void and must be re-run.]


-6l-

(v) T,, =.average temperature of the background sample at

ib
the inlet to the gas meter, °R.

(8) DF = dilution factor. (DF is not required if PL is

assumed = 0.) DF is defined in §86.144-78.

NOTE. - For the second stabilized bag, the same DF which

applied to the first stabilized bag may be used. J


*

Section
{86.081-2}
86.101
86.102
86.103
86.104-78
86.105-78
86.105-81
86.106-78
86. 106-81

86.107-78

86.108-78
86.109-78

86.109-81

86.110-78

{86.110-81}

86.111-78
86.111-81
86.112-78
{86.112-81}
86.113-78
86.114-78

86.114-79

Table of Contents

Definitions.
Applicability.
Definitions.
Abbreviations.

Section numbering; construction.

Introduction; structure of Subpart.

Introduction; structure of Subpart.

Equipment required; overview.

Equipment required; overview.

Sampling and analytical system;

evaporative emissions.
Dynamometer.
Exhaust gas sampling system.

Exhaust gas sampling system;
gasoline-fueled vehicles.

Reserved.

Exhaust gas sampling system;
Diesel vehicles.

Exhaust gas analytical system.
Exhaust gas analytical system.
Reserved.

Particulate analytical system.
Fuel specifications.
Analytical gases.

Analytical gases.

13

21

25


-41-

(£) If the dynamometer has not been operated during the 2
hour period immediately preceding the test it shall be warmed up
for 15 minutes by operating at 30 mph (48 kph) using a non-test

vehicle or as recommended by the dynamometer manufacturer.

(g) If the dynamometer horsepower must be adjusted manually,
it shall be set within 1 hour prior to the exhaust emissions test
phase. The test vehicle shall not be used to make this adjust-
ment. Dynamometers using automatic control of preselectable
power settings may be set anytime prior to the beginning of the

emissions test.

(h) The driving distance as measured by counting the number
of dynamometer roll or shaft revolutions, shall be determined for
the transient cold start, stabilized cold start, and transient
hot start [(and stabilized hot start for Diesel vehicles)] phases
of the test. The revolutions shall be measured on the same roll

or shaft used for measuring the vehicle's speed.


~39-

shutdown complete the hot start test. The exhaust emissions are
diluted with ambient air in the dilution tunnel as shown in
Figure B81-1B. Two isokinetic particulate samples are collected
on filters for weighing; one sample is collected during the
"cold" start test, and another sample is collected during the
“hot" start test. Continuous proportional samples are collected
(according to the provisions of §86.110-81) for gaseous emissions
analysis (according to the provisions of §86.111-81) during the
"cold" start test and the first 505 seconds of the "hot" start
test. The composite sample collected in bags are analyzed for
carbon monoxide, carbon dioxide, and oxides of nitrogen. Hydro-
carbons are sampled and analyzed continuously according to the
provisions of §§86.110-81. Parallel samples of the dilution air
are similarly analyzed for hydrocarbon, carbon monoxide, and

oxides of nitrogen. ]

(b) During dynamometer operation, a fixed speed cooling fan
shall be positioned so as to direct cooling air to the vehicle in
an appropriate manner with the engine compartment cover open. In
the case of vehicles with front engine compartments, the fan
shall be squarely positioned within 12 inches of the vehicle. In
the case of vehicles with rear engine compartments (or if special
designs make the above impractical), the cooling fan shall be
placed in a position to provide sufficient air to maintain
vehicle cooling. The fan capacity shall normally not exceed

5,300 cfm (2.50 m/s). If, however, the manufacturer can show


(2) The gas mixture temperature, measured at a point immedi-
ately ahead of the positive displacement pump, shall be within +
10°F (5.6°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 + 10°F (5.6°C)
during the entire test. The temperature measuring system shall

have an accuracy and precision of + 2°F (1.1°C).

(3) The pressure gauges shall have an accuracy and precision

of + 3 mm Hg (0.4 kPa).
(4) The flow capacity of the CVS shall be large enough to
eliminate water condensation in the system (300 to 350 cfm, 0.140

to 0.165 m/s, is sufficient for most vehicles).

(5) Sample collection bags for dilution air and exhaust

samples shall be sufficient size so as not to impede sample flow.

(c) Component description, CFV-CVS. The CFV-CVS, Figure

B78-2, consists of a dilution air filter and mixing assembly,
cyclone particulate separator, sampling venturi, critical flow
venturi, sampling system and assorted valves, pressure and temper-
ature sensors. The CFV-CVS shall conform to the following require-

ments:

(1) Static pressure’ variations at the tailpipe(s) of the


-51-

[§86. 139-81 Diesel particulate filter handling and weighing.

(a) Twenty-four hours before the test, place each filter in
an open, but protected, glass petri dish in the weighing room
which meets the humidity and temperature specifications of

§86.112-81.

(b) At the end of the 24 hour period, weigh the filter on a
balance having a precision of one microgram. Record this weight.

This ‘reading is the tare weight.

(c) The filter shall then be stored in a covered glass

petri dish,

(a) If the filter is not used within 4 hours of the weighing,

it shall be re-weighed.

(e) After the test, and after the sample filter is returned
to the weighing room, condition it for a 24 hour period. Then
weigh a second time. This last reading is the gross weight of

the filter. Record this weight.

(£) The net weight (Pe) is the gross weight minus the tare

weight.

NOTE. - (i) Filter material from glass fiber filters can be


-57-
[§86. 145-81 Calculations; particulate emissions.

(a) The final reported test results for the mass of parti-

culate a) in grams/mile shall be computed as follows:

Mie 0-43.04, / ee +D,)) + 0.5708, / One +D,,))

=
a

Mass of particulate determined from the cold start

M = Mass of particulate determined from the hot start

test.

Dot

the measured driving distance from the "transient"

phase of the cold start test in miles.

Dog = The measured driving distance from the "stabilized"

phase of the cold start test, in miles.

D,, + = The measured driving distance from the "transient"

ht
phase of the hot start test, in miles.

Dig 7 The measured driving distance from the "stabilized"

phase of the hot start test, in miles.


AMBIENT
Ayz INLET
tt
Vv () A
>
; qj

| TO TALUTICN \
Ae SAMPLING

FIGURE B81-1A : .
-EXYAUST GAS |
: “Trectane



procedure requires a dilution tunnel and positive displacement pump
constant volume sampler (§86.110-81). Particulate samples are
withdrawn from the tunnel and collected on a filter media operating
at a maximum temperature of 125°F (51.7°C) (§86.110-81). Total
hydrocarbons are measured continuously through a heated probe in
the dilution tunnel with the overall sampling system held to

375° + 10°F (191° + 5.6°C) (§86.110-81). CO, C04, and NOx are
collected in the constant volume sampler bag as presently defined

in the Federal Register (§86.110-81 ‘and §86.135-81).

Two particulate samples are taken. A cold start sample is col-
lected over the combined cold transient and cold stabilized por-
tions of the driving cycle, comparable to Bag #1 and Bag #2. A
hot start sample is collected over the hot transient and hot
stabilized portions of the cycle and requires that the hot stabi-
lized (Bag #4) dynamometer operation be added to the present test
procedure (§86.135-81). Filters are weighed on a microgram

balance in a controlled ambient weighing room (§86.112-81).

A heated hydrocarbon analysis is specified in the sample stream
behind the particulate filter (§86.110-81). The difference be-
tween the amount of hydrocarbon measured at this point and the
total hydrocarbon measured in the dilution tunnel is an indication
of the total organics retained by the materials collected on the

filter.


-32-

(4) To determine the optimum air flow, use the fuel flow

setting determined above and vary air flow.

(5) After the optimum flow rates have been determined, they

are recorded for future reference.

(b) Initial and periodic calibration. Prior to its intro-
duction into service and monthly thereafter the FID hydrocarbon
analyzer shall be calibrated on all normally used instrument

ranges. Use the same flow rate as when analyzing sample.

(1) Adjust analyzer to optimize performance.

(2) Zero the hydrocarbon analyzer with zero-grade air.

(3) Calibrate on each normally used operating range with
propane in air calibration gases having nominal concentrations of
15, 30 , 45, 60, 75, and 90 percent of that range. For each
range calibrated, if the deviation from a least squares best-fit
straight line is 2 percent or less of the value at each data
point, concentration values may be calculated by use of single
calibration factor for that range. If the deviation exceeds 2
percent at any point, the best-fit non-linear equation which
represents the data to within 2 percent of each test point shall

be used to determine concentration.


OT

REQUIRED
BACKGR.

ONLY FOR PARTICULATE

ound CORRECTION (OPTroNAL)
READ
— BACKGROUND
i BAG

wv

INTER pATCR|

q—

eater FD)

—

COUNTERS

TO BACKGROUND
SAMPLE BAG

<<
TO EXHAUe
SAMILE Ey (=)

th

EX TUTION — HEATEo tect:

HEATED FID)

TR
<n CeRIrice Ko >
ia Yo

AN VENICLE EAWUET yuan

INLET AAMT LAE
UNE

BYPASS FLOW

READ
BACKGROUND

FIGURE BBL-1B



General Introduction

This document describes recommended test procedures for the
measurement of exhaust emissions from light-duty Diesel vehicles.
Because of overlapping areas in the gasoline-fueled and Diesel
test procedures, this document is structured in Federal Register
format (as published on June 28, 1977, pgs. 32906-33004) in order
to be as clear and unambiguous as possible. It should be specifically
noted that this format incorporates Diesel particulate testing

for the 1981 and later model years. Any sections in the current
Federal Emission Test Procedure (Subpart B) which are affected by
the incorporation of particulate testing are included in this
recommended practice, along with §86.081-2 (Subpart A) which
defines terms associated with particulate testing. A vertical
line in the left margin indicates that a change to the current
procedure has been made on the adjacent line of the text. The
specific changes are enclosed in brackets, [ ], as an aid to the
reader. Sections which pertain entirely to particulate measurement

are identified in the Table of Contents by braces, { }.

The most noteworthy concepts of this test procedure are summarized

in the paragraphs below.

This recommended practice specifies that particulates and regulated
gaseous emissions be measured simultaneously over the same urban

dynamometer driving cycle (§86.110-81 and §86.135-81). The test


-44~

(1) Place drive wheels of vehicle on dynamometer without

starting engine.

(2) Open the vehicle engine compartment cover and position

the cooling fan.

(3) With the sample selector valves in the "standby" posi-
tion connect evacuated sample collection bags to the dilute

exhuast and dilution air sample collection systems.

(4) Start the CVS (if not already on), the sample pumps,
the temperature recorder, the vehicle cooling fan and the heated
hydrocarbon analysis [recorders] (Diesels only). (The heat ex-
changer of the constant volume sampler, if used, Diesel hydro-
carbon analyzer continuous sample [lines] and [filters] (if
applicable) should be preheated to their respective operating

temperatures before the test begins.)

(5) Adjust the sample flow rates to the desired flow rate

and set the gas flow measuring devices to zero.

if (i) For gaseous samples the minimum flow rate is 0.17 CFM

(0.08 1/s).

‘(4i) For particulate samples the minimum flow rate is 0.35

CFM (0.16 1/s). ]


-28-

(d) At least weekly or after any maintenance which could
alter calibration, the following calibrations and checks shall be

performed:

(1) Check the oxides of nitrogen converter efficiency, and

(2) Perform a CVS system verification.

(3) Run a performance check on the dynamometer. This check
may be omitted if the dynamometer has been calibrated within the

preceeding month.

(e) The CVS positive displacement pump or Critical Flow
Venturi shall be calibrated following initial installation, major
maintenance or as necessary when indicated by the CVS system

verification (described in §86.119).

(£) Sample conditioning columns, if used in the CO analyzer
train, should be checked at a frequency consistent with observed

column life or when the indicator of the column packing begins to

show deterioration.


~37-

or three driving cycles of the UDDS, as described in (a)(2) of
this section, each followed by a soak of at least one hour with
engine off, engine compartment cover closed and cooling fan off.
The vehicle may be driven off the dynamometer following each UDDS

for the soak period.

(b) Within five minutes of completion of preconditioning
the vehicle shall be driven off the dynamometer and parked. The
vehicle shall be stored for not less than 12 hours nor for more
than 36 hours (except Diesel vehicles which have no maximum time
limitation) prior to the cold start exhaust test. (Gasoline-
fueled vehicles undergo a one hour diurnal heat: build prior to
the cold start exhaust test. A wait of up to one hour is permitted
between the end of the diurnal heat build and the beginning of

the cold start exhaust test. See §86.130 and Figure B79-5.)

(c) Vehicles to be tested for evaporative emissions shall
be processed in accordance with procedures in §§86.133 through
86.138. Vehicles to be tested for exhaust emissions only shall

be processed according to §§86.133 through 86.137.


~23-

(4i) Sample transport time from sampling point to inlet of

instrument shall be less than 4 seconds.

(iii) The sample line and filter [of the total hydrocarbon
system] shall be heated to [maintain a sample gas temperature of

375° + 10°F (191° + 5.6°C)].

[ (Civ) The sample lines carrying the particulate sample
flow for hydrocarbon analysis shall be heated to maintain a sample
gas temperature of 375° + 10°F (191° + 5.6°C) between a point two

feet (61 cm.) downstream of the particulate filter and the HFID.]

(c) Other analyzers and equipment. Other types of analyzers

and equipment may be used if shown to yield equivalent results

and if approved in advance by the Administrator.


§86.109-81 Exhaust gas sampling system[; gasoline~fueled

vehicles].

{a) (1) General. The exhaust gas sampling system [described
in this paragraph] is designed to measure the true mass [of
gaseous emissions in the exhaust of gasoline-fueled vehicles).

In the CVS concept of measuring mass emissions, two conditions
must be satisfied; the total volume of the mixture of exhaust and
dilution air must be measured, and a continuously proportioned
sample of volume must be collected for analysis. Mass emissions
are determined from the sample concentration and totalized flow

over the test period.

(2) Positive displacement pump. The positive displacement

pump-constant volume sampler (PDP-CVS), Figure [B81-1A], satisfies
the first condition by metering at a constant temperature and
pressure through the pump. The total volume is measured by
counting the revolutions made by the calibrated positive displace-
ment pump. The proportional sample is achieved by sampling at a

constant flow rate.

(3) Critical flow venturi. The operation of the critical
flow venturi-constant volume sample (CFV-CVS), Figure B78-2, is
based upon the principles of fluid dynamics associated with cri-
tical flow. Proportional sampling throughout temperature excur-

sions is maintained by use of a small CFV in the sample line.


-59-

checks be made periodically to verify the low level.

(41) Any manufacturer may make the same assumption without

prior EPA approval.

(441) If PB, is assumed = 0, then no backgound correction is

made and CO, analysis during the second stabilized test is not

2

required since DF no longer has an effect in determining M, .

3

The equation for particulate mass emissions then reduces to:

Vv xP

mix. e
yo ea
Pj “er,

(6) Yep = total volume of sample pulled through the filter,

cubic feet at standard conditions,

. kK, x Yap x Cyar + Pip x 528

Vep Tp x 760

where:

(4) K = dilute exhaust gas meter correction factor deter-

mined in §85.120.

(14),

ap actual dilute exhaust sample volume, cubic feet.

(144) Poar barometric pressure, mm Hg.


-45-

NOTE. - CFV-CVS sample flowrate is fixed by. the venturi

design.

(6) Attach the flexible exhaust tube to the vehicle tail-

pipe(s).

if (7) Carefully install the particulate sample filter into
the filter holder for Diesel tests. The filter must be handled
only with forceps or tongs. Rough or abrasive filter handling

will result in erroneous weight determination. ]

[ (8)] Start the gas flow measuring device, position the

sample selector valves to direct the sample flow into the "transient"
exhaust sample bag and the "transient" dilution air sample bag,

(turn on [each integrator of each] Diesel hydrocarbon analyzer
system, mark [each] recorder chart, [start the particulate sample
pump, and record the dry gas meter reading,] (if applicable),

turn the key on, and start cranking the engine.

[ (9)] Fifteen seconds after the engine starts, place the

transmission in gear.

[ (10)] Twenty seconds after the engine start, begin the

initial vehicle acceleration of the driving schedule.

[ (11)] Operate the vehicle according to the Urban Dynamo-


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of the sample collection phase of the test.

{ (13)] Turn the engine off 2 seconds after the end of the

last deceleration (at 1,369 seconds).

{ (14)] Five seconds after the engine stops running,
simultaneously turn off gas flow measuring device No. 2 (and
[both No. 2] Diesel hydrocarbon [integrators], mark [both] hydro-
carbon recorder [charts], [and turn off the particulate sample
pump,] (if applicable) and position the sample selector valves to
the "standby" position. Record the measured roll or shaft
revolutions, [dry gas meter reading,] and re-set the counter. As
soon as possible, transfer the "stabilized" exhaust and dilution
air samples to the analytical system and process the samples
according to §86.140 obtaining a stabilized reading of the
exhaust sample on all analyzers within 20 minutes of the end of
the sample collection phase of the test. [Carefully remove the
first particulate sample filter from the holder, and place in a

clean covered glass petri dish, if applicable. ]

[ (15)] Immediately after the end of the sample period turn off

the cooling fan and close the engine compartment cover.

{[ (16)] Turn off the CVS or disconnect the exhaust tube from

the tailpipe(s) of the vehicle.


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vehicle shall remain within + 5 inches of water (1.2 kPa) of the
static pressure variations measured during a dynamometer driving
cycle with no connection to the tailpipe(s). (Sampling systems
capabel of maintaining the static pressure to within + 1 inch of
water (0.25 kPa) will be used by the Administrator if a written

request substantiates the need for this closer tolerance.)

(2) The temperature measuring system shall have an accuracy
and precision of + 2°F (1.1°C) and a response time of 0.100
seconds to 62.5 percent of a temperature change (as measured in

hot silicone oil).

(3) The pressure measuring system shall have an accuracy

and precision of + 3 mm Hg (0.4 kPa).

(4) The flow capacity of the CVS shall be Large enough to
virtually eliminate water condensation in the system (300 to 350

cfm, 0.142 to 0.165 m/s, is sufficient for most vehicles).

(5) Sample collection bags for dilution air and exhaust
samples shall be of sufficient size so as not to impede sample

flow.