Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:20:p13
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 20 (pt 13/29)
Character Range: 250688–253847

service literature, or, if such a governor is not present, the speed at which the maximum power is obtained from the engine, as specified by the manufacturer in his sales and service literature.
3.1.14. "Response time" means the difference in time between the change of the component to be measured at the reference point and a system response of 90 per cent of the final reading (t90) with the sampling probe being defined as the reference point, whereby the change of the measured component is at least 60 per cent full scale (FS) and takes place in less than 0.1 second. The system response time consists of the delay time to the system and of the rise time of the system.
3.1.15. "Rise time" means the difference in time between the 10 per cent and 90 per cent response of the final reading (t90 – t10).
3.1.16. "Span response" means the mean response to a span gas during a 30 s time interval.
3.1.17. "Specific emissions" means the mass emissions expressed in g/kWh.
3.1.18. "Test cycle" means a sequence of test points each with a defined speed and torque to be followed by the engine under steady state (WHSC) or transient operating conditions (WHTC).
3.1.19. "Transformation time" means the difference in time between the change of the component to be measured at the reference point and a system response of 50 per cent of the final reading (t50) with the sampling probe being defined as the reference point. The transformation time is used for the signal alignment of different measurement instruments.
3.1.20. "Transient test cycle" means a test cycle with a sequence of normalized speed and torque values that vary relatively quickly with time (WHTC).
3.1.21. "Zero response" means the mean response to a zero gas during a 30 s time interval.
              Figure 1
              Definitions of system response

3.2. General symbols
Symbol     Unit                            Term
a1         -                               Slope of the regression
a0         -                               y intercept of the regression
A/Fst      -                               Stoichiometric air to fuel ratio

C          ppm/Vol per cent                Concentration

cd         ppm/Vol per cent                Concentration on dry basis

cw         ppm/Vol per cent                Concentration on wet basis

cb         ppm/Vol per cent                Background concentration

Cd         -                               Discharge coefficient of SSV
cgas       ppm/Vol per cent                Concentration on the gaseous components
           particles per cubic centimetre  Average concentration of particles from the diluted exhaust gas corrected to standard conditions (273.2 K and 101.33 kPa) particles per cubic centimetre

cs,i       particles per cubic centimetre  A discrete measurement of particle concentration in the diluted gas exhaust from the particle counter, corrected for coincidence and to standard conditions (273.2 K and 101.33 kPa)
d          m                               Diameter
di                                         Particle electrical mobility diameter (30, 50 or 100 nm)
dV         m                               Throat