ASHRAE+62.1-2022+(1) - Page 043
Extracted Content
Table B-1 Minimum Separation Distance
Exhaust Air Class (See Section 5.13) Separation Distance ( L ), ft (m)
Significant contaminant or odor intensity (Class 3) 15 (5)
Noxious or dangerous particles (Class 4) 30 (10)
Table B-2 Exhaust Air Discharge Velocity
Exhaust Direction/Configuration
Exhaust is directed away from the outdoor air intake at an angle that is greater than 45 degrees from the direction of a line drawn from the closest exhaust point to the edge of the intake.
Exhaust is directed toward the intake bounded by lines drawn from the closest exhaust point to the edge of the intake.
Exhaust Air Discharge Velocity ( U ) Modifier
U given a positive value.
U given a negative value.
Exhaust is directed at an angle between the two above cases. U is zero.
Vents from gravity (atmospheric) fuel-fired appliances, plumbing vents, and other nonpowered exhausts, or if the exhaust discharge is covered by a cap or other device that dissipates the exhaust airstream.
Hot-gas exhausts such as combustion products if the exhaust stream is aimed directly upward and unimpeded by devices such as flue caps or louvers.
Table B-3 Minimum Dilution Factors
U is zero.
Add 500 fpm (2.5 m/s) upward velocity to U .
Exhaust Air Class (See Section 5.13) Dilution Factor
Significant contaminant or odor intensity (Class 3) 15
Noxious or dangerous particles (Class 4) 50 [ a]
a. Does not apply to fume hood exhaust. See Section B1.1.
million Btu/h (0.43 L/s per kW) of combustion input (or obtain actual rates from the combustion appliance manufacturer).
U = exhaust air discharge velocity, fpm (m/s). As shown in Figure B-1, U shall be determined using Table B-2.
DF = dilution factor, which is the ratio of outdoor airflow to entrained exhaust airflow in the outdoor air intake. The minimum dilution factor shall be determined as a function of exhaust air class in Table B-3.
For exhaust air comprising more than one class of air, the dilution factor shall be determined by averaging the dilution factors by the volume fraction of each class using Table B-3:
DF = (DF i × Qi )/ Qi (B-3)
where
DF i = dilution factor from Table B-3 for class i air
Qi = volumetric flow rate of class i air in the exhaust airstream
B2.3 Concentration Method. Determine the acceptable concentration for health ( Chealth ) and odor ( Codor ) for each emitted chemical, compound, or mixture.
Design the exhaust and intake systems such that the maximum concentration at the intake ( Cmax ) is less than the acceptable concentrations of all evaluated compounds and mixtures.
Cmax < Chealth (B-4)
Cmax < Codor (B-5)
At a minimum, determination of Cmax shall consider wind speed, wind direction, exhaust exit velocity and momentum, geometry of building and adjacent structures, and architectural screens. Wind tunnel modeling is an acceptable design method.
ANSI/ASHRAE Standard 62.1-2022 41