StacksVerified U.S. regulatory reference

40 CFR Part 63, Table 3

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov
ThermoplasticChemical aVessel capacity (cubic meters)Vapor pressure b (kilopascals)
ASA/AMSAN cstyrene/acrylonitrile mixture≥3.78≥0.47
acrylonitrile≥75.7≥1.62
Polystyrene, continuous processesall chemicals<75.7≥14.2
≥75.7
≥1.9
Nitrilecacrylonitrile≥13.25≥1.8

a Vessel capacity and vapor pressure criteria are specific to the listed chemical or to “all chemicals,” as indicated.

b Maximum true vapor pressure of total organic HAP at storage temperature.

c The applicability criteria in Table 2 of this subpart shall be used for chemicals not specifically listed in this table (i.e., Table 3).

[64 FR 11553, Mar. 9, 1999]