505.11 Hoods and Enclosures. Hoods and enclosures shall

be used where contaminants originate in a concentrated area. The design of the hood or enclosure shall be such that air currents created by the exhaust systems will capture the contaminants and transport them directly to the exhaust duct. The volume of air shall be sufficient to dilute explosive or flammable vapors, fumes, or dusts in accordance with Section 505.9.

	TABLE 505.9 MINIMUM DUCT DESIGN VELOCITIES* [NFPA 91: TABLE A.4.1.5]
NATURE OF CONTAMINANTS	EXAMPLES	FEET PER MINUTE DESIGN VELOCITY (feet per minute)
~~Vapors, gases, smoke~~	~~Vapors, gases, and smoke~~	~~Any~~
~~Fumes~~	~~Welding~~	~~2000~~
~~Fine light dusts~~	~~Cotton lint, wood flour, litho powder~~	~~2500~~
~~Dry dusts and powders~~	~~Fine rubber dust, molding powder dust, jute lint, cotton dust, shavings (light), soap~~ dust, leather shavings	~~3000~~
~~Average industrial dusts~~	~~Grinding dust, buffing lint (dry), wool jute dust (shaker waste), coffee beans, shoe dust,~~ granite dust, silica flour, general material handling, brick cutting, clay dust, foundry (general), limestone dust, packaging and weighing asbestos dust in textile industries	~~3500~~
~~Heavy dusts~~	~~Sawdust (heavy and wet), metal turnings, foundry tumbling barrels and shake-out,~~ sandblast dust, wood blocks, hog waste, brass turning, cast-iron boring dust, lead dust	~~4000~~
~~Heavy or moist dusts~~	~~Lead dust with chips, moist cement dust, asbestos chunks from transite pipe cutting~~ machines, buffing lint (sticky), quick-lime dust	~~4500~~

Systems that are handling combustible particulate solids shall be in accordance with NFPA 654.

88 2019 CALIFORNIA MECHANICAL CODE

EXHAUST SYSTEM

Hoods of steel shall have a base metal thickness not less than 0.027 of an inch (0.686 mm) (No. 22 gauge) for Class 1 and Class 5 metal duct systems; 0.033 of an inch (0.838 mm) (No. 20 gauge) for hoods serving a Class 2 duct system; 0.044 of an inch (1.118 mm) (No. 18 gauge) for hoods serving a Class 3 duct system; and 0.068 of an inch (1.727 mm) (No. 14 gauge) for hoods serving a Class 4 duct system.

of steel shall have a base metal thickness not less than 0.027 of an inch (0.686 mm) (No. 22 gauge) for Class 1 and Class 5 metal duct systems; 0.033 of an inch (0.838 mm) (No. 20 gauge) for hoods serving a Class 2 duct system; 0.044 of an inch (1.118 mm) (No. 18 gauge) for hoods serving a Class 3 duct system; and 0.068 of an inch (1.727 mm) (No. 14 gauge) for hoods serving a Class 4 duct system.

Approved nonmetallic hoods and duct systems shall be permitted to be used for Class 5 corrosive systems where the corrosive mixture is nonflammable. Metal hoods used with Class 5 duct systems shall be protected with an approved corrosion-resistant material. Edges of hoods shall be rounded. The minimum clearance between hoods and combustible construction shall be the clearance required by the duct system. enteral Solutions. [CA –505.12 Pharmacies – Compounding Area of Par-Board of Pharmacy] The pharmacy shall have a designated area for the preparation of sterile products for dispensing which shall be ventilated in a manner not interfering with laminar air flow. Note: For additional pharmacy building standard require- ments, see Chapter 12, California Building Code.

Penetrations of fire walls or floor-ceiling or roof-ceiling assemblies shall be in accordance with the building code. Copper or ferrous pipes or conduits extending from within the separation between a garage and dwelling unit to the central vacuuming unit shall be permitted to be used.

Aluminum ducts shall not be used in systems conveying flammable vapors, fumes, or explosive dusts, nor in Class 2, 3, or 4 systems. Galvanized steel and aluminum ducts shall not be used where the temperature of the material being conveyed exceeds 400°F (204°C).

505.12.1 PSafety Cabinet.harmacies –[CA – Board of Pharmacy]Laminar Flow Biological In all pharmacies preparing parenteral cytotoxic agents, all com- pounding shall be conducted within a certified Class II Type A or Class II Type B vertical laminar airflow hood with bag in – bag out design. The pharmacy must ensure that con- taminated air plenums that are under positive air pressure are leak tight. Note: For additional pharmacy building standard requirements, see Chapter 12, California Building Code.

Metal ducts used in Class 5 systems that are not resistant to the corrosiveness of the product shall be protected with an approved corrosion-resistant material.